Download Global warming and climate change

Global Warming and Climate Change in the UK
Abstract
There is a growing body of evidence to support the idea of global warming. Its impact on
the UK is varied and wide-ranging. To what extent changes in climate can be managed
is debatable, although the consequence of such change is profound.
Introduction
Recent data suggests that 2002 was the second warmest year on record. According to
The State Of The Climate – a report by the US National Oceanographic and
Atmospheric Administration (NOAA) – global temperatures have risen by 0.6ºC since
1900, although some regions such as Antarctica experienced significant cooling. Of this
warming, approximately 0.4°C has occurred in the last 30 years. 1998 was the warmest
year on record, with 2001 being the third warmest. The 1990s were the warmest decade
in the last 100 years, and it is likely that the last 100 years represented the warmest
century in the last millennium. Figure 1 shows the temperature variation around the
average temperature over the last 150 years and how it has consistently become
warmer than the average.
Figure 1 The average global surface-air temperature anomalies are shown in relation to
1961-1990 average
Evidence for the changes in global climate:
 an increase in minimum night-time temperatures over land
 an increase in the length of the frost-free season in many mid-to-high latitude
areas in the Northern Hemisphere
 more intense rainfall events over many Northern Hemisphere mid-to-high latitude
land areas
 a decrease in mountain glacier extent and ice masses across much of the world
 a decrease in sea-ice amounts and a substantial thinning of Arctic sea-ice in late
summer.
The debate continues between scientists about what is responsible for rising global
temperatures. Some believe that the Sun is causing the changes. The Sun periodically
brightens and fades, altering global temperatures. Presently, the Sun is brightening,
causing the Earth’s temperature to rise. A recent study suggests that the Sun may have
caused a temperature increase of 0.3ºC since 1980, accounting for 25 per cent of the
recorded increase since 1900. Other scientists believe that rising global temperatures
are caused by human activity, resulting in an enhanced greenhouse effect.
Figure 2 Global warming and climate change
Global warming and climate change
The greenhouse effect is the process by which certain gases (water vapour, carbon
dioxide, methane and chlorofluorocarbons (CFCs)) allow short-wave radiation from the
sun to pass through and heat up the earth, but trap an increasing proportion of out-going
long-wave radiation from the earth. This radiation leads to a warming of the atmosphere.
The enhanced greenhouse effect is the increasing amount of greenhouses gases in
the atmosphere as a result of human activities, and their impact on atmospheric
systems, including global warming.
One concern about global warming is the build-up of greenhouse gases. Carbon
dioxide (CO2) levels have risen from about 315ppm in 1950 to 355ppm and are expected
to reach 600ppm by 2050. The increase is due to human activities - burning fossil fuel
(coal, oil and natural gas) and deforestation. Deforestation of the tropical rain forest is a
double blow - not only does it increase atmospheric CO2 levels, it removes the trees that
convert CO2 into oxygen. When emissions of carbon dioxide are reduced, the rise of
average global temperatures is lowered as well as the rate and impacts of climate
change. Once released into the atmosphere, carbon dioxide remains there for about 100
years. So even if emissions are reduced, there will be a certain amount of warming
owing to greenhouse gases currently in the atmosphere. Emissions may have to be
reduced by as much as by 60 to 70 per cent to stabilise the climate completely.
Methane is the second largest contributor to global warming, and is increasing at a rate
of 1 per cent per annum. It is estimated that cattle convert up to 10 per cent of the food
they eat into methane, and each emit 100 million tonnes of methane into the
atmosphere. Natural wetland and paddy fields are another important source - paddy
fields emit up to 150 million tonnes of methane annually. As global warming increases,
bogs trapped in permafrost will melt and release vast quantities of methane.
Chlorofluorocarbons (CFCs) are synthetic chemicals that destroy ozone, as well as
absorb long-wave radiation. CFCs are increasing at a rate of 6 per cent per annum, and
are up to 10,000 times more efficient at trapping heat than CO2.
