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CLIMATE CHANGE AND ECOSYSTEMS MODIFICATION
Professor A.M.A Imevbore, FAS
Office Address :
Environmental Resources Managers Ltd.
107A Imam Abibu Adetoro Street,
Victoria Island, Lagos.
E-mail: [email protected]
Home Address :
9A, Oladipo Olawande Street,
Parakin – Obalufe Layout,
Ile-Ife, Osun State.
paper presented at the
2nd Joint International Conference organized by the University of Ilorin, Nigeria and University of Cape Coast, Ghana, at the University Auditorium, Ilorin, 1st – 5th
May, 2011.
OUTLINE
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Introduction
Greenhouse gases warm the planet
Climate change – worldwide impacts
What is an ecosystem?
How do ecosystems function?
What do ecosystems deliver?
How do ecosystems interact with climate?
How does climate modify ecosystem functions and
services?
Ecosystem-based Approaches for Adaptation to climate
change
Barriers and responses to sustainable ecosystem management
Acknowledgements
References
INTRODUCTION
There is a growing concern about climate change and the impact it has on people and the ecosystems on
which they depend. Temperatures have already risen 1.4°F since the start of the 20th century – with much of
this warming occurring in just the last 30 years. It is also predicted that temperatures will likely rise at least
another 2°F, and possibly more than 11°F, over the next 100 years (The National Academies, 2008).
According to the Intergovernmental Panel on Climate Change (IPCC, 1990), “natural terrestrial ecosystems
could face significant consequences as a result of the global increases in the atmospheric concentrations of
greenhouse gases and the associated climatic changes. Projected changes in temperature and precipitation
suggest that climatic zones could shift several hundred kilometres towards the poles over the next fifty years.
Flora and fauna would lag behind these climatic shifts, surviving in their present location and, therefore, could
find themselves in a different climatic regime. These regimes may be more or less hospitable and, therefore,
could increase productivity for some species and decrease that of others. Ecosystems are not expected to
move as a single unit, but would have a new structure as a consequence of alterations in distribution and
abundance of species.”
The rate of projected climate changes is the major factor determining the type and degree of climatic impacts
on natural terrestrial ecosystems. These rates are also likely to be faster than the ability of some species to
respond. Some species could be lost owing to increased stress leading to a reduction in global biological
diversity. Increased incidence of disturbances such as pest outbreaks and fire are likely to occur in some areas
and these could enhance projected ecosystem changes.
The socioeconomic consequences of these impacts will be significant, especially for those regions of the globe
where societies and related economies are dependent on natural ecosystems for their welfare. Changes in the
availability of food, fuel, medicine, construction materials and income are possible as these ecosystems are
changed
In aquatic systems, relatively small climate changes can cause large water resource problems in many areas,
especially in arid and semi-arid regions and in those humid areas where demand or pollution has led to water
scarcity. On the whole, it appears that in many areas, climate change will cause increase precipitation, soil
moisture and water storage, thus altering patterns of agriculture, and other water uses. Water availability may
also decrease in other areas, a most important factor for already marginal situations, in areas such as the
Sahelian zone in Africa.
These changes are likely to affect the most vulnerable human settlements such as those exposed to natural hazards, e.g.
coastal or river flooding, severe drought, landslides, severe wind storms and tropical cyclones. Unfortunately, such
settlements are most abundant among the lower income groups of developing countries. Among such groups, major
health impacts are possible, especially in large urban areas, owing to changes in availability of water and food and
increased health problems due to heat stress spreading of infections. Changes in precipitation and temperature could
also radically alter the patterns of vector-borne and viral diseases by shifting them to higher latitudes, thus putting large
populations at risk. Similar events have in the past led to large migrations of people, leading over a number of years to
severe disruptions of settlement patterns and social instability in some areas (IPCC, 1990).
GREENHOUSE GASES WARM THE PLANET
Most scientists agree that the warming in recent decades has been caused primarily by human activities that have
increased the amount of greenhouse gases in the atmosphere.
