Download The impacts of climate change on soil functions

DEPARTMENT for ENVIRONMENT, FOOD and RURAL AFFAIRS
Research and Development
CSG 15
Final Project Report
(Not to be used for LINK projects)
Two hard copies of this form should be returned to:
Research Policy and International Division, Final Reports Unit
DEFRA, Area 301
Cromwell House, Dean Stanley Street, London, SW1P 3JH.
An electronic version should be e-mailed to [email protected]
Project title
Impacts of climate change on soil functions
DEFRA project code
SP0538
Contractor organisation
and location
National Soil Resources Institute
Cranfield Univeristy
Silsoe, Bedfordshire, MK45 4DT
Total DEFRA project costs
Project start date
£ 29,981
01/01/05
Project end date
30/04/05
Executive summary (maximum 2 sides A4)
Background
Soils form through the interaction of a number of influences, including climate, relief/landscape, parent material, above and belowground fauna, flora and human activity, all acting over time. It takes thousands of years for a soil to form and most soils are still
evolving following changes in some of these soil forming factors, particularly climate and vegetation, over the past few millennia.
Changes in any of the soil forming factors, such as climate, will impact directly and indirectly on current soils with important
implications for their development, use and management. This review assumes that UK climate change is a reality and considers its
implications.
Specific changes envisaged under the UKCIP02 scenarios were seen as too detailed to work with given the current state of
understanding of the effect of climate change on soil functioning. More generic trends in climatic variables given by the UKCIP02
scenarios were therefore used, namely:
 Increasing summer temperature
 Increasing winter temperature
 More extreme high temperature
 Less extreme low temperature
 Higher winter rainfall
 Less summer rainfall
 More intense downpours
 Sea level rise and increased coastal flood risk
 More winter storms
A scoping study was carried out to collate results from previously published and current research on the impacts of climate change
and/or other relevant environmental changes on soil functions under different land uses. Findings from the projects reviewed can be
divided into direct impacts on soils (for example, the effect of increased temperatures on decomposition of organic matter) or indirect
impacts (for example the effect that changing litter inputs from plants could have on soil organic matter as a result of changing plant
productivity driven by climatic changes). The impacts are summarised for each of the five core functions of soil identified in the UK
Soil Action Plan (Food and fibre, Soil, air and water interactions, Soil biodiversity, Soils in the landscape and cultural heritage and
Soils in mineral extraction, construction and the built environment). A stakeholder consultation workshop was held and the
CSG 15 (Rev. 6/02)
1
Project
title
Impacts of climate change on soil functions
DEFRA
project code
SP0538
conclusions from it have been included in the report. They are summarised according to the generic climatic changes listed above for
each of the different soil functions. Potential risk management practices and practical measures that land managers might need to
consider to climate-proof soils in the later stages of soil management plans have been identified for agriculture, forestry, built and
disturbed environments. Finally, knowledge and research gaps have been identified and prioritised in terms of policy and stakeholder
needs, and ways forward have been proposed.
Direct impacts of climate change on soil functions
Assuming constant inputs of carbon to soils from vegetation, soil-climate models predict that expected changes in temperature,
precipitation and evaporation will cause significant increases in organic matter turnover and increased losses of CO 2 in mineral and
organic soils across the UK. This will result in a positive feedback between CO 2 emissions from soils and further temperature
increase. These broad predictions have been partially corroborated by the changes in national soil carbon stocks measured in the
National Soil Inventory. However further work is required to separate effects of climate change and land use change.
Losses of soil carbon will also affect other soil functions. The greatest losses, relative to existing soil carbon content, are expected in
south east England, where rates of temperature increase are greatest. This could lead to poorer soil structure, stability, topsoil water
holding capacity, nutrient availability and erosion. However, these effects could be offset by enhanced nutrient release resulting in
increased plant productivity and hence litter inputs. Relatively little comparative research has been done on organic soils, although
scoping work suggested drying out of Welsh bogs might occur in the absence of deliberate management intervention, resulting in
increased GHG fluxes and thus a positive climate feedback. In Scotland, areas experiencing increased rainfall could expect increased
peat formation and methane release, whilst areas experiencing decreased rainfall amounts could undergo peat, and hence CO2 loss.
Changes in soil moisture content have also been predicted – including increased moisture deficit for arable crops (especially on
shallow soils) and for forest soils in south east Scotland. This could have direct impacts on soil invertebrates affecting foraging
patterns, reproduction and survivability, with potential indirect impacts on other parts of the food web which are dependant upon
them. Similarly changes in the survival of natural plant pathogens could alter susceptibility of ecosystems to non-native invaders.
Increased droughts will increase the likelihood of shrink-swell in clay soils, and disturbance to building foundations and need for
underpinning/repair. Increased soil temperature may also exacerbate chemical attack to foundations. There is a potential risk to
engineered structures based on clay caps (e.g. in contaminated landfills), with likelihood of increased leachate generation and release
of landfill gases.
Variable and largely unknown overall effects on pesticide fate and losses could be expected, due to the complex nature of interactions
between pesticides and the environment under a changing climate. For example, increased applications of pesticides could result from
an increased incidence of pests and diseases, although higher temperatures could cause more rapid degradation. Changes in rainfall
patterns could lead to increased losses via bypass flow and increased degradation in winter, but increased persistence could occur as a
result of drier conditions during summer and increased transfer to groundwater could result from more intense and frequent storm
events. Careful planning of the amounts and timing of application of fertilisers and pesticides would help to minimise these effects.
Increased winter rainfall, and particularly an increased frequency and intensity of extreme rainfall events could increase problems
with land stability and landslips. Generally small effects on erosion are expected in Scotland, although increased erosion might occur
during winter. Increased rainfall could increase atmospheric N deposition to soils. Increased winter waterlogging due to higher
precipitation may promote soil disturbances as a result of tree windthrow. If good practice guidelines are not adhered to, then an
indirect effect of climate change would be soil compaction and deterioration in soil structure. Leaching of nitrogen and DOC may also
be enhanced by increased winter rainfall which will consequently affect water quality.
Flooding and subsidence could affect archaeological sites and changes in wetland and waterlogged habitats could result in damage to
artefacts, although drier summer conditions would improve reconnaissance activities for archaeology. Increased flooding and more
intense rainfall events will enhance soil erosion. An additional risk on brownfield land is the erosion of contaminated soil materials,
potentially leading to the pollution of surface waters. Drainage systems may therefore need to be re-designed to accommodate more
extreme and frequent floods. Soil and vegetation changes might occur, leading to degradation of sensitive montane habitats,
particularly in Wales and Scotland. There will be impacts on the decomposer community.
Indirect impacts of climate change on soils
The integrated impact of climate change is expected to generally increase crop yields (with winter wheat, sunflower and sugar beet
having been investigated in detail), as a result of the combined effects of CO 2 fertilisation, radiation use efficiency and longer growing
seasons. Increased sunflower yields might enable this crop to become competitive with oilseed rape in East Anglia. Smaller increases
in yield or possible decreases are expected for light soils in southern England, and parts of south east Scotland suffering increased
water stress. Decreased yields could also be expected for potatoes in Cornwall, oilseed rape in south and southeast England and high
quality horticultural crops in Scotland. Increased CO2 concentrations should lead to greater plant productivity. Increased temperatures
might, however result in decreased yields (and hence litter inputs), although this would generally be offset by the CO 2 fertilisation
effect. Increases in grass yields are also generally expected. Both climatic warming and rising CO 2 levels in the atmosphere will
enhance tree growth in the short term. However, no UK-based research has corroborated these contentions in the longer term or for
mature canopies, with current predictions based on a combination of impact studies on young trees and modelling. Reduced N inputs
to crops might be needed with the exception of some areas in Scotland where small increases in N inputs could be required. Reduced
N inputs could result in lower N leaching, although this will also depend on how changes in rainfall and temperature affect the N
cycle and water movement.
CSG 15 (Rev. 6/02)
2
Project
title
Impacts of climate change on soil functions
DEFRA
project code
SP0538
In summary, increased productivity would generally lead to greater inputs of carbon to soil, thus increasing SOM. However, this
depends on:
 how elevated CO2 and temperature and changes in rainfall affects the allocation of C above and below ground
 harvest index of future crop varieties and management in forestry (e.g. type of harvesting)
 how changes in temperature and moisture affect SOM turnover.
Generally, fewer work days would be available for arable cultivation in autumn, spring and winter, which could have negative
impacts on soil structure, increased erosion, N2O emissions, and P, N, S and pesticide losses although again this would depend on
interactions with climatic changes. Regions in the west of the UK, however, might experience an increase in work days. Greater
irrigation of root crops is likely to be necessary for sugar beet and potatoes in East Anglia.
Potential impacts of land use change
Possible land use changes could include reduced areas of arable land in East Anglia, the conversion of upland grass to arable in the
Northwest, increased afforestation in Scotland and general increases in areas under barley and set-aside. More specialisation in cereal
and root crops is likely with more spring crops being sown in Scotland, with the crop ranges spreading northwards. Land use change
has considerable potential to alter soil properties. For example, changes in vegetation cover could alter runoff and nutrient losses as
well as SOM content. Similarly, changes in the soil biota may have knock-on effects on soil structural stability, soil biodiversity,
plant-soil interactions and nutrient cycling. However, socio-economic trends are likely to have a dominant role in determining land
use patterns, thus making general predictions problematic. Flooding and sea-level rise are likely to lead to a loss of arable land in lowlying and coastal areas of England and Wales, whilst increases in arable land and woodland establishment on the floodplain elsewhere
could increase the risk of damage to archaeological remains.
Recommendations
Research
1. More research specifically aimed at soil functions under climate change is recommended. Climate impacts research not directly
focused on soils should incorporate, wherever possible, a consideration of possible soil impacts. Existing research using the
UKCIP98 scenarios should be updated using UKCIP02 – or at the very least, an assessment of possible changes to research
conclusions should be undertaken.
2. Further investigation of the interactions between climate change and pollutant deposition and exposure, particularly critical loads
and their exceedance for agricultural land and woodland in relation to issues of acidification/recovery and eutrophication.
3. Future research into soil functions under climate change should attempt to deal with uncertainties in climate predictions and soil
process model formulation and parameterisation of soil processes. Model development for organic and woodland soils needs to
be promoted, including the collection of data required for parameterisation and verification.
4. Studies integrating the impact of land use changes and socio-economic factors should be encouraged since these may be as
important as the impacts of climate change on soil functions.
5. Further targeted research is recommended to investigate the effects of CO 2 combined with changes in the temperature regime on
soil function, directly or indirectly, and interactions with changes in temperature and rainfall.
6. More research is warranted on the ability of soils to hold and buffer pollutants in the face of climate change, particularly on
“brownfield” soils as well as in the urban, built environment.
7. Improved estimates of non-CO2 GHG balance (primarily N2O and CH4) of forest soils, including predictions of the impacts of
climate change and the effects of forest management; extension to broadleaf woodland and deforestation activities is important.
Monitoring
8. Long-term site-specific monitoring studies (for example long-term experiments, ECN, Level I, Level II Long term monitoring of
forest ecosystems) as well as information from National Inventories and soil surveys should be used, where relevant, for
benchmarking and guiding new monitoring work to assess climate impacts on soil functions.
9. Inventories of carbon stocks and stock changes should be enhanced with a focus on particularly vulnerable soils, including an
assessment of the effects of forest management.
Education
10. There should be an extension of education initiatives to increase awareness of the impact of climate change on soils as it affects,
for instance, water resources, pollution and erosion.
Integration
11. Better integration between research projects both within and between research funding bodies is recommended to achieve
considerable added value for relatively little effort
12. Research into developing and applying integrated, holistic modelling assessment tools considering soil, climate, vegetation and
water interactions should be supported to allow a scientifically robust assessment of climate impacts on soil functions.
13. Research investigating and integrating the use of currently available soil process models (for example, pesticide fate, water
relations, nutrient cycling and GHG fluxes) for climate impacts studies should be encouraged.
14. The collation of information on the likely effects of climate change on soil chemical and physical properties and how
archaeological remains may be affected.