End
Causes of global climate change
The observed changes in global climate are the result of both natural and human
causes. The Earth's climate varies naturally as a result of a number of factors such as:
 fluctuations in energy received from the Sun (insolation)
 interactions between the ocean and the atmosphere
 changes in the Earth's orbit
 volcanic eruptions.
The main human influence on global climate is likely to be through increasing emissions
of greenhouse gases.
At present about 6.5 billion tonnes of carbon is emitted globally into the atmosphere
each year, mostly through the combustion of coal, oil and gas for energy. Changes in
land use result in a further 1-2 billion tonnes of carbon. However, pollutants from other
human activities can also play a part. For example, sulphur dioxide, which transforms
into small particles via the use of aerosols, can cool the climate. Figure 3 considers both
natural and human causes of climate change.
Figure 3 Natural and human causes are factored into the results shown on the graph.
Temperature change is shown in relation to the 1880-1920 average.
Computer simulations have shown that the changes in global climate can only be
properly modelled when human factors as well as natural ones are taken into account.
The Intergovernmental Panel on Climate Change (IPCC) was set up by the World
Meteorological Organization and the United Nations Environment Programme in 1988 to
assess scientific and socio-economic information on climate change and its impacts. In
its third Assessment Report it projects that global temperatures could rise by between
1.4 and 5.8°C by 2100.
The range of temperatures reflects a number of uncertainties. Many aspects of the
weather are not fully understood, such as the impact of clouds, the role of ocean
currents, and role of the carbon cycle in oceans and forests.
In 1995, the IPCC concluded that the balance of evidence suggested that the recent
observed warming of the Earth’s atmosphere was due to human activities.
The report, Global Atmosphere Research Programme 2000-2002, published by the
Department for Environment, Food and Rural Affairs (Defra) suggests that:
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atmospheric concentrations of many greenhouse gases reached their highestever levels in 2001
the three hottest years on record were 1998, 2001 and 2002
positive carbon cycle feedbacks from forests and vegetation could sharply speed
up future warming. (A positive feedback occurs when warming sets off a further
warming trend - when thawing permafrost, for example, releases a greenhouse
gas)
action being taken in the UK could reduce its total greenhouse gas emissions to
23 per cent below 1990 levels by 2010.
Impacts on the UK
A number of trends can be described in the UK’s changing climate:
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the growing season for plants in central England has increased by about one
month since 1900
heatwaves have become more frequent in summer
there are now fewer frosts and winter cold spells
winters over the last 200 years have become much wetter relative to summers
heavy rainfalls are more common than they were 50 years ago
average sea level around the UK is now about 10cm higher than it was in 1900.
Figure 4 The length of the growing season in central England. Deviations are in relation
to 1960-1990 average
Temperature
Central England has one of the longest temperature records, dating back to 1659.
Temperatures have increased by 0.7°C in the UK since 1659. Of that, a rise of 0.5°C
occurred in the 20th Century. Globally, average temperatures have increased by 0.6°C
since 1860. Note only has the land been warmed but so too have the seas around
Britain. The 1990s was the warmest decade in central England since records began.
Figure 5 The warming of central England climate (red) and surrounding UK coastal
waters (blue). Deviations are in relation to 1961-1990 average (note different scales)
Thermohaline circulation (THC)
Research at the Met Office shows that global warming could reduce the strength of the
thermohaline (THC) circulation by 25 per cent by 2100. However, the direct heating of
global warming would be greater than any cooling effect from reduced activity of the
THC. A cold future is therefore very unlikely.
Rainfall patterns
There have been a number of changes in precipitation patterns:
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winters have become wetter and stormier
summers have become drier
there are marked differences between the south and east, which has become
drier, and the north and west which have become wetter
autumn and winter flooding has become more common, as typified by the floods
of 2000-01 and 2002-03 (Figures 5 and 6)
Rising sea levels
Oceans absorb heat from the atmosphere. As the atmosphere warms, so too do the
oceans. When water is warmed, it expands (this is known as the steric effect), causing
sea levels to rise. In addition, as the temperature of the oceans and atmosphere
increases, glaciers and small ice sheets melt, releasing water into the oceans and
contributing to sea level rise.