Appendix I provides a list of the greenhouse gases that warm the planet.
 These gases have increased significantly since the Industrial Revolution, mostly from the burning of fossil fuels for
energy, industrial processes, and transportation. Carbon dioxide levels are at their highest in at least 650,000 years and
they continue to rise.
Their effects have increased ocean temperatures causing thermal expansion of the oceans and in combination with
meltwater from land-based ice are also causing sea level rise.
Sea levels rose during the 20th century by 0.17 metres. By 2100, sea level is expected to rise between 0.18
and 0.59 metres.
However, there are uncertainties in this estimate mostly due to uncertainty about how much water will be
lost from ice sheets (Bindoff et al., 2007). For example Greenland is showing rising loss of mass in recent years
(UNEP, 2007). Increased melting of sea ice and freshwater influx from melting glaciers and ice sheets also has
the potential to influence global patterns of ocean circulation.
As a result of global warming, the type, frequency and intensity of extreme events, such as tropical cyclones
(including hurricanes and typhoons), floods, droughts and heavy precipitation events, are expected to rise
even with relatively small average temperature increases. Changes in some types of extreme events have
already been observed, for example, increases in the frequency and intensity of heat waves and heavy
precipitation events (Meehl et al., 2007).
Climate change will have wide-ranging effects on the environment, and on socio-economic and related
sectors, including water resources, agriculture and food security, human health, terrestrial ecosystems and
biodiversity and coastal zones.
Changes in rainfall pattern are likely to lead to severe water shortages and/or flooding. Melting of glaciers
can cause flooding and soil erosion.
Rising temperatures will cause shifts in crop growing seasons which affects food security and changes in the
distribution of disease vectors putting more people at risk from diseases such as malaria and dengue fever.
 Temperature increases will potentially severely increase rates of extinction for many habitats and
species (up to 30 per cent with a 2° C rise in temperature). Particularly affected will be coral reefs,
boreal forests, Mediterranean and mountain habitats. Increasing sea levels also mean greater risk of
storm surge, inundation and wave damage to coastlines, particularly in small island States and
countries with low lying deltas. A rise in extreme events will have effects on health and lives as well as
associated environmental and economic impacts.
 There is no doubt that climate will continue to change throughout the 21st century and beyond, but
there are still important questions regarding how large and how fast these changes will be, and what
effects they will have in different regions.
 In some parts of the world, global warming could bring positive effects such as longer growing
seasons and milder winters. In other areas, it is likely to bring harmful effects to a much higher
percentage of the world’s people. For example, people in coastal communities will likely experience
increased flooding due to rising sea levels.
CLIMATE CHANGE – WORLDWIDE IMPACTS
Scientists from around the world with the IPCC tell us that during the past 100 years, the world's surface air
temperature increased at an average of 0.6° Celsius (1.1°F). This may not sound like very much change, but
even one degree can affect the Earth.
Appendix II provides some effects of climate change that we see happening worldwide.
Climate change is thus affecting nature’s ecosystems and the habitats that support life – from oceans to
grasslands to forests. Changes are expected to alter the makeup and functioning of ecosystems, as well as
some of the critical benefits that ecosystems provide to people. Climate change can also threaten ecosystems
that have already been weakened by other human activities such as pollution, development, and
overharvesting.
Changes in the climate also impact biological diversity and thereby an ecosystem’s ability to deliver goods and
services for human well-being. Moreover, ecosystem services play a central role in both adaptation to and
mitigation of climate change. Sustaining biological diversity and ecosystem services are hence important both
in our efforts to deal with climate change and to reach the UN’s Millennium Development Goals.
Biodiversity: Climate change can have broad effects on biodiversity (the number and variety of plant and animal species
in a particular location). Although species have adapted to environmental change for millions of years, a quickly
changing climate could require adaptation on larger and faster scales than in the past. Those species that cannot adapt
are at risk of extinction. Even the loss of single specie can have cascading effects because organisms are connected
through food webs and other interactions.