CSG 15 (Rev. 6/02)
3
Project
title
Impacts of climate change on soil functions
DEFRA
project code
SP0538
15. The collation and integration of existing datasets and modelling tools relevant to the principal soil processes. This is an essential
step in developing Decision Support Systems for climate change risk management, with the objective of implementing adaptation
measures to maintain soil sustainability.
Next stage
16. It is suggested that a Stakeholder meeting should be held to allow discussion of the review and to identify priorities for the
development of tools to mitigate and adapt to the impact of climate change on soils.
CSG 15 (Rev. 6/02)
4
Project
title
Impacts of climate change on soil functions
DEFRA
project code
SP0538
Scientific report (maximum 20 sides A4)
1 INTRODUCTION
Soils form through the interaction of a number of influences, including climate, relief/landscape, parent material, organisms including
fauna, flora and man, all acting over time. It takes thousands of years for a soil to form and most soils are still evolving following
changes in some of these soil forming factors, particularly climate and vegetation, over the past few millennia. Changes in any of the
soil forming factors, such as climate, will impact directly and indirectly on current soils with important implications for their
development and use.
Unravelling the likely extent and impact of climate change on soils is a complex process and progress has been slow. It is made all the
more complicated by the fact that not only can soils be strongly affected by climate change directly, for example effect of temperature
on soil organic matter decomposition, and indirectly, for example changes in soil moisture via changes in plant related
evapotranspiration, but soils themselves can act as a source of greenhouse gases and thus contribute to the gases responsible for
climate change. In addition changes in the functions and uses soils may be driven more by socio-economic factors than
environmental ones. The lack of specificity of the global circulation models (GCMs) at present, combined with the complexity of the
interaction of the various soil forming processes and the fact that there is still a limited knowledge of many of them, particularly
biological ones, makes it difficult to quantify the changes that will ensue. On the basis of current knowledge it is only possible to
describe the likely impacts of climate change on soils in a qualitative or semi-quantitative way and highlight the key changes, their
direction and, where there is adequate climate change information, their implications for management.
2
OBJECTIVES
The instructions set for the research reported here were to:
1.
Collate results from previous research on the impacts of climate change (using UKCIP scenarios) and or other relevant
environmental changes on soils and soil functions, including taking into account the biological component of the soil.
2.
Make use of wide stakeholder consultation.
3.
Scope the impacts and risks of climate change.
4.
Identify potential risk management practices (including non-agricultural land-management practices).
5.
Identify practical measures that land managers might consider to climate-proof soils in the later stages of soil management
plans for agriculture, but will also examine other implications of climate change for management of the various land types
(agriculture, forestry, built environments, disturbed environments).
6.
Identify suitable soil reference sites, including those where different vulnerabilities 1 are evident now.
7.
Identify knowledge and/or research gaps and prioritise these in terms of policy and stakeholder needs.
8.
Collate and identify the ways forward and those preferred by stakeholders.
3
SCOPE THE IMPACTS AND RISKS OF CLIMATE CHANGE
Estimates of global climate change are continually being revised as models are being improved and new data collected. The current
main sources of information available on the likely extent of climate change are the Third Assessment Reports of the
Intergovernmental Panel on Climate Change (IPCC 2001) and the climate change scenarios for the UK (UKCIP02) (Hulme et al.
2002).
The Intergovernmental Panel on Climate Change (IPCC) estimates that the globally averaged surface temperature will increase by
between 1.4 and 5.8C over the period 1990 to 2100 and that nearly all land areas will warm by more than this global average,
1 1
In relation to hazards and disasters, vulnerability is a concept that links the relationship that people have with their
environment to social forces and institutions and the cultural values that sustain and contest them. “The concept of
vulnerability expresses the multidimensionality of disasters by focusing attention on the totality of relationships in a given
social situation which constitute a condition that, in combination with environmental forces, produces a disaster”
(Bankoff, Greg, George Frerks and Dorothea Hilhorst. 2004. Mapping Vulnerability. Sterling: Earthscan).
Risk is the potential harm that may arise from some present process or from some future event. It is often mapped to the
probability of some event which is seen as undesirable. Usually the probability of that event and some assessment of its
expected harm must be combined into a believable scenario (an outcome) which combines the set of risk, regret and
reward probabilities into an expected value for that outcome. There are many informal methods which are used to assess
(or to "measure" although it is not usually possible to directly measure) risk, and (for some applications) formal methods
such as value at risk.
CSG 15 (Rev. 6/02)
5
particularly in northern high latitudes in the cold season (Table 1). Increased summer continental drying and associated risk of
drought is likely over most mid-latitude interiors, the main areas for which the models are consistent with one another.
Table 1 Projected changes in extreme weather during 21st centurya
Changes in weather phenomenon
Confidence in projected changes
Higher maximum temperatures and more hot days over nearly all
land areas
Very likely
Higher minimum temperatures, fewer cold days and frost days
over nearly all land areas
Very likely
Reduced diurnal temperature over most land areas
Very likely
Increase of heat indexb over land areas
Very likely, over most areas
More intense precipitation events
Very likely, over many areas
Increased summer continental drying and associated risk of
drought
Likely over most mid-latitude continental interiors (Lack of
consistent projections in other areas)
Increase in tropical cyclone wind intensities
Likely, over some areas
Increase in tropical mean and peak precipitation intensities
Likely, over some areas
a
Adapted from IPCC, 2001: Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment
Report of the Intergovernmental Panel on Climate Change. (Houghton et al. (Eds)). Cambridge University Press. Table 4, page 72.
b
Heat Index – A combination of temperature and humidity that measures effects on human comfort
The description of future UK climate by UKCIP is based on four different emissions scenarios published by IPCC (Table 2; Box 1).
It is impossible to assign objective likelihoods to these emissions scenarios, since they depend on choices made by society (Hulme et
al. 2002). For the purposes of this scoping study it was decided to assess broad statements of change, in line with other similar
exercises by UKCIP, namely:









Increasing summer temperatures
Increasing winter temperatures
More extreme high temperatures
Less extreme low temperatures
Higher winter rainfall (Figure 1)
Less summer rainfall
More intense downpours
Sea level rise and increased coastal flood risk
Possibly more winter storms.
Table 2 UKCIP02 emissions scenarios
SRES Emission
scenarios
UKCIP02 Climate Change Scenario
Global temperature
increase (oC)
Atmospheric CO2
concentration (ppm)
A1F1
High emissions
3.9
810
A2
Medium-high emissions
3.3
715
B2
Medium-low emissions
2.3
562
B1
Low emissions
2.0
525
CSG 15 (1/00)
6
Box 1 Key results of UKCIP report (Hulme et al. 2002)








2
3
UK climate will2 become warmer. By the 2080s, annual temperature averaged across the UK may3 rise by
between 2ºC for the Low Emissions scenario and by 3.5ºC for the High Emissions scenario. There will be
greater warming in the south and east than in the north and west, and there may be greater warming in summer
and autumn than in winter and spring. By the 2080s for the High Emissions scenario, parts of the southeast may
be up to 5ºC warmer in summer. The temperature of UK coastal waters will also increase, although not as rapidly
as over land.
High summer temperatures will become more frequent and very cold winters will become increasingly rare. A
very hot August, such as experienced in 1995 when temperatures over central England averaged 3.4ºC above
normal, may occur one year in five by the 2050s for the Medium-High Emissions scenario, and as often as
three years in five by the 2080s. Even for the Low Emissions scenario, by the 2080s about two summers in
three may be as hot as, or hotter than, the exceptionally warm summer of 1995.
Winters will become wetter and summers may become drier everywhere. The relative changes will be largest for
the High Emissions scenario and in the south and east of the UK, where summer precipitation may decrease by
50 per cent or more by the 2080s and winter precipitation may increase by up to 30 per cent. Summer soil
moisture by the 2080s may be reduced by 40 per cent or more over large parts of England for the High
Emissions scenario.
Snowfall amounts will decrease throughout the UK. The reductions in average snowfall over Scotland might be
between 60 and 90 per cent (depending on the region) by the 2080s for the High Emissions scenario.
Heavy winter precipitation (rain and snow) will become more frequent. By the 2080s, winter daily precipitation
intensities that are experienced once every two years on average may become between 5 per cent (Low
Emissions) and 20 per cent (High Emissions) heavier.
Relative sea level will continue to rise around most of the UK’s shoreline. The rate of increase will depend on the
natural vertical land movements in each region and on the scenario. By the 2080s, sea level may be between 2
cm below (Low Emissions) and 58 cm (High Emissions) above the current level in western Scotland, but
between 26 and 86 cm above the current level in southeast England.
Extreme sea levels will be experienced more frequently. For some east coast locations, extreme sea levels could
occur between 10 and 20 times more frequently by the 2080s for the Medium-High Emissions scenario than
they do now.
The Gulf Stream may weaken in future and the changes in climate described in this report reflect this. It is unlikely
that this weakening would lead to a cooling of UK climate within the next 100 years. We do not understand
enough about the factors that control this ocean circulation, however, to be completely confident about this
prediction, especially in the longer term.
The word ‘will’ is used where UKCIP has High Confidence about an outcome.
The word ‘may’ is used where UKCIP has less than High Confidence about an outcome.
CSG 15 (1/00)
7
Figure 1 Emissions scenarios and their effects on soil moisture
3.1
Timescale for change
The diverse range of physical, chemical and biological processes that affect soil formation and modify soil properties will respond to
climate change according to varying timescales (Table 3). Parameters such as bulk density, porosity, infiltration rate, permeability,
nitrate content and composition of soil air can change on a daily basis, depending on the weather. At the other end of the time scale,
weathering of minerals as part of soil formation and changes in soil texture are more likely to be on millennial time scales. The effect
of climate change will be to modify the rates of these processes and lead to changes in soil properties with a range of implications for
soil formation, soil genesis, and the way in which soils can be used. Its potential impact on some of the major processes and properties
is described below.
CSG 15 (1/00)
8
Table 3 Time scale for changes in soils with change in climate
Time scale
categories
Soil parameter
Properties and characteristics
Regimes
<10-1 yr
Temperature; moisture content; bulk density;
total porosity; infiltration rate; permeability;
composition of soil air; nitrate content
Compaction; drainage; workability
Aeration; heat regime
10-1-100 yr
Total water capacity; field capacity;
hydraulic conductivity; pH; nutrient status;
composition of soil solution
Microbiota
Microbial activity;
human controlled plant
nutrient regime; erosion
100-101 yr
Wilting percentage; soil acidity; cation
exchange capacity; exchangeable cations
Type of soil structure; annual roots
biota; meso-fauna; litter, fluvic, gleyic,
stagnic properties; slickensides
Moisture; natural
fertility; salinityalkalinity;
desertification;
permafrost
101-102 yr
Specific surface; clay mineral association;
organic matter content
Tree roots soil biota; salic, calcareous,
sodic, vertic properties
102-103 yr
Primary mineral composition; chemical
composition of mineral part
Tree roots; colour (yellowish/reddish);
iron concretions; soil depth; cracking;
soft powdered lime; indurated sub-soil
>103 yr
Texture; particle-size distribution; particle
density
Parent material; depth; abrupt textural
change
Reproduced with minor modifications from Varallyay, GY, (1990) Influence of climatic change on soil moisture regime, texture, structure and
erosion. In : Scharpenseel, HW, Schomaker, M and Ayoub, A. (eds) Soils on a Warmer Earth. page 46. Elsevier, Amsterdam.
3.2
Climate change impacts on soil water and soil temperature
Soil water
The main effects of climate change on soils will be through changes to soil moisture regimes. Soil moisture is a key driver to most soil
processes and is instrumental in the use that can be made of soils. As climate changes, soil moisture levels will be influenced by direct
climatic effects (precipitation, temperature effects on evaporation), climate induced changes in vegetation, different plant growth rates
and different cycles, different rates of soil water extraction and the effect of enhanced CO 2 levels on plant transpiration. Changes in
soil water fluxes may also feed back to the climate itself and even contribute to drought conditions by decreasing available moisture,
altering circulation patterns and increasing air temperatures.