In addition, the UK and northern Europe are still responding to the melting of ice sheets
that covered the land during the last Ice Age. Mainland Britain is slowly tilting, with South
and East England slowly sinking into the sea and the North West and Scotland rising.
Sea levels are on average 10cm higher than they were in 1900.
Future changes - climate change scenarios for the UK
In 2002 the Department for Environment, Food & Rural Affairs (Defra) published the
UKCIP02 scenarios, which present four different descriptions of how the world may
develop in the decades to come. They are based on four different emission scenarios
from the IPCC. The scenarios provide alternative views of the future, depending on
choices made by society.
The four scenarios are described by the emission scenarios on which they are based:
Low Emissions, Medium-Low Emissions, Medium-High Emissions and High Emissions.
According to these scenarios the UK will change in the following ways.
Temperature
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The UK climate will become warmer
By the 2080s, the average annual temperature in the UK may rise by between
2°C for the Low Emissions scenario and 3.5°C for the High Emissions scenario.
There will be greater warming in the south and east rather than in the north and
west, and there may be greater warming in summer and autumn than in winter
and spring. The temperature of UK coastal waters will also increase, although not
as rapidly as over land.
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High summer temperatures will become more frequent, whilst very cold winters
will become increasingly rare
A very hot August, such as experienced in 1995 when temperatures over
England and Wales averaged 3.4°C 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.
Figure 6 How will temperature changes affect the UK?
If there is an increase of temperature of If temperatures increase 1.5ºC the
0.5ºC the following are expected to occur:
following may happen:
 2-3% increases in the summer and winter
precipitation in the northwest
 2-3% decreases summer precipitation in the
southeast
 5% decrease in annual runoff in the south
 frequency of drought conditions increases
from 1:90 to 1:25
 disappearance of niche species e.g. alpine
wood fern and oak fern
 in-migration of some continental species
and expansion of some species e.g. Red
Admiral and Painted Lady butterflies
 3% increase in timber activity
 21% increase in demand for irrigated water
over the increase without climate change, and
2% increase in domestic demand
 6% decrease in heating demands
 7% increase in summer and winter
precipitation in the northwest and 7-8%
decrease in summer precipitation in the
southeast
 15% decrease in annual runoff in the
south
 frequency of drought conditions
increases from 1:90 to 1:3
 further disappearance of several
species
 further in-migration of several species
 15% increase in timber productivity
 63% increase in demand for irrigated
water over the increase without climate
change, and 7% increase in domestic
demand
 16% decrease in heating demands
Precipitation
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Winters will become wetter and summers may become drier throughout the UK
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 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 will become more frequent
By the 2080s, heavy winter precipitation intensities that are currently experienced
around once every two years may become between 5 (Low Emissions) and 20%
(High Emissions) heavier.
Sea level changes
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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 2cm below
(Low Emissions) and 58cm above (High Emissions) the current level in western
Scotland, but between 26cm and 86cm above the current level in southeast England
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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 than they do now, under the Medium-High
Emissions scenario.
Figure 7 – Major industrial areas – such as Liverpool and the Mersey are at risk from
rising sea levels
Figure 8 – Low lying areas such as salt marshes, will be increasingly vulnerable to
increased storm frequency and intensity resulting from global warming (Newtown, Isle of
Wight)
Environments at risk
The changes in plant communities, species, migrations, losses and gains will in time
change many of the landscapes with which we are familiar as follows:
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Montane/alpine and northern/arctic plant and animal species, which have nowhere to
go if it becomes warmer. Good examples are the tufted saxifrage and alpine woodsia
fern. Animal species include the mountain hare, ptarmigan, snow bunting and white
fish
Species confined to particular locations from which they cannot readily escape
because, for instance, they occupy cold, damp refuges, isolated habitats or are
dependent on particular other species for pollination, food or to complete their life
cycle
heaths may become subject to more frequent fires as southern Britain becomes
warmer and experiences dry summers such as those in 1990 and 1995
wetlands may dry out more frequently with the change in species composition,
especially if current water obstruction from aquifers were increased
coastal dunes and rocks may be invaded more rapidly by alien species such as the
hottentog fig
species of salt marshes and soft coastal communities that cannot retreat landward in
the face of sea level rise
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some broad-leafed woodland and dry areas of Britain may decline further in
response to increased frequency of summer droughts, particularly in the south where
summer droughts are forecast to be more frequent and severe.