Freshwater ecosystems: According to the World Bank (2010), under current climate projections, most fresh water
ecosystems will face ecologically significant climate change impacts by the middle of this century. Although, not all
freshwater ecosystems will be affected in the same way by climate change, the impacts of climate change on freshwater
ecosystems will be complex and hard to predict. These impacts will lead to changes in the quantity, quality, and timing of
water.
Oceans: The oceans and the atmosphere are constantly interacting—exchanging heat, water, gases, and particles. As the
atmosphere warms, the ocean absorbs some of this heat. The amount of heat stored by the ocean affects the
temperature of the ocean both at the surface and at great depths. Warming of the Earth’s oceans can affect and change
the habitat and food supplies for many kinds of marine life—from plankton to polar bears.
The oceans also absorb carbon dioxide from the atmosphere. Once it dissolves in the ocean, carbon dioxide reacts with
sea water to form carbonic acid. As people put more carbon dioxide into the atmosphere, the oceans absorb some of
this extra carbon dioxide, which leads to more carbonic acid. An increasingly acidic ocean can have negative effects on
marine life, such as coral reefs.
Forests: Although some forests may derive near-term benefits from an extended growing season, climate change is also
expected to encourage wildfires by extending the length of the summer fire season. Longer periods of hot weather
could stress trees, and make them more susceptible to wildfires, insect damage, and disease. Climate change has likely
already increased the size and number of forest fires, insect outbreaks, and tree deaths, particularly in Africa.
West Africa’s climate: According to ECOWAS-SWAC/OECD (2008), rainfall patterns in West Africa are linked to the
seasonal movement of the inter-tropical convergence zone, where the hot and dry tropical easterly winds blowing in
from the northeast meet with the humid air masses coming in from the Southern Atlantic Ocean, linked to the onset of
the monsoon. The semi-arid zone, essentially including the Sahel and Sahel-Saharan belt, is marked by a single rainy
season. The Sahel receives most of its rainfall between July and September. Further south, the climate in the Gulf of
Guinea countries is marked by the alternation of two rainy seasons and two dry seasons.
There has been a substantial reduction in rainfall in West Africa over the last fifty years, with a clear break between 1968
and 1972. The reduction is extremely clear in the Sahel, with highly deficit periods in 1972-73, 1982-84 and 1997. This
trend has taken the form of a 200-kilometer downward slide in isohyets towards the South and a historic aridification
process in the area’s climate. The decrease in rainfall has not spared the Sudanese and Guinean areas either. The change
in rainfall pattern that has taken place in the previous decades may not necessarily settle. Since the mid-1990s, a return
to better rainfall conditions has been noted, in particular in continental Sahel.
WHAT IS AN ECOSYSTEM?
An ecosystem is an interdependent system of plants, animals, and microorganisms interacting with one
another and with their physical environment. Ecosystems provide people with food, goods, medicines, and
many other products. They also play a vital role in nutrient cycling, water purification, and climate moderation.
According to Ellis (2008), ecosystems are composed of organisms interacting with each other and with their
environment such that energy is exchanged and system-level processes, such as the cycling of elements,
emerge. The ecosystem is a core concept in Biology and Ecology, serving as the level of biological organization
in which organisms interact simultaneously with each other and with their environment. As such, ecosystems
are a level above that of the ecological community (organisms of different species interacting with each other)
but are at a level below, or equal to, biomes and the biosphere.
Ecosystems include living organisms, the dead organic matter produced by them, the abiotic environment
within which the organisms live and exchange elements (soils, water, atmosphere), and the interactions
between these components. Ecosystems embody the concept that living organisms continually interact with
each other and with the environment to produce complex systems with emergent properties, such that "the
whole is greater than the sum of its parts" and "everything is connected".