Soil water can be influenced in a number of ways by climate change. Changes in precipitation will rapidly affect soil water since the
time-scale for response to rainfall in the soil is usually within a few hours. Increasing temperatures will also lead to greater
evapotranspiration and hence loss of water from the soil. Much will depend on land use also, which itself will change, together with
its water needs.
Several soil forming processes, including organic matter turnover, structure formation, weathering, podzolisation, clay translocation
and gleying, are strongly affected by soil moisture contents. The type of soil structure that develops under a particular climatic regime
is particularly important because it affects the processes of run off, infiltration, percolation and drainage, processes that are vital in the
distribution of water across the landscape.
Those areas predicted to have warmer temperatures and less rainfall will have less soil moisture with potentially large implications for
the crops that can be grown and the natural and semi-natural ecosystems that can continue to exist. The temporal nature of changes in
climatic variables is particularly important, for example less soil moisture in summer, more soil moisture in winter.
It is, however, difficult to predict, given the many different interacting influences on soil moisture levels, what the effect of climate
change will be on soil water at regional or local level. This difficulty is accentuated because soil water contents are highly variable in
space, with different impacts identified in different parts of the UK and general climate change models are some way from predicting
the climate changes likely at regional and particularly local level.
Soil temperature
There is a close relationship between air temperature and soil temperature and a general increase in air temperature will inevitably
lead to an increase in soil temperature. The temperature regime of the soil is governed by gains and losses of radiation at the surface,
the process of evaporation, heat conduction through the soil profile and convective transfer via the movement of gas and water. As
with soil moisture, soil temperature is a prime mover in most soil processes. Warmer soil temperatures everywhere will accelerate soil
processes, leading to more rapid decomposition of organic matter, increased microbiological activity, quicker release of nutrients,
CSG 15 (1/00)
9
increased rates of nitrification and generally increased chemical weathering of minerals. However, soil temperatures will also be
affected by the type of vegetation occurring at its surface, which may change itself as a result of climate change, or adaptation
management.
3.3
Changes in soil forming processes and properties
Soil organic matter
Soil organic matter is arguably the most important soil component, influencing as it does soil structure, water holding capacity, soil
stability, nutrient storage and turnover and oxygen-holding capacity, properties that are fundamental in maintaining and improving
soil quality. A decline in organic matter content increases the susceptibility to soil erosion. Organic matter is particularly important as
the prime habitat for immense numbers and variety of soil fauna and microflora, which play a critical role in the health and
productivity of soils. It is highly susceptible to changes in land use and management and to changes in soil temperature and moisture.
In the last decades changes in land use and management have already led to a significant decline in organic matter levels in many soils
(REF).
Soil organic matter is one of the major pools of carbon in the biosphere and unlike most other soil properties is important both as a
driver of climate change and as a response variable to climate change, capable of acting both as a source and sink of carbon during
climate change. How climate change will impact on soil organic matter is a matter of considerable debate. On the one hand it is
recognised that global warming and increasing CO2 levels in the atmosphere can favour increased plant growth, which in turn could
provide more organic matter for the soil. On the other hand a rise in air temperature and that of the soil would be consistent with an
increase in decomposition and loss of soil organic matter. There is thus significant interest in the fate of such carbon, particularly the
extent to which soils and land use can be used to regulate the sequestration of carbon from the atmosphere or the loss of soil organic
carbon to the atmosphere. The balance of opinion currently is that in the absence of mitigating action, losses through organic matter
decomposition are likely to exceed levels gained from increased plant growth, thus adding to atmospheric CO 2 levels and the
greenhouse gas effect and to lower levels of soil organic matter (REF).
A group of soils that are particularly vulnerable to climate change are the peat soils. These are soils that are dominantly composed of
organic matter throughout their whole depth. Already they have been under threat because of drainage for use in crop production.
Further drying out of the soils in a warmer drier climate with concomitant oxidation could lead to losses of this important, highly
productive soil type (REF) so incurring large losses of carbon and therefore contributing to a potential positive climate feedback.
Soil structure
The structure of the soil, that is the way in which the soil particles combine together, is an important property of soils, affecting the
movement of gases, water, nutrients, soil fauna and the emergence of crops. The nature and quality of the structure of particular soils
is strongly influenced by the amount and quality of organic matter present and also by the inorganic constituents of the soil matrix,
cultivation methods and by natural physical processes such as shrink-swell and freeze-thaw. A decline in soil organic matter levels as
could occur under climate change might lead to a decrease in soil aggregate stability, an increase in susceptibility to compaction,
lower infiltration rates, increased run-off and hence, an increased susceptibility to erosion (REF).
The structure of the soil is also important for water quality, seepage and building foundations. Soils with high clay contents,
particularly those with smectitic mineralogy, have the potential to shrink when dry, resulting in formation of large cracks and fissures.
When the soils re-wet again the cracks close. Drier climatic conditions would be expected to increase the frequency and size of crack
formation. The importance of soil structure in determining pathways for the movement of water, pollutants and contaminants through
the soil is now well recognised and future management of soil water, movement of nutrients within the soil and the landscape, and the
movement of contaminants once in the soil are important aspects to be considered in a climate change environment. In some areas
there could be an increase in flash flooding as a result of increased cracking and change in structure.
Areas that are likely to experience increased droughtiness may also find that buildings, roads etc, built to particular specifications
relating to current conditions, have foundations which become unstable as soils dry out more. For example, the increase in subsidence
to buildings in south-east England alone in the decade to 1997, the warmest recorded, cost the insurance industry about 4500 billion
Euros (REF).
Clay soils with a high shrink-swell potential are important agricultural soils but are renowned as some of the problem soils of the
country due to difficulty in managing them for cultivation. Changes in climate, particularly increased drying of the soil, will lead to
increased difficulties in their management.
Soil fauna and soil flora
Soil fauna and flora are essential components of all soils. Particularly vital is their role in the retention, breakdown and incorporation
of plant remains, nutrient cycling and their influence on soil structure and porosity. There are thousands of species in a metre square
of most soils but despite these numbers and their importance, little is known about the roles of the species. Global warming may not
have a direct effect on the ecological composition because soil fauna and flora have a relatively broad temperature optimum.
However, changes in ecosystems and migration of vegetation zones are likely in some areas as a result of increased temperature and
CSG 15 (1/00)
10
changes in rainfall. Some soil flora and fauna may be seriously affected by such changes because their migration rates are likely to be
too small.
A further significant impact of climate change on soil fauna and flora is through enhanced CO 2 levels in the atmosphere leading to
enhanced plant growth and in turn increased allocation of carbon below ground. The microbial population and its activity under this
regime would lead to higher rates of nitrogen fixation, nitrogen immobilisation and denitrification, increased mycorrhizal
associations, increased soil aggregation and increased weathering of minerals. However, as noted above, much will depend on what
balance between increased plant growth on the one hand and increased decomposition of soil organic matter on the other will emerge
under a changing climate.
Acidification and nutrient status
While temperature increases are forecast for most parts of the world, there is less certainty about precipitation changes. Significant
increases in rainfall will lead to increases in leaching, loss of nutrients and increasing acidification, depending on the buffering pools
existing in soils. The direction of change towards increased leaching or increased evaporation will depend on the extent to which
rainfall and temperature change, and consequent changes to land use and its management. In either case the situation could lead to
important changes in soils.
Soil erosion
Soil erosion is the movement and transport of soil by various agents, particularly water, wind and mass movement; hence climate is a
key factor. It has been recognised as a major problem since the 1930’s and although there has been some 70 years research into the
causes and processes, it is still increasing and of growing concern.
The increase in soil erosion is strongly linked with the clearance of natural vegetation, to enable land to be used for arable agriculture
and the use of farming practices unsuited to the land on which they are practised. This, combined with climatic variation and a
predicted increase in extreme weather events, has created ideal conditions for soil erosion. The main climatic factors influencing soil
erosion are rainfall (amount, frequency, duration and intensity), and wind (direction, strength and frequency of high intensity winds),
coupled with drying out of the soil. Land use, soil type and topography are the other key factors.
Soil erosion by water is more widespread and its impact greater than that by wind. Climate change is likely to affect soil erosion by
water through its effect on rainfall intensity, soil erodability, vegetative cover and patterns of land use. General circulation models
indicate a marked change in soil moisture regime for some areas and therefore changes also in soil erodability, vegetation and land
use. For many areas, they also predict seasonally more intense drying out coupled with increased amounts and intensity of
precipitation at other times, conditions that could lead to a large increase in rates of erosion by water.
Soil erosion also occurs by wind transport of soil particles by suspension, surface creep or saltation over distances ranging from a few
centimetres to hundreds of kilometres. Wind erosion is particularly a problem on sandy and organic soils where they are subject to
intermittent low moisture contents, and periodic winds. Those areas where climate change is predicted to lead to more droughty soils
under increasing temperatures will become increasingly vulnerable. Although general circulation models have in the past been unable
to predict changes in wind speed and frequency with any certainty, the latest models are predicting increased summer continental
drying and risk of drought in mid-latitude areas and an increase in tropical cyclone peak intensities in some areas, both sets of
conditions favouring an increase in soil erosion by wind. However, it is important to note that erosion is site specific and different
permutation of conditions can increase or decrease it.
4
COLLATE RESULTS FROM PREVIOUS RESEARCH ON THE
IMPACTS OF CLIMATE CHANGE AND/OR OTHER RELEVANT
ENVIRONMENTAL CHANGES ON SOILS AND SOIL FUNCTIONS,
INCLUDING TAKING INTO ACCOUNT THE BIOLOGICAL COMPONENT
OF THE SOIL.
4.1
Introduction
It is anticipated that as the UK climate progressively changes, there will be an increasingly significant impact on soils and soil
functions, perhaps influencing the management and hydrological functioning of soils in many ecosystems. Most existing knowledge is
based upon agricultural systems, although these are not necessarily the most vulnerable. There is a distinct lack of information in
relation to the vulnerability of non-agricultural soils (including those in the urban environment). The UKCIP (UK-wide) approach to
assessing climate change impacts is not to separate the current climate and its inherent variability from the additional or altered risks
attributed to climate change.
Major UK research funders’ internet databases were searched for projects for soils and/or climate change, which were then filtered
according to information available on different projects. In total, over one hundred projects from eight funding bodies were
investigated and are further reviewed here (Figures 2 to 5). English Nature, HGCA and the Soil Association internet sites were also
CSG 15 (1/00)
11
searched, although none of these revealed projects relevant to soil functions and climate change. The major focus of this review is on
climate change impacts studies (the influence of changes in climate on soil processes), although related studies have also been
included where directly or indirectly relevant, such as process model development or impacts on crops.
Figure 2 Soil parameters and processes considered by reviewed projects (projects with no soil information are not included)
30
25
20
15
10
5
Multiple
Spatial variability
Water
Structure/aggregation/
strength
SOM/C
S cycling
Microbiology
N cycling
P cycling
Pesticides
Erosion
CH4 flux
CO2 flux
N2O/NO flux
GHG flux - general
0
Figure 3 Sectors considered by reviewed projects (projects with no sector information are not included)
Gardens
Infrastructure/engineeri
ng/building
Business/Industry
Multiple
Mining/waste disposal
Natural systems
Water/flood defence
Biodiversity
Coastal
Grasslands
Agriculture
Urban/domestic
Forestry
70
60
50
40
30
20
10
0
Figure 4 Geographic context of reviewed projects (projects with no geographic information are not included)
30
25
20
15
10
5
G
lo
ba
l
La
bo
ra
to
ry
el
d/
sit
e
ot
/fi
Pl
ur
op
ea
n
Na
tio
na
l/E
as
e
Re
gi
on
al
/c
M
ul
tip
st
ud
y
le
0
Figure 5 Climate change scenarios considered by reviewed projects (projects with no scenario information are not included)
CSG 15 (1/00)
12
M
Ha
dR
Sp
M
3
ec
ific
ev
en
t
Hi
st
or
ic
RC
SR
ES
UK
CI
P
02
Ha
dC
M
3
UK
UK
CI
CI
P
P9
(n
ot
8
sp
ec
ifie
d)
Ha
dC
M
2
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
A second review centred on published and unpublished information on the effects of climate change on forest soil functions in the
UK. The search for published information in forms of peer-reviewed articles, conference proceedings and presentations was carried
out by different web based search engines such as Google, Scirus Web of Knowledge, etc. In total, there were 35 published papers
reporting on a research specifically designed to investigate the climate change effect on forest soils (Appendix Table 6). There were
45 more published papers where indirect related effects of climate change on soils were mentioned. Relevant personnel in universities
and research organisations and institutes were contacted for information on their published and unpublished research on climate
change and forest soils (Appendix Table 7). In addition, a web based search on past and current projects sponsored by Defra and other
UK funding bodies associated with the climate change on forest soils was carried out (Appendix Table 8). Specific findings of the
projects are reviewed in the Appendix.