The main types of potential health impact of climatic change
Direct impacts
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Death, illness and injury due to increased exposure to heatwaves.
Reduction in cold-related diseases/disorders.
Altered rates of death, illness and injury due to changes in frequency or intensity
of climate-related disasters (droughts, floods, forest fires etc).
Indirect impacts
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Altered distribution and transmission of vector borne infectious diseases (viral
infections, malaria, leishmaniasis).
Altered distribution and transmission of certain communicable diseases (water borne
and food borne infections, some respiratory infections).
Impacts upon agriculture and other food production – adverse effects are most likely
in tropical and sub-tropical regions; beneficial effects may occur in some temperate
zones.
The effects upon respiratory systems via increased exposure to pollens, spores and
certain air pollutants.
Consequences of sea level rise via flooding, disrupted sanitation, soil and water
salination and altered breeding sites for infectious disease vectors.
Impacts on health caused by demographic disruption, displacement and a decline in
socio-economic circumstances as might result from impacts of climatic change on
natural and managed ecosystems.
The likely effects of a changing climate in the UK
Positive effects
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An increase in timber yields (up to 25 per cent by 2050s) especially the north of the
UK (with perhaps some decrease in the south).
A northward shift of farming zones by about 200-300km per degree centigrade of
warming, or 50-80km per decade. This will improve some forms of agriculture
especially pastoral farming in the northwestern part of the UK.
Enhanced potential for tourism and recreation as a result of increased temperatures
and reduced precipitation in the summer, especially in the south.
Negative effects
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An increase in the soil dryness, soil erosion and the shrinkage of clay soils.
Figure 10 – Farmoor reservoir at ‘normal’ summer capacity
Figure 11 – Farmoor reservoir at 60% of ‘normal’ summer capacity in 2003
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An increase in animal, especially insect, species as a result of northward migration
from the Continent and a small decrease in the number of plant species due to the
loss of northern and montane (mountain types).
A decrease in crop yields in the southeast.
An increase in river flow in the winter and a decrease in the summer, especially in
the south.
An increase in public and agricultural demand for water.
Increased storm damage due to the rise in the frequency of storms, flooding and
erosion on natural and human resources and human resource assets in coastal
areas.
Figure 12 – As a result of increased storm frequency, mass movement and cliff
vulnerability are likely to increase (Barton cliffs, Hampshire)
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Increased incidents of certain infectious diseases in humans and an increase in the
health effects of episodes of extreme temperature.
Possible solutions
Emissions of the main anthropogenic greenhouse gas, CO2, are influenced by:
 the size of the human population
 the amount of energy used per person
 the level of emissions resulting from that use of energy.
Reducing the greenhouse effect
Although greenhouse gases are at the highest levels ever recorded, there are a variety
of technical options that could reduce emissions. Reducing CO2 emissions can be
achieved through:
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improved energy efficiency
fuel switching
use of renewable energy sources
nuclear power
capture and storage of CO2.
Another measure involves increasing the rate at which natural sinks take up CO 2 from
the atmosphere, for example by increasing the amount of forests.
For other greenhouse gases:
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reduce agricultural use of nitrogen fertilisers
expand methane extraction from waste tips
reduce process emissions of fluorocarbons from aluminium smelters, and ban their
use of chemicals to reduce use of hydrofluorocarbons.
For the energy sector:
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introduce a carbon tax on electricity generation
introduce a higher carbon dioxide tax and retain the existing energy tax on nonenergy-intensive industry
introduce an energy tax on combined heat and power
introduce measures to save electricity (including standards for domestic appliances).
For the transport sector:
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new rules on company cars and tax (to reduce long-distance travel)
expand public transport systems
set carbon dioxide emission limits on light vehicles
further develop environmental classification systems for vehicles and fuels
reduce average speeds on roads
subject all transport plans and infrastructure investments to environmental impact
assessments
experiment with the introduction of electric vehicles.