4.2 Defra-funded projects
A broad range of Defra projects has been commissioned specifically regarding climate change impacts, although few have been
directly focussed on soil functions. Topics covered include climate change implications for: habitats and space, farm level responses,
adaptation and costs and knowledge transfer, drought stress and UK crops, regional case studies including extreme climate events,
agricultural land use patterns, agricultural thresholds, grassland sustainability, the use of past events for impacts assessment,
development of a soil properties database for impacts studies, nutrient cycling and pollution, monitoring, modelling, organic matter
changes, pesticide fate, water demands, impacts on gardens, and climate change indicators.
Defra have also funded a range of projects related to GHG emissions and the GHG emissions inventory, covering land use change
impacts, development of soil carbon models and supporting databases, N2O flux models and emission factors, NO emissions and CH4
emissions and a review of the GHG emissions programme was recently completed.
Other relevant research projects include support for long-term monitoring networks (ECN), support for atmospheric nitrogen
enrichment studies (GANE), development of phosphorus and pesticide fate models, and SOM and soil carbon research (modelling, C
sequestration, critical levels and SOM indicators, trends and soil health).
4.3 NERC-funded projects
In general, relevant NERC research covers the climate impacts specifically (global soil C stocks, plant biodiversity, N deposition and
climate-snow-hydrology interactions in tundra systems), carbon cycle (climate change impacts on soils globally, forest soil C stores,
decomposition processes and soil fauna), and model development (support for a Global Environmental Model and uncertainty
analysis).
A number of research projects have been investigating issues related to soil functions and climate change, including the impact of soil
carbon decomposition on future global climate; modelling climate and land use influences on spatial patterns of UK plant biodiversity
(using soil maps); application of uncertainty estimation techniques in environmental modelling to land use and climate change studies;
whether N deposition is affecting the Welsh uplands and impacts of climate change on recovery; and climate, snow and hydrology
interactions in tundra ecosystems. Studentships have been awarded to study the vulnerability of carbon stores in UK forest soils; the
role of land use, temperature and water in carbon release from soils; the effects of climate change on carbon storage in high-latitude
peatlands; controls of DOC concentrations in soil and surface waters; monitoring and modelling of active gully systems and sediment
export in upland Britain under climate change; impacts of soil erosion in the uplands on the terrestrial C cycle; trends in DOC fluxes
from Scottish catchments; impacts of climate change on C storage in the Arctic, Antarctic and the UK; modelling the role of
biogeochemical cycles in glacial-interglacial periods and under climate change; and prevention of water supply discoloration from
DOC by land and soil management.
4.4 BBSRC-funded projects
BBSRC research includes standard research grants, studentships and Core Strategic Grants. Relatively little direct climate impacts
research is currently funded (impacts on ecosystems), although much research of potential relevance is available including modelling
(pesticide fate, fluid/solute/water transport, erosion, sediment losses, P losses, N 2O fluxes, farm woodland systems, S cycling and N
CSG 15 (1/00)
13
cycling), GHG fluxes (N2O and global warming potential of agriculture due to land use change and management), and SOM and
nutrient cycling (C and N mineralization, SOM dynamics, spatial variability and microbiology).
Specific relevant BBSRC research projects include Accelerates, using a crop growth model to investigate the impacts of climate
change on agroecosystems; modelling nitrous oxide fluxes at different spatial scales; development of a soil erosion model for
Southeast England climate impacts studies; development of a soil erosion model based on laboratory data; development of a
catchment scale P loss model; development of plot scale forest growth and forest soil C cycle models; a mathematical and
experimental study of soil structure and moisture heterogeneity for microbial biomass dynamics; the impact of land management
practices on the global warming potential of UK agriculture including the impact of climate change scenarios; development of the
WIMOVAC model to investigate the effects of elevated CO2 on soil sustainability and C and N mineralization; the development of a
global network of soil organic matter studies for investigating the impacts of land use change and management (SOMNET); and the
development of a dynamic S flux model sensitive to temperature and moisture. Relevant BBSRC studentships include the impact of
pharmaceuticals on soil functions and investigation of global soil C fluxes from land use and land management. BBSRC-funded Core
Strategic Grant (CSG) projects span a number of BBSRC-supported institutes and include uncertainty in process modelling; fluid and
solute transport; spatial variability; biological processes; transport processes; C cycling; multi-scale, multi-process statistics and
modelling; decision support system development for soil moisture and degradation; organic matter cycling; C, N and P mineralization
and modelling; models for pesticide fate and transport; SOM and microbial biomass ecology; N cycling and modelling in grasslands;
N and P leaching in grasslands; multi-scale dynamics and modelling of organic C in soils; C and N transformations in soil; modelling
the turnover of organic C in arable soils – development of the RothC model.
4.5 Environment Agency-funded projects
Relevant Environment Agency projects include MITCH, investigating flood defences under climate change; SUDS – debris flow and
land stability under climate change including soil moisture and runoff; the fate of radioactive waste disposal under climate change;
MONARCH, investigating changes in biodiversity under climate change; and umbrella projects on climate change adaptation and
mitigation (with a focus on sustainable energy).
4.6 EPSRC-funded projects
Relevant EPSRC projects include: biological and engineering impacts of climate change on slopes and embankments including
models, measurements and spatial soil properties; development of measurement methods for the impact of climate change on
landslides and soil clay strength; developing economic and social information for studying climate change impacts on the building
sector including urban drainage; developing a model for estimating climate change impacts on highway cuttings including soil
strength and permeability; CRANIUM, investigating climate impacts in the built environment, transport and utilities sectors including
urban drainage, slope stability and pollutant linkage; the adaptation of the urban environment to climate change including urban
greenspace; and developing better climate scenario data for urban areas which accounts for the heat island and heat source effects.
4.7 ESRC-funded projects
Relevant ESRC projects include investigating the impact of climate on UK agricultural productivity and output from 1984-1990;
modelling interactions between climate change, non-point pollution and land use; adaptation to rapid climate change; vulnerability to
rapid climate change in Europe; environmental and distributional impacts of climate change in Scotland including land cover,
biodiversity and modelling.
4.8 National Assembly for Wales (NAW)-funded projects
Only one relevant NAW project was found on the internet.
4.9 Scottish Executive Environment and Rural Affairs Department (SEERAD)funded projects
Relevant SEERAD funded research includes scoping studies on climate change impacts and adaptation in Scotland, on land use
change impacts on organic soils, and development of a model for C and N cycling in organic soils.
4.10 Conclusions and recommendations based on projects
Scientific findings from the research projects reviewed here can be classified into direct impacts on soils (for example, the effect of
increased temperatures on decomposition of organic matter) or indirect impacts (e.g. the effect that changing litter inputs from plants
could have on soil organic matter as a result of changing plant productivity driven by climatic changes). These conclusions are then
summarised for the core functions of soil identified in the UK Soil Action Plan, followed by general conclusions on current research
into climate impacts on soil functions.
Direct impacts. Assuming constant inputs of carbon to soils from vegetation, the impact of climate (in combination temperature,
precipitation and evaporation) could cause significant losses of SOC and organic matter from most mineral soils in the UK, with the
greatest losses expected in Southeast England, where rates of temperature increase are greatest. This could lead to poorer soil
structure, stability, topsoil water holding capacity, nutrient availability and erosion. However, these effects could be offset by
enhanced nutrient release resulting in increased plant productivity and hence litter inputs (and also see the later section on indirect
CSG 15 (1/00)
14
impacts). Relatively little comparative research has been done on organic soils, although scoping work suggested drying out of Welsh
bogs might occur in the absence of deliberate management intervention, resulting in increased GHG fluxes and thus a positive climate
feedback. In Scotland, areas experiencing increased rainfall could expect increased peat formation and methane release, whilst areas
experiencing decreased rainfall amounts could undergo peat, and hence CO 2 loss.
Changes in soil moisture content have also been predicted – including increased moisture deficit for arable crops (especially on
shallow soils) and for forest soils in Southeast Scotland.
Variable and largely unknown overall effects on pesticide fate and losses could be expected, due to the complex nature of interactions
between pesticides and the environment under a changing climate. For example, increased applications of pesticides could result
from increases in pests and diseases, although higher temperatures could cause more rapid degradation rates. Changes in rainfall
patterns could lead to increased losses via bypass flow and increased degradation in winter, but increased persistence could occur
during drier summer conditions, and increased transfer to groundwater could result from more intense and frequent storm events.
Increased winter rainfall, and particularly increased frequency and intensity of extreme rainfall events could increase problems with
land stability and landslips. Generally small effects on erosion were expected in Scotland, although increased erosion might occur
during winter. Increased rainfall could increase atmospheric N deposition to soils.
Flooding and subsidence could affect archaeological sites, and changes in wetland and waterlogged habitats could result in damage to
artefacts, although drier summer conditions would improve reconnaissance activities for archaeology.
Soil and vegetation changes might occur leading to degradation of sensitive arctic-alpine Welsh and Scottish systems.
Indirect impacts. The integrated impact of climate change is expected to generally increase crop yields (with winter wheat, sunflower
and sugar beet having been investigated in detail), as a result of the combined effects of CO 2 fertilisation, radiation use efficiency and
longer growing seasons. Increased sunflower yields might enable this crop to become competitive with oilseed rape in East Anglia.
Smaller increases in yield or possible decreases are expected for light soils in Southern England, and parts of Southeast Scotland
suffering increased water stress. Decreased yields could also be expected for potatoes in Cornwall, oilseed rape in South and
Southeast England and high quality horticultural crops in Scotland. Increased CO 2 concentrations should lead to greater plant
productivity. Increased temperatures might, however result in decreased yields (and hence litter inputs), although this would
generally be offset by the CO2 fertilisation effect. Increases in grass yields and forest growth are also generally expected. Reduced N
inputs to crops might be needed with the exception of some areas in Scotland where small increases in N inputs could be required. In
summary, increased productivity would generally lead to greater inputs of carbon to soil, thus increasing SOM. However, this
depends on:
a) how elevated CO2 changes the allocation of C above and below ground
b) harvest index of future crop varieties, and
c) how changes in temperature and moisture affect SOM turnover.
Reduced N inputs could result in lower N leaching, although this will also depend on how changes in rainfall and temperature affect
the N cycle and water movement.
Generally less work days would be available for arable land in autumn, spring and winter, which could have negative impacts on soil
structure, increase erosion, N2O emissions, and P, N, S and pesticide losses although again this would depend on interactions with
climatic changes. However, some western areas of the UK might experience an increase in work days. Greater irrigation of root crops
might be necessary, particularly for sugar beet and potatoes in East Anglia although there would be little need for irrigation for these
crops in the Northwest.
Possible land use changes could include reduced areas of arable land in East Anglia, conversion of upland grass to arable in the
Northwest, increased afforestation in Scotland and general increases in areas under barley and set-aside. More specialisation in cereal
and root crops is likely with more spring crops being sown in Scotland, with the crop ranges spreading northwards. Land use change
has considerable potential to alter soil properties. For example, changes in vegetation cover could alter runoff and nutrient losses as
well as SOM content. However, socioeconomic trends are likely to have a dominant role in determining land use patterns, thus
making general predictions problematic. Flooding and sea-level rise are likely to lead to a loss of arable land in low-lying and coastal
areas of England and Wales, whilst increases in arable land and woodland establishment on the floodplain elsewhere could increase
the risk of damage to archaeological remains.
4.11 Soils for agriculture and forestry
Soils for agriculture
A considerable number of research projects have investigated climate impacts on agriculture or forestry although few have focussed
on soils. Climate change will have a bi-polar impact upon agriculture. However the positive impacts of faster crop development due
to higher temperatures cannot be expected to persist, for example if temperatures continue to rise above the crop optimum. Higher
temperatures will negatively impact on agriculture, more specifically upon crop productivity/ suitability, through (a) a reduction of
soil organic matter contents, (b) changes in soil pH via local contamination caused by increased rates of leaching and agricultural
CSG 15 (1/00)
15
runoff, (c) increased chemical reaction rates, and (d) changes to the soil water balance through increased evapo-transpiration levels
(+5%) and plant uptake due to water stress. Where soil water deficits increase, crop productivity will suffer.
Other negative implications include the increased potential for soil sealing, soil erosion, poaching, compaction and land use change.
For example, soil wetness, water-logging, and flooding are all predicted to increase in winter. Soil sealing and compaction will result
in hard surfaces, poorer workability and ultimately resource extensive farming systems.
Decreased SOM could result from increased annual temperatures, with knock-on effects on soil structure, stability, water holding
capacity, nutrient availability and erosion. However, changes in SOM content will depend on interactions with changing plant
productivity (likely to increase), crop varieties and allocation. Information is lacking on the response of organic and organo-mineral
soils to climate change and it is hoped that the Scottish Executive/Welsh Assembly Government sponsored study due to report in
2007 will start to answer some of these questions.
There are certain threshold situations with fragile soils where even a small change in external conditions may cause an adverse change
from one dominant soil-forming process to another. Cumulatively, the ability of soils to support and sustain agriculture under
conditions of climate change is highly variable. In Wales, climate change could create opportunities for growing a wider range of
crops, for example maize, and increase the amount of land under arable production (currently less than 5% area). However, this could
lead to increased erosion in vulnerable soils and emission of carbon.
Less available work days in autumn, winter and spring are likely which could result in damage to soil structure and problems from
soil erosion, nutrient and pesticide losses and N2O fluxes. Consequently, any fieldwork will have to be well planned in terms of soil
moisture, the time available and the likely weather during and following the work.
Increasingly unpredictable springs are likely to continue. Coming out of a wetter winter, early fieldwork, such as spraying for wheat
bulb fly or Alternaria, will be more risky. Spring nitrogen applications will be vulnerable to increased risk of run-off from increased
rainfall, but temperatures will be higher and the season will start earlier. This may be good news for root growers with less bolting
risk for sugar beet and an earlier start for potato crops. Correct cultivation techniques and timing will be important to reduce the risk
of soil erosion from heavy rainfall.
Summers are likely to be drier and warmer, meaning less wet weather diseases like Septoria. The dry conditions will make combining
easier, but leave seed- beds very dry. This will mean that weed seeds will be less likely to germinate early on, reducing the ability to
deal with the threat of herbicide resistant weeds such as black-grass by using a stale seed- bed technique.
Autumn conditions will vary depending on location, but conserving moisture will be important. Soils will probably be drier at the start
of autumn and wetter sooner. Some land will still need to be ploughed rotationally, but the challenge will be to get autumn crops
established before heavy rainfall later in the autumn. There will be increased pressure on the time available for cultivations with more
land being too hard and dry to cultivate efficiently after harvest. Whilst it may be necessary to wait until some rain has occurred, the
work will need to be done in a shorter time. This situation suits conservation tillage techniques which move less soil at shallower
depths, conserve moisture, facilitate better rooting and allow faster output. However, the onset of earlier wetter conditions in autumn
may mean the plough is needed for later crops, or a shift to spring drilling on more difficult heavy soils.
There is a risk of a rise in cultivation and crop protection costs due to less time being available for autumn crop establishment.
However, it is important that growers adhere to good soil care principles to protect both soil and the environment from changes in
climate.
In order to mitigate against the effects on cropping which may arise from climate change it will become necessary for farmers to pay
closer attention to their soil structure. With longer periods of hotter and drier weather and spells with greater rainfall, the ability of the
soil to buffer these events may be critical for soil and yield preservation. A soil which is able to absorb more water during periods of
heavy rainfall will reduce the likelihood of runoff while replenishing water reserves deep in the soil structure. The crop can then draw
upon this water during dry conditions. This provides a more cost effective solution to providing adequate water to crops during
drought than building reservoirs and irrigation systems.
It is likely that increased pesticide use will occur in livestock farming, for example increased used of sheep dip/pour-on synthetic
pyrethroids (SPs) and organophosphates (OPs) to prevent blowfly strike, scab, ticks, mites infection.
Similarly, there could be increased endo parasite infection (for example. liver fluke, gutworms), if climate change helps that part of
the parasite life cycle that occurs outside the host leading to increased use of veterinary products such as Ivermectin. The effects of
Ivermectin, SPs and OPs on soil invertebrates are well documented and as well as direct (for example dung beetle, tipulid larvae) and
indirect (for example upland wading birds) biodiversity, effects could be potentially damaging to other soil functions, for example
soil, air, water interaction, and perhaps less so for food and fibre production.
Soils for forestry
As for other land covers, the impacts of climate change on forest soils cannot be reviewed in the absence of a discussion of the effects
of climate change on both the trees that are supported by forest soils, and the wider land management issues of the forestry industry.
Both climatic warming and rising CO2 levels in the atmosphere will enhance tree growth in the short term. However, no UK-based
CSG 15 (1/00)
16
research has corroborated these contentions in the longer term or for mature canopies, with current predictions based on a
combination of impact studies on young trees and modelling studies. Globally, research findings on the effects of rising CO 2 levels
have been equivocal, with the limited number of studies indicating rather small increases in growth rate and minimal impact on soil
carbon stocks (Oren et al., 2001). However, the limited number of such studies means that generalisations cannot be made since they
deal with specific forest types on specific soils. The hypothesis is that in the longer term, increased tree growth may accelerate the
depletion of soil nutrient pools, which will lead to subsequent growth reduction in second/third rotations and increased leaching and
soil acidification. Changes in growth will also affect the amounts and quality of leaf production and litter inputs to the soil, thus
having an effect on the soil nutrient pool. Rising CO 2 levels have also been shown in some studies to alter the C:N ratio of leaf litter
which would be expected to reduce decomposition rates.
It is also likely that the combination of increasing CO2 concentrations, changing patterns of N deposition and climatic warming
temperatures have had a positive, non-zero effect on forest growth, both in Britain and across much of Europe. At present, it is not
possible to quantify the relative contributions of these three environmental drivers, while changes in management practice and
planting stock add to the uncertainty associated with growth trend analysis. Specifically in the UK, the age structure of the forest
estate further complicates interpretation of changes in growth rates.
Given that CO2 levels and temperatures are set to rise above current levels in the coming decades, it may be expected that forest
growth rates in Britain will continue to rise, except perhaps in areas prone to summer droughts or nutrient limitation. Nutrient
limitation induced through enhanced tree growth could be exacerbated by wetter and milder winters increasing nutrient leaching and
reducing nutrient cycling. If elevated CO2 increases tree leaf area, this will have implications for water supply to the soil, which will
decrease due to higher precipitation interception losses. Changes in leaf area will also affect the litter input to the soil. Forest floor
microclimate may also be altered as a result of increased or decreased litter input to the soil and increased/decreased light interception.
Soil disturbance may occur as a result of windthrow if the size and proportion of storm events increase. Any increase in winter
waterlogging due to higher winter precipitation may further promote windthrow. It should, however, be borne in mind that predictions
of changes to the wind climate are far from certain and robust predictions of changes to the incidence of both wind snap and
windthrow cannot be made. If forest soils are waterlogged for longer periods in winter, access for forest management would be
limited. If good practice guidelines are not adhered to, then an indirect effect of climate change would be soil compaction and a
deterioration in soils structure.
Increase in temperature, and particularly in a combination with drought, will increase the risk of fires in forestry, with consequent risk
to soil organic layers. The magnitude of carbon emissions resulting from forest fires will be dependent on the intensity of the fire,
which in turn will be a function of the quantity of combustible material. Knock-on effects could include changes in water holding
capacity as a result in loss of organic matter.
Soil erosion is an area of current concern that could be affected by climate change. Increased winter rainfall would be expected to
increase erosion on susceptible sites, particularly where tree cover is absent following windthrow or clearfell, for example. Changing
management practice, such as the uptake of alternative to clearfell (ACF) methods of management may mitigate some of the effects of
climate change as discussed in section 10.
If the recent trend of rising DOC continues as a result of increasing winter rainfall, together with higher soil temperature, this would
have implications for water quality. Changes in DOC leaching would also warrant consideration in carbon budget studies.
The effect of climate change on the greenhouse gas balance of forest soils is an area of considerable importance, but also uncertainty.
This is particularly the case for organic soils. Rising temperatures would be expected to increase soil respiration (and thus the
oxidation of organic soils), while changing evapotransipration and rainfall distribution would be expected to lead to changes in the
water table and consequent effects on methane and nitrous oxide fluxes. Considerable interactions with landscape and forest
management would be predicted and warrant consideration.
Mycorrhizae play an important role in nutrient cycling in forest soils and have also been shown to confer some protection against soilborne pathogenic fungi. Pollutant deposition, atmospheric CO 2 levels and soil temperature and water content have all been shown to
affect ecto and endo-mycorrhizae. However, effects of climate change on the strength of these associations and their effect on tree
performance has not been well documented.
4.12 Interactions between soil, air and water
A number of research projects have investigated climate impacts on soil, air and water interactions. Protecting the capacity of soils to
store, transform, and regulate processes between itself, air and water is critical to environment sustainability. Four interrelated
scenarios are presented from existing research detailing the implications of increased temperatures and CO 2. Firstly, increased Net
Primary Productivity (NPP) will result in greater returns of carbons to soil. Secondly, increased NPP may actually deplete soil
nutrients through increased plant growth and soil fertility may actually decrease. Thirdly, increased decomposition at rates that are
likely to outstrip NPP leading to reduced soil organic matter contents may occur resulting in the role of soil as a carbon sink changing
to one as being a carbon source. As soils contain twice as much carbon as the atmosphere, a small change in the soil CO 2 budget has a
disproportionate effect on the climate. Lastly, increased soil temperatures have implications for soil biological activity – when it
becomes too high the decomposition capability of bacteria may be reduced due to limited soil moisture levels resulting from increased
evapo-transpiration rates ultimately reducing biomass growth and soil fertility.
CSG 15 (1/00)
17
Reduction of soil respiration in response to drought and increased soil respiration in response to warming including rhizosphere
respiration, will have implications for CO2 fluxes.
Warming will also decrease soil organic matter, increase CO 2 emission, increase litter decomposition and N mineralisation rate, which
may have implications for nitrogen leaching especially in N saturated systems. It has been hypothesised that in the long term the soil
carbon stocks will be insensitive to temperature under some circumstances. This is based on the assumption that soil physico chemical
“stabilisation” reaction may respond more to warming than microbial decomposition/respiration reactions. In turn, warming may
increase the rate of physico-chemical processes which transfer organic carbon to more stable carbon pools. As a result total soil
carbon loss may be very small and even may increase.
Elevated CO2 will increase not only above-ground biomass, but also below-ground tree biomass and fine root turnover and thus will
increase the total carbon flux to the soil. In addition, elevated CO 2 may decrease N in leaf litter and increase leaf litter lignin content,
which on the other hand will slow the decomposition rate. The timescale for the above processes and effects to take place is unsure
together with the effect of CO2 which in the shorter term may be positive to soil C, but the reverse in the longer term.