International policy to protect climate
The Toronto conference of 1998 called for the reduction of CO2 emissions by 20 per cent
of the 1998 levels by 2005. Also in 1988 the Intergovernmental Panel on Climate
Change (IPCC) was established by UNEP and the World Meteorological Organization.
The UN Conference on the Environment and Development (UNCED) was held in 1992
in Rio de Janeiro. It covered a range of subjects and there were a number of statements
including the Framework Convention on Climate Change (FCCC). This came into force
in March 1994. ‘The ultimate objective (of the convention)… is to “achieve… stabilisation
of greenhouse gas concentrations in the atmosphere at a level that would prevent
dangerous anthropogenic interference with the climate system”.
The Kyoto Protocol (1997) was an addition to the Rio Convention. It gave all MEDCs
legally binding targets for cuts in emissions from the 1990 level by 2008-12. The EU
agreed to cut emissions by 8 per cent, Japan by 7 per cent, and the USA by 6 per cent.
Some countries found it easier to make cuts than others. The UK exceeded its
international target for cutting greenhouse emissions by 2000 and is on track to exceed
its Kyoto Protocol target of a 12.5 per cent cut in emissions below 1990 levels by 200812.
There are three main ways for countries to keep to the Kyoto target without cutting
domestic emissions:
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plant forests to absorb carbon or change agricultural practices e.g. keeping fewer
cattle
install clean technology in other countries and claim carbon credited for themselves
buy carbon credits from countries such as Russia where traditional heavy industries
have declined and the national carbon limits are underused.
Even if greenhouse gas production is cut by between 60 and 80 per cent there is still
enough greenhouse gas in the atmosphere to raise temperatures by 5ºC. Stabilising the
amount of atmospheric CO2 will be hard, because a warming world will trigger feedback
mechanisms. The Kyoto agreement was only meant to be the beginning of a long-term
process, not the end of one.
However, the guidelines for measuring and cutting greenhouse gases were not finished
in Kyoto. For example, it was not decided to what extent the planting of forests and
carbon trading could be relied upon. Since George W Bush was elected President of the
USA he has rejected the Kyoto Protocol since it would hurt the US economy and
employment.
Although the rest of the world could proceed without the USA, the USA emits about 25
per cent of the world’s greenhouse gases. So without the USA, and LEDCs such as
China and India, the reduction of carbon emission would be seriously hampered.
According to the Kyoto rules 55 countries must ratify the agreement to make it legally
binding worldwide, and 55 per cent of the emissions must come from MEDCs. If the EU,
Eastern Europe, Japan and Russia agree, they could just make up 55 per cent of the
MEDCs’ emissions. Without the USA (and Australia and Canada who are against cutting
emissions) it is difficult to achieve this goal.
Conclusion
Climate change appears to be accelerating. Much of it is natural, but increasingly more
of it is due to human activities. In the UK climate change will have a major impact on
water resources, flora, fauna, soils, agriculture, tourism and even human health.
There have been many attempts to tackle climate change. These date from the 1970s
but to date there has been little success. This is partly because countries feel there is
too much to lose. Achieving international agreement over climate is likely to prove very
difficult.
Further references
http://www.defra.gov.uk/environment/climatechange/research/report02/
The Global Atmospheric Research Programme Report 2000-02 summarises the main
research findings of the Global Atmosphere Division Research Programme and how
these have been used to support the development of policy with regard to human
induced ozone depletion and climate change.
http://www.meto.gov.uk/research/hadleycentre/
Hadley Centre for Climate Prediction and Research provides a wide variety of articles
and maps on future climates of the UK.
http://www.ukcip.org.uk/
UK Climate Impacts Programme has an excellent set of regional maps showing potential
scenarios for climate change in the UK.
Briefing report
Hulme, M., Turnpenny, J., Jenkins, G., (2002)
Climate Change Scenarios for the United Kingdom: The UKCIP02 Briefing Report.
Tyndall Centre for Climate Change Research, School of Environmental Sciences,
University of East Anglia, Norwich, UK. 14pp
Briefing Report pages 1-7
Briefing Report pages 8-14