Soil moisture deficit may significantly increase in northern, middle and southern England in comparison to Scotland where there may
be even slight decrease. Southern England is the most sensitive area to reduction in precipitation and drought. Clay soils will be more
vulnerable in comparison to loams and sands. Cracking of clays will encourage bypass flow and increase the risk for ground water
contamination especially on N rich soils. Seasonal fluctuation in soil moisture may be largest in southern England and more in clay
soils. The higher the seasonal fluctuations in soil moisture, the higher the risk of drastic changes to soil chemistry occurring, e.g.
higher leaching of nutrients/pollutants, soil acidification, gradually lower soil cation exchange capacity and thus lower soil buffering
capacity. Drying out of peatlands will have its implications for CO 2 fluxes and may convert peatlands from CO2 sink to CO2 source.
Increasing winter temperatures will contribute to general increase in Green House Gases (GHG) emissions. Water cycling will also be
affected, which may lead to earlier soil nutrient exhaustion due to higher and prolonged microbial activity in the soil. Higher winter
temperatures will encourage pests and diseases which may increase the need for, and the amount of, pesticides applications.
Higher winter rainfall will increase runoff, soil erosion, N 2O production and emission. In the longer term, some wet soils may become
permanently waterlogged which will increase their CH 4 emissions soils. Wetter soils increase the risk of windthrow in forestry,
followed by possible soil degradation.
Changes in climate will induce change in nutrient cycling and may impose higher risks for ground water contamination (especially in
more fertile soils) as a result of increased leaching due to flushes of nutrient in soil solution by heavier winter rainfalls and possible
storm events. In poorly buffered soils, change in precipitation will have an impact on soil acidity. Increasing summer temperatures
will affect the soil moisture and increase the drought summer periods, which will encourage build up of nutrients and pollutants in the
soil. Thus, the autumn nutrient flush will be greater.
Climate changes will impact on the critical loads for acidity and nutrient nitrogen and their exceedances in the UK and in Europe.
Higher temperatures, changed precipitation patterns and modified net primary production generally would increase the critical loads,
although a decrease may be expected to be observed in mountainous and arid areas. When comparing the critical loads with the
deposition of sulphur and nitrogen, the critical load exceedances may decline.
UK forest soils are a sink only for about 1% of all methane emissions per year. Factors that affect CH 4 emission by soils are those that
affect: 1) gas diffusion in relation to oxidation/reduction potential and methane transfer; 2) microbial activities in general:
temperature, pH, redox potential, substrate availability etc. 3) methanogenesis and competition with denitrification and sulphatereduction processes.
Soil with a high water content promote methanogenic activity and reduces methanotrophic activity by reducing the size of oxidised
zones. Upland soils, which become temporarily waterlogged, may become CH 4 sources. CH4 consumption in forest soil is negatively
related with soil water content. Drier soil conditions will encourage the CH4 consumption in soils.
4.13 Soils and biodiversity
Very few UK projects have investigated climate impacts on soil biodiversity. No papers or projects were found that specifically
investigated the impacts of climate change on forest soil biodiversity. It is recognised that whilst a great deal of work on above
ground biodiversity has been carried out, little has been aimed at below ground communities and groups/species. The likely impacts
under consideration were confined to moisture and temperature changes.
4.14 Soils, the landscape and cultural heritage
Very few UK projects have investigated climate impacts on soils, the landscape and cultural heritage although several scoping studies
have considered relevant issues. Threats to soil and soil quality endanger the sustainability and protection of the historic landscape.
Land use change and vegetation cover/ species composition change driven by environmental/ socio-economic factors will also have
implications upon the landscape.
CSG 15 (1/00)
18
Heritage sites will suffer from an increased rate of chemical/flooding risk on certain structures and fabrics. Higher levels of soil
moisture could increase biological attack and other forms of decay such as salt mobilisation. Historical gardens will become
increasingly expensive to maintain under the impacts of climate change and growing conditions. Degradation of waterlogged soils
may expose some previously buried artefacts to the air resulting in reduced survival of remains. The increased risk of poaching will
continue as major source of damage to archaeological sites.
Any changes in climate which increase soil erosion risk on agricultural soils will potentially affect archaeology - as any thinning of
the soil will leave buried archaeology more vulnerable to damage from agriculture etc.
Any changes which cause changes in flora/trees etc. will change the look of the historic landscape and any changes in climate which
lead to the lowering of the water table will affect the preservation of waterlogged archaeological remains, particularly in wetland areas
where archaeological preservation can be spectacular if waterlogged. This can also cause peat erosion which will cause buried
archaeological landscapes to emerge and be vulnerable to damage from further erosion and agricultural activities. Any climate
change which causes the growing of new agricultural crops could, if these crops have roots which penetrate further into the soil, or
require more extensive/deeper cultivation/soil preparation techniques, lead to damage to below-ground archaeological remains.
Extremes of high and low temperature could cause damage to artefacts within the plough soil. If, as is predicted, intensive arable
cultivation could shift from the south east to the north, buried archaeological sites currently not at risk from arable damage, could
become so.
4.15 Soils in mineral extraction, construction and the built environment
Some projects have been conducted on climate impacts on specific aspects of construction and the built environment although very
little has been done on mineral extraction. Increases in winter rainfall, particularly the magnitude and frequency of intense events
could have negative impacts on land stability and give rise to landslips. Increased subsidence and problems with drainage and
flooding are likely. Climate change will also affect housing development plans as current ‘preferred locations’ may become unsuitable
for development.
Provision of soil at restoration may be inadequate for future uses expected of it, especially if there remains a policy to automatically
replace land-use like-for-like. This issue will be greatest on containment landfills and remediated brownfield sites where treatment
techniques like containment or solidification prevent root penetration below the depth of soil provided. Climate change facilitates a
radical revision of sustainable after-uses, including deliberate choice of xeric species. Soils composed of textures at the ends of the
textural triangle are likely to be more susceptible to the increased seasonality of predicted rainfall pattern. For example, there will be
increased management issues for clays which are harder for longer in summer and of low bearing strength for longer in winter.
Similarly, sands may behave more ‘quickly’ in winter whilst retaining less plant available moisture in summer.
Increased droughtiness will increase the likelihood of shrink-swell in soils containing shrink-swell clay minerals. There will be
possible disturbance to building foundations, and need for underpinning/repair. Increased soil temperatures may exacerbate chemical
attack to foundations. In addition, vegetation, notably trees, may be discouraged on clay soils in urban areas, because of the view that
they exacerbate the problem. There is a potential risk to engineered structures based on clay caps (e.g. in containment landfills), with
consequent likelihood of increased leachate generation and release of landfill gases. Although there has been great reduction in
methane emissions from landfill sites in England, Scotland and Wales (about 63 %) landfill sites are still the second largest (after
agriculture) methane emitter in the UK. Vegetation is likely to suffer severely where soil depth is limited by compaction or
engineered structures – trickle irrigation may need to be provided where appropriate, though water resources will be stretched in south
and east England. Changes in landscape architectural practice will be needed, with greater reliance on drought tolerant species. Use
of compost to help increase available water capacity will appear attractive, though this may be difficult in practice. Weed control will
be vital when establishing new tree and shrub stock. Changes in barometric pressure may become more pronounced, with potential
risk to landfill sites, where explosive landfill gas may be emitted during passing of low-pressure weather systems.
Droughtiness, followed by rainfall, may also cause the increased release of metals and pollutants into soil and stream water. Episodic
phenomena should be taken into account when assessing the suitability of contaminated and remediated soil media as final cover.
Soils which exhibit significant shrink-swell behaviour may be at greatest risk from promoting contaminated ‘by-pass’ flow to
groundwater, and may be more prone to water erosion.
Increased flooding and larger rainfall events will pose an elevated risk of soil erosion, though this is unlikely to be an issue in practice
(most urbanisation is on level or gently sloping land, and bare soil is rare). The greatest potential danger will occur on brownfield
land where soil materials may be contaminated, and where erosion could lead to pollution of surface waters. Increased risk of
flooding may be remedied by changes in engineering infrastructure, and by provision of greenspace to provide ‘overflow capacity’.
This will require provision of soil materials capable of supporting vegetation, and may require improved technologies for remediation
of contaminated soils to supply such materials on brownfield land. Land to be used for temporary flood drainage must be underlain by
soils with suitable infiltration capacity and hydraulic conductivity, and must not be erodible.
Elevated temperatures will encourage organic matter mineralisation, though it is difficult to envisage this as a significant issue within
the built environment. Increased nutrient uptake as a result of increased temperatures and atmospheric CO 2 concentrations may lead
to soil infertility, and need to return of organic wastes as composts to the urban soil. Higher temperatures will also encourage
volatilisation of some organic pollutants, and mercury, on contaminated sites.
CSG 15 (1/00)
19
5
Make use of wide stakeholder consultation
A Stakeholders Workshop was arranged on April 5 th 2005 in London. Twenty five people attended and took part in break out groups
that focussed on the impact of climate change on particular soil functions. A questionnaire, based on the same ideas, was circulated to
people not participating in the workshop. The conclusions from both exercises have been included in the review and are summarised
in Appendix Tables 1 to 5 according to different soil functions.
6
Potential risk management practices and climate-proofing
It was decided to combine the two objectives relating to mitigation and adaptation (namely, Identify potential risk management
practices (including non-agricultural land-management practices) and Identify practical measures that land managers might consider
to climate-proof soils in the later stages of soil management plans for agriculture, but will also examine other implications of climate
change for management of the various land types (agriculture, forestry, built environments, disturbed environments) into one section
for the purposes of this report.
Climate change adaptation measures related to agricultural soils








Informed decision making regarding the timing of agricultural operations, the type of operations used (e.g. minimum tillage), and
by erosion control measures such as buffer strips could help reduce negative impacts on soil structure, erosion and runoff..
Soil moisture conservation measures such as mulching and minimum tillage could help minimise increased crop irrigation needs
in summer.
Careful planning of the amounts and timing of applications of fertilisers and pesticides could help minimise increased nutrient
and pesticide losses in winter.
Land management practices to increase SOM content (e.g. addition of cereal straw, animal manure, rotations etc) could help
maintain SOM contents and avoid increased CO2 fluxes from soils.
Careful planning of land management (e.g. timing and application of fertiliser applications) could help minimize potential
increases in trace gas fluxes from soils.
Conservation measures to maintain peatland moisture could help avoid drying out of peatlands and associated CO2 fluxes.
Coastal management options should consider measures to protect aquifers from saline intrusion due to sea level rise where
appropriate.
Conservation measures for low-lying vulnerable coastal habitats need to be planned carefully with consideration of possible
impacts on trace gas fluxes.
Potential agricultural risk management practices








Avoidance of the negative impacts of increased winter precipitation and intensity on soil structure, erosion and runoff could be
achieved with careful decision making regarding the timing of agricultural operations, the type of operations used (e.g.
minimum tillage), and by erosion control measures such as buffer strips.
Increased crop irrigation needs in summer due to decreased rainfall and increased soil moisture deficit could be achieved through
soil moisture conservation measures such as mulching and minimum tillage.
Avoidance of increased nutrient and pesticide losses in winter from increased winter rainfall amounts and intensity could be
achieved with careful planning of the amounts and timing of applications of fertilisers and pesticides.
Reduced SOM contents and increased CO2 fluxes due to increased temperatures could be mitigated using a range of practices to
increase SOM content (e.g. addition of cereal straw, animal manure, rotations etc.).
Potential increases in trace gas fluxes from soils could be mitigated with careful planning of land management (e.g. timing and
application of fertiliser applications).
Drying out of peatlands caused by reduced summer rainfall and increased temperatures could be mitigated by conservation
measures to maintain peatland moisture.
Coastal management options should consider measures to protect aquifers from saline intrusion due to sea level rise where
appropriate.
Conservation measures for low-lying vulnerable coastal habitats need to be planned carefully with consideration of possible
impacts on trace gas fluxes.
Potential forestry risk management practices
Main issues associating with the risk management practices in forestry for land managers are:
 better use of the UKCIP decision-making framework to predict the risks and track the impacts of climate change and
 raised awareness of all risks related to climate change impacts in the forest sector and forest soils. The climate change
management adaptation measures related to forest soils are summarised in Section 8.
Climate change adaptation measures related to forest soils
In the forestry sector there are a number of management practices which can be modified to reduce the potential impact of climate
change.
CSG 15 (1/00)
20










Harvesting – Whole Tree Harvesting (removal of tree stem plus all branches and foliage) should not to be practised where soils
are infertile. Thinning needs to be planned according the site-specific risk of windthrow and postponed if necessary. A reduction
in the intensity of forest harvesting, where possible, will reduce the soil disturbances by logging equipment. Overall, it is very
important to consider the sensitivity of a site to any harvesting type very early in the planning stage. Further research and
guidance seem necessary in this area.
Tree species suitability – Species choice, species mixtures and the possible use of seed origins better adapted to climate change
will need to be considered carefully before tree planting. Species with greater drought tolerance may be needed, especially in
south and east of England, with deep root systems and low leaf area. Choice of inappropriate species will pose risk to soil
fertility through reduction of organic inputs as litter.
Fertiliser (including sewage sludge) and herbicide application – There must be a recognition of greater unpredictability of
extreme events. This will increase the need to plan well for application activities, to prevent loss and pollution risk with
following storm events.
Forest fires – will become more prevalent, with risk to soil, especially fertility if organic topsoils are burnt off. There will be a
greater need for vigilance, through forest fire monitoring, and an increase in consideration of forest fire risk in the planning of
forest design and medium to long term harvesting planning. Risk of forest fires may require a review of brash management
policy and practice. However, risk must be assessed alongside other management issues, because adaptation measures may pose
risk to habitat management policies and practices.
Ground preparation – in the lowlands, ground preparation practices may need modification to maximise tree establishment by
placement of tree transplants at bottom of furrow, rather than on plough ridge. Carefully choosing the appropriate cultivation
techniques can produce major beneficial changes in the temperature regimes on a wide range of soil types.
Drainage – drainage systems must be redesigned for more frequent extreme events where these are predicted to occur. Culvert
design is a real issue in some parts of Britain now, and inattention could lead to greater frequency of wash-out events with
consequent increase in sediment movement to surface waters.
Tree establishment – Irrigation may be necessary in drier parts of country during the first three to five years of tree
establishment, notably in urban forestry schemes. Soils may benefit from incorporation of organic matter (e.g. composts) to
increase available water capacity before tree planting on some ex-agricultural sites. Weed control may need to be more exacting
in those parts of the country where droughtiness will become particularly severe in the spring and early summer months.
Changes in Land Use – e.g. drainage and afforestation. Tree establishment on former arable or grassland may help to reduce the
carbon loss from soils. More research is needed to explore the consequences to soil when land use changes and then use this
knowledge to guide management practices to adapt to the expected climate change.
Education/behavioural – Raise awareness to people of all ages of the predicted changes in climate and the potential impact on
the soils and environment as a whole. Build the concept of adaptation into education schemes and include the likely positive
benefits of woodlands and forests in ‘downstream’ environmental effects of climate change, e.g. in flood prevention, pollution
mitigation.
Keep a ‘watching brief’ – in changes in the UKCIP scenarios and amend guidelines and directions for research and practices
according to these climate change predictions.
8
Identify suitable soil reference sites, including those where
different vulnerabilities are evident now.
Long –term intensively monitoring systems are providing a unique opportunity to study the effect of climate change on soil functions.
Under such monitoring programs many interactive factors and environmental variables are monitored, so various interactions can be
taken into account when evaluating the effects of climate on the soils. Changes in time are also recorded which provide excellent
datasets for dynamic model inputs and calibration. The various existing soil monitoring schemes in England and Wales were
reviewed in Defra project SP0515. In addition to the four datasets that form the main focus for that study there are other sources of
systematically collected soil information (Table 4). Topsoil and subsoil data for many parts of the UK have been collected by the
British Geological Survey (BGS) and are included in G-BASE. In Scotland soil data are available from the Macaulay Land Research
Institute (MLURI). The National Soil Inventory carried out in Northern Ireland is maintained by DARD. In addition, some of these
are European based monitoring networks (e.g. Level I and Level II) providing the opportunities for cross climatic related research.
Generally, they cover various land uses and are set up to have good spatial and soil cover, so are very representative of sites/soil with
different vulnerabilities to climate change.
Table 4 Summary on value of UK soil monitoring schemes in identifying effects of climate change on soil
function
Countryside Survey 2000
Environmental Change
Network
Forestry Commission level I
CSG 15 (1/00)
Advantages for use in monitoring effects of
climate change
GB wide information
All land use types
Time sequence of site and limited soil data
Linked to site measurements of climate
Continuing information on management
Time sequence of soil and site data
UK wide linked to EU network
21
Disadvantages for use in monitoring effects
of climate change
Not linked to site measurements of climate
No continuing information on management
Limited number of sites
No arable sites
No built environment
Forest sites only
sites
Forestry Commission level II
sites
British Geological Survey
Information system
National Inventory points for
Scotland
National Soil Inventory for
England and Wales
National Soil Inventory for
Northern Ireland
Representative Soil Sampling
System
UK wide linked to EU network
Forest sites only
UK wide information
All land use types
Some data from built environment
Extensive measured database
Detailed profile information
All land use types
Extensive measured database for topsoils
Detailed profile information
All land use types
Extensive measured database for topsoils
Time sequence of data
Detailed profile information
Extensive measured database for topsoils
Time sequence of data
No time sequence
Not linked to site measurements of climate
No continuing information on management
No time sequence
Not linked to site measurements of climate
No continuing information on management
No continuing information on management
Not linked to site measurements of climate
Not linked to site measurements of climate
Permanent grassland sites only
Not consistent site sampling
Agricultural sites only
No SOC
Not linked to site measurements of climate
No continuing information on management
9
Identify knowledge and/or research gaps and prioritise them in
terms of policy and stakeholder needs
General issues
There have been very few climate change impact studies directly focused on soils or soil functions – more research specifically aimed
at soil functions under climate change is recommended.
Relevant projects reviewed had considerable potential to additionally consider direct or indirect impacts of climate change on soils
although relatively few projects actually did so (for example, research considering changes in crop yield could readily be linked to
impacts on soil organic matter, moisture status and nutrient cycling). Thus it is recommended that, wherever possible, climate
impacts research not directly focussed on soils should incorporate a consideration of possible soil impacts.
The majority of research projects reviewed made their assessments using the UKCIP98 climate scenarios. These scenarios have since
been replaced with the state-of-the-art UKCIP02 climate scenarios. Thus it is recommended that research using UKCIP98 should be
updated using UKCIP02 – or at the very least, an assessment of possible changes to research conclusions should be undertaken.
Considerable funding and research effort has been directed into developing a suite of modelling tools for various soil functions and
processes (for example, pesticide fate, water relations, nutrient cycling and GHG fluxes). In combination with UKCIP02 scenario
data, these models would have great potential for assessing the impacts of climate change on soil functions in the UK although these
models have not yet been used extensively to this end. Thus research investigating the use of currently available soil process models
for climate impacts studies should be encouraged.
Few impacts studies (whether considering soils directly or not) consider the impacts of uncertainties in climate prediction and soil
process model formulation and parameterisation on soil processes. Those studies which do exist often only investigate a small
number of marker scenarios. Future research into soil functions under climate change should therefore attempt to deal with
uncertainty analysis where possible.
Soil, climate, vegetation and water are intrinsically linked and as such a meaningful assessment of climate impacts on soil functions
requires integrated, holistic modelling studies considering all of these (and other) elements. However, very few fully integrated
impacts studies such as REGIS have been performed. Thus research into developing and applying integrated assessment tools should
be supported.
There is generally poor integration between research projects both within and between research funding bodies – although
considerable added value could be achieved for relatively little effort in this manner (e.g. Defra CC0339 and CC0242). It is therefore
recommended that means of improving project integration are improved.
Where relevant, it is recommended that all new soil science research projects should consider climate change impacts where possible.
CSG 15 (1/00)
22
Information available from the internet on research projects is generally poor, especially regarding details of aims, methods, results
and reports. This hinders using ‘grey literature’ for climate impacts assessments and thus efforts should be made to improve
availability of information on UK research projects on the internet.
Considerable effort has been directed into long-term monitoring studies (e.g. long-term experiments and ECN). Where relevant, these
should be used as fully as possible for benchmarking and for guiding new monitoring work to assess climate impacts on soil
functions.
Relatively few projects have investigated the effects of elevated CO2 on soil functions (directly or indirectly, and interactions with
changes in temperature and rainfall) and further targeted research is recommended.
The impact of land use changes and socio-economic factors may be as important as the direct impacts of climate change on soil
functions, particularly for agriculture and thus studies integrating these elements should be encouraged.
Studies considering agriculture have dominated research although few studies on changes in soil biodiversity, soil/landscape/cultural
heritage issues and soil/mineral extraction issues under climate change have been conducted and thus more research into these areas,
and into multi-sector studies is recommended.
Although the reviewed projects have spanned many soil parameters and processes, SOM and soil C have been most widely
investigated and relatively few studies have considered multiple soil parameters or processes.
Soils for agriculture and forestry
Table 4 Adaptation type in relation to soils for agriculture and forestry
Adaptation type
Urgent
Long term
Watching brief
Share Loss
Hedging of land management
(mixed enterprises)
Change in regional cropping
patterns
Monitoring of adaptation
success, and need for
modification
Bear loss
Hedging of land management
(mixed enterprises)
Productivity loss (including
reduced intensity); Change in
regional cropping patterns
Ditto
Prevent effects: structural and
technological
Targeted woodland expansion;
Irrigation reservoirs
Adopting new enterprises and
land management systems.
Ditto
Prevent effects: legislative,
regulatory and institutional
Introduce instruments which
encourage soil management
planning; use woodland grant
schemes (make soil-proof)
Landscape and catchment
management (w.g. through
WFD)
Ditto
Avoid or exploit change in risk
Adaptive enterprises/land
management
Changes in regional cropping
pattern
Ditto
Research
Species and clonal studies in
relation to predicted climates;
including climate change
scenarios into ecosystem
process modelling; integrating
soil into ecosystem models
Research platforms for new
enterprises through DSS;
support from new agency?
Make full use of existing
monitoring networks to
examine how they could be
adapted to study effects od
climate change
Education/behaviour
Soil and Water Management
diploma courses; soils
education and awareness
(through schools, stakeholders
and media)
Continual education about
climate change and man’s
ability to affect it and need to
adapt to it. Need to educate
public on risk assessment.
Impacts on soil, air, water interactions
Table 5 Adaptation type in relation to climate change impacts on soil, air, water interactions
Adaptation type
Urgent
Long term
Share loss
Increase insurance for
flooding
Bear loss
Accept some flooding –
floodplains, managed retreat
CSG 15 (1/00)
23
Watching brief
Monitor effects of Sea level
rise
Prevent effects: structural and
technological
Pollutants – fertilisers and
pesticides
Consider crop irrigation
schemes; build flood
defences
Prevent effects: legislative,
regulatory, institutional
Introduce policies on
nutrientand pollutant
management, GHGs
Planning for flooding;
agricultural policies to reduce
runoff
Avoid or exploit changes in risk –
change location or other avoidance
strategy
DSS for pollutant loss, GHG
Consider crop irrigation
schemes
Research
DSS to inform what is
needed and whether it is
needed: pollutants, erosion,
water, GHGs, crops, forests
Education/behavioural
Modify people’s water use
behaviour;
Modify land use according to
suitability; reconsider tree
species suitability; climate
proof forest management
practices and fire risk
management
Biodiversity
The general framework of the discussion at the Stakeholder Workshop considered:
1. Effects on below ground conditions and diversity;
2. Effects of (1) which affect above ground diversity;
3. Effects on agricultural and other land practices which affect (1) and (2).
For the purposes of the discussion, current biodiversity was seen as the number of species/individuals tied to “characteristic” habitats,
for example Lowland Heath.
Issues of catchment level planning were critical to planning for change, encompassing issues of connectivity and ecosystem service
provision (De Groot et al, 2002, and the Millennium Ecosystem Assessment). The question was posed – are these appropriate for a
changing environment? The range of diversity present in existing sites, both between and within species may not be sufficiently wide
to encompass traits essential for a changing environment, depending on the speed and amplitude of those changes.
It was felt that there are so many “maybes” in the UKCIP scenarios that a focus on conservation of current characteristic systems is all
we have to work with – but accept that these may not be entirely “future proof”. This may entail careful extension of conservation
into ecological restoration.
A number of relevant impacts on biodiversity were identified:
 Changes in peatlands are likely (possibly drying out of Welsh bogs unless managed)
 Degradation of arctic/alpine systems
 Reduced SOM could affect soil biodiversity
 Loss of habitats from sea level rise and flooding. Wetland losses resulting from sea level rise will have profound implications for
biodiversity. Microbial activity will also experience a survival of the fittest regime as soil and air conditions change.
 There is a risk of change to biodiversity in suitable habitat for wet loving plant communities.
 Changes in soil moisture, temperature, organic matter and physical properties will inevitably change soil biodiversity.
 Changes in soil nutrient status, temperature and moisture could affect soil microbial diversity and functions.
These scenarios might not only affect the bio-physical conditions, but also affect enterprise choice and the “workability window”,
which would feedback to further alter the biophysical template. A change in climate may increase the “fragility” of these systems
such that a relatively minor “tweak” in management practice or crop choice could lead to catastrophic losses.
There are likely to be changes in the soil leading to impacts on biodiversity – more or less N for example. It is not clear that past
research into climate change effects on plant communities has addressed future landscape scenarios or below ground impacts – e.g.
use of warming cables does not prevent immigration/emigration of below ground species, and are therefore of limited application in
this regard.
In summary there are likely to be simpler soil systems if the loss of “old climate species” is not matched by recruitment of “new
climate” species.

What are the characteristic soil biological assemblages, functions and activities along a gradient of poor to good soil function?
CSG 15 (1/00)
24












It is clear that recent research into symbionts, antagonists, herbivores, and pathogens were critical in determining the nature of
above ground plant communities and little or no work has been carried out with respect to potential climate change effects on
these interactions.
How will farmers respond to changes in soil characteristics and workability?
Is soil response to eutrophication affected by climate change?
How will biodiversity respond to change in the soil climate and characteristics?
What effect will there be on below ground food resources?
Impacts on other trophic levels and their interactions require further investigation e.g. drier soils; do worms burrow deeper to
escape – less food for birds?
What is the impact on soil biodiversity generally?
Is it possible to reform aspects of CAP to target soil structure and function directly?
We need to be able to characterise soil functions sufficiently to measure such impacts.
Is it possible to conserve/restore all ecosystem characteristics under a changing climate regime?
Should we look to be conserving ecosystem services and soil functions free of metrics tied to particular species?
Should we be aiming for enhanced abiotic and biotic heterogeneity?
Soils, the landscape and cultural heritage
There has been little research on the effects of climate change on the varied physical aspects of the historic environment at the
landscape scale, and this could be undertaken using tools developed for other soil functions, notably food and fibre. There is a
relatively urgent need to use UKCIP scenarios to examine possible effects at a local, regional and national level, based on modelling
and GIS technology. Research sites should also be established to monitor changes and impacts. Again, a subset or extension of
existing intensive monitoring plots (e.g. ECN, Level II) could be adapted further to study effects on buried artefacts, and key
vegetation types. There is also a need to evaluate the social acceptance of heritage loss and changing aesthetics as likely climate
change effects make their mark.
Table 13. Adaptation opportunities for climate change impacts on soil, landscape and cultural heritage
Adaptation type
Urgent
Long term
Share loss
Identify wetland heritage
sites where sustainable
management is a possibility.
Prioritise others for rescue
conservation where
appropriate
Increased erosion of heritage
features due to loss of
vegetation and increased
flood and storm events
Bear loss
Manage vegetation and
drainage to reduce water
uptake from wetland heritage
sites and competition from
ancient trees.
Prevent effects: structural and
technological
In depth review and
guidance on soil and
hydrological management
for heritage sites
Application of water and
erosion control systems
Prevent effects: legislative,
regulatory, institutional
Develop a multi-agency
strategy for managing the
historic environment during
climate change
Protect some sites from
adjacent land-use change or
development which could
exacerbate impacts
Avoid or exploit changes in risk –
change location or other avoidance
strategy
Review potential impacts
and consider on what types
of heritage features they may
be limited. Identify sites
now, which are perceived to
be most at risk and develop
mitigation strategies.
Increase the value of
sustained archaeological
wetlands by identifying other
site opportunities such as
ecological habitats.
Monitor changes and review
mitigation strategies
Research
Research the effects of
climate change on the varied
physical aspects of the
historic environment.
Establish the scale of the
problem at a GB level.
Establish research sites to
monitor change and impacts.
Evaluate tree species offering
the most ecological and
cultural acceptance as future
veteran trees.
Examine rates of change at
research sites. Evaluate
social acceptance of heritage
loss and changing aesthetics
Education/behavioural
Increase awareness of
climate change issues within
Educate public on potential
impacts of climate change on
Assess public attitudes to
potential loss or changes to
CSG 15 (1/00)
25
Watching brief
Monitor changes and review
effectiveness
heritage organisations.
Improve guidance on water
management in woodland
environments.
the historic environment and
implications for loss and
aesthetics
some heritage features or
increased management costs.
Soils in mineral extraction, construction and the built environment
Table 14. Adaptation opportunities for climate change impacts on minerals and the building
environment
Adaptation type
Urgent
Long term
Watching brief
Share loss
Restrict revegetation plans to
those which are sustainable
after climate change testing
Bear loss
Invest in more rigorous
standards of reclamation
Prevent effects: structural and
technological
In depth review and updated
guidance for engineers
involved in greenspace
construction
Changing remediation and
reclamation practice
Monitor changes in practice
and review effectiveness
Prevent effects: legislative,
regulatory, institutional
Review conflicting policies
(e.g. biodiversity); review
land-use planning in context
of flood risk and prevention
Landscape scale planning in
brownfield redevelopment
and mineral extraction
Monitor changes and review
against actual changes in
climate and societal
expectations
Avoid or exploit changes in risk –
change location or other avoidance
strategy
Reconsider criteria for
choosing appropriate landuse following reclamation of
mineral sites
Research
Research on effects of
climate change on pollutant
pathways and mitigation
strategies;
Evaluation of social attitudes
to impacts of climate change
scenarios in urban areas
Evaluate trends in land-use
and greenspace sustainability
on reclaimed mineral and
brownfield sites
Education/behavioural
Publish current information
on effects of trees and tree
roots in the urban landscape
(ODPM); improve guidance
to landscape architects on
probable limitations to
vegetation
Educate public on probable
effects of climate change in
the city, and
political/economic choices
Monitor public (especially
urban dwellers) attitudes to
environmental issues
In context of mineral development, predicted changes to the soil are largely programmable and the industry should be able to adapt,
provided that information is released, and consequent changes needed in reclamation practice are enforced. The most important issue
today is to make sensible soil/soil-forming material provision for sites where vegetation longevity is measured in decades. Probable
effects of climate change on choice of vegetation and land-use must be published and publicized, and possible effects on policy
explored. In addition, the changing nature of rainfall events should be factored into surface water engineering on medium and large
mineral sites. Further guidance for the minerals industry may be warranted.
The ability of soils to hold and buffer contaminants and pollutants, particularly ‘brownfield’ soils may be affected by increases in
temperature and changing rainfall patterns. Although research is ongoing in this area, additional research input may be required to
make robust predictions across the range of soils that may be affected.
In the urban, built environment, little has been done to study the effects of climate change on pollutant linkage, either through
enhanced movement in contaminated substrates, or through flooding. Other important needs include the development of tools to
predict likely effects of climate change on greenspace engineering, and sensible choice of vegetation and land-use for sites and
materials available. There may be a need to develop further soil manufacture methodologies based on remediated and organic waste
materials, given an increasing reliance on plant available water stored in the profile to support vegetation during the growing season.
Again, further guidance to the reclamation, remediation and landscape industries seems warranted.
10 Collate and identify the ways forward and those preferred by
stakeholders
Recommendations
Research
CSG 15 (1/00)
26
1.
More research specifically aimed at soil functions under climate change is recommended. Climate impacts research not
directly focused on soils should incorporate, wherever possible, a consideration of possible soil impacts. Existing research
using the UKCIP98 scenarios should be updated using UKCIP02 – or at the very least, an assessment of possible changes to
research conclusions should be undertaken.
2.
Further investigation of the interactions between climate change and pollutant deposition and exposure, particularly critical
loads and their exceedance for agricultural land and woodland in relation to issues of acidification/recovery and
eutrophication.
3.
Future research into soil functions under climate change should attempt to deal with uncertainties in climate predictions and
soil process model formulation and parameterisation of soil processes. Model development for organic and woodland soils
needs to be promoted, including the collection of data required for parameterisation and verification.
4.
Studies integrating the impact of land use changes and socio-economic factors should be encouraged since these may be as
important as the impacts of climate change on soil functions.
5.
Further targeted research is recommended to investigate the effects of CO2 combined with changes in the temperature
regime on soil function, directly or indirectly, and interactions with changes in temperature and rainfall.
6.
More research is warranted on the ability of soils to hold and buffer pollutants in the face of climate change, particularly on
“brownfield” soils as well as in the urban, built environment.
7.
Improved estimates of non-CO2 GHG balance (primarily N2O and CH4) of forest soils, including predictions of the impacts
of climate change and the effects of forest management; extension to broadleaf woodland and deforestation activities is
important.
Monitoring
8.
Long-term site-specific monitoring studies (for example long-term experiments, ECN, Level I, Level II Long term
monitoring of forest ecosystems) as well as information from National Inventories and soil surveys should be used, where
relevant, for benchmarking and guiding new monitoring work to assess climate impacts on soil functions.
9.
Inventories of carbon stocks and stock changes should be enhanced with a focus on particularly vulnerable soils, including an
assessment of the effects of forest management.
Education
10.
There should be an extension of education initiatives to increase awareness of the impact of climate change on soils as it
affects, for instance, water resources, pollution and erosion.
Integration
11.
Better integration between research projects both within and between research funding bodies is recommended to achieve
considerable added value for relatively little effort
12.
Research into developing and applying integrated, holistic modelling assessment tools considering soil, climate, vegetation
and water interactions should be supported to allow a scientifically robust assessment of climate impacts on soil functions.
13.
Research investigating and integrating the use of currently available soil process models (for example, pesticide fate, water
relations, nutrient cycling and GHG fluxes) for climate impacts studies should be encouraged.
14.
The collation of information on the likely effects of climate change on soil chemical and physical properties and how
archaeological remains may be affected.
15.
The collation and integration of existing datasets and modelling tools relevant to the principal soil processes. This is an
essential step in developing Decision Support Systems for climate change risk management, with the objective of
implementing adaptation measures to maintain soil sustainability.
Next stage
16.
It is suggested that a Stakeholder meeting should be held to allow discussion of the review and to identify priorities for the
development of tools to mitigate and adapt to the impact of climate change on soils.
References
De Groot R., Wilson, M.A. and Boumans R.M.J., 2002, A typology for the classification, description and valuation of ecosystem
functions, goods, and services, Ecological Economics 41, 393-408.
Hulme M., Jenkins G.J., Lu X., Turnpeny J.R., Mitchell T.D., Jones R.G., Lowe J., Murphy J.M., Hassell D., Boorman P., McDonald
R., & Hill S. (2002) Climate change scenarios for the United Kingdom: The UKCIP02 scientific report. Tyndall Centre for
Climate Change Research, School of Environmental Science, University of East Anglia, Norwich. 120pp.
IPCC (2001) Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the
Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK
Acknowledgements
Project team
Ian Bradley
Andy Moffat
Elena Vanguelova
Pete Falloon
Jim Harris
Colleagues in NSRI: John Hollis, Ian Holman, Jack Hannam, Mark Freeman
Colleagues in Forest Research: Mark Broadmeadow, Peter Crow, Tony Hutchings
UKCIP: Chris West, Richenda Connell
CSG 15 (1/00)
27
Participants at Stakeholder Workshop
Respondents to informal questionnaire and discussions
CSG 15 (1/00)
28