The spatial boundaries, component organisms and the matter and energy content and flux within ecosystems may be
defined and measured. However, unlike organisms or energy, ecosystems are inherently conceptual, in that different
observers may legitimately define their boundaries and components differently. For example, a single patch of trees
together with the soil, organisms and atmosphere interacting with them may define a forest ecosystem, yet the entirety
of all organisms, their environment, and their interactions across an entire forested region in the Amazon might also be
defined as a single forest ecosystem. Some have even called the interacting system of organisms that live within the guts
of most animals as an ecosystem, despite their residence within a single organism, which violates the levels of
organization definition of ecosystems. Moreover, interactions between ecosystem components are as much a part of the
definition of ecosystems as their constituent organisms, matter and energy. Despite the apparent contradictions that
result from the flexibility of the ecosystem concept, it is just this flexibility that has made it such a useful and enduring
concept.
HOW DO ECOSYSTEMS FUNCTION?
According to Mooney et al (2009), in a given locality, organisms interact with the physical environment, and each other,
as they compete for the building blocks for growth and reproduction, that is, water, nutrients and energy. These
interactions in turn result in the mining of minerals from depths into living structures and back again to the surface, the
movement of water from the soil through plants into the atmosphere, and the capture of carbon from the atmosphere,
enabling the assembly of complex molecules and structures, and its subsequent release to the atmosphere through
respiration and decomposition. These basic biogeochemical and growth processes represent the operation of an
ecosystem. But there is more, the interaction and competition of the collected organisms result in a myriad of
biochemical strategies for defense against predators as well as for structures and behaviors that promote the exchange
of genetic material such as in pollination, often using intermediary species or collection of species for this task.
On the other hand, human intervention is creating major new sources of carbon emissions from the use of fossil fuels
which degrade natural sinks of carbon and pollute or transform natural ecosystems. The result is that the earth is now
emitting more carbon to the atmosphere than it can absorb – leading to climate change.
WHAT DO ECOSYSTEMS DELIVER?
In its natural system, various processes and interactions in a functional ecosystem deliver services of benefit to society
such as food, clean water, erosion control and cultural values. On the other hand, human activities can either enhance or
destroy those interactions since they are major components of these systems.
Appendix III provides a list of ecosystem services and functions.
It is clear from the appendix that ecosystems services and goods cover a wide range of benefits to the human society.
HOW DO ECOSYSTEMS INTERACT WITH CLIMATE?
Even if there were no human activities on planet Earth, carbon would flow through the atmosphere because of natural
biological and geological activity. Planet Earth is a dynamic geological and biological system. It produces and absorbs
carbon and other greenhouse gases through a range of natural cycles and across a wide variety of ecosystems, which has
resulted in the past climate patterns.
Human activity has intervened in these natural carbon cycles in two main ways:
By creating major new sources of carbon emissions from the use of fossil fuels;
By degrading natural sinks of carbon through polluting or transforming natural ecosystems.
The combined result of these human interventions has been to change the planetary balance between the sources, sinks and storage pools of
carbon. Put crudely, Earth is now emitting more carbon to the atmosphere than it can absorb. This changing imbalance is reflected in a
progressive increase in CO2 concentrations in the atmosphere which has led to climate change.
Putting these things together, it can be seen that there are three main components to the global carbon cycle.
Those emissions due to human activity.
Those emissions from ecosystems.
There is only one sink: the capacity of global ecosystems to absorb carbon.
HOW DOES CLIMATE MODIFY ECOSYSTEM FUNCTIONS AND SERVICES?
Climate change modifies ecosystem interactions and functions drastically and may in certain circumstances put ecosystems, their functions and
services at severe risk. For example, ecosystems are likely to show poor recovery when affected by climatic stressors and natural disturbances if
they are in degraded state. This is because persistent stresses on ecosystems weaken their resilience making ecosystems more susceptible to
natural disturbances that otherwise could have been absorbed.
Climate change can degrade the quality of ecosystems: According to Parry et al. (2009), unprecedented global change disturbances are likely to
affect ecosystems that are already stressed by multiple non-climatic stressors undermining even further their capacity to respond and adapt.
Table I produced by the World Bank (2010) describes in further detail how key eco-hydrological impacts of climate change affect freshwater
ecosystems and species.
Table
I:
Key
Eco-hydrological
Impacts
of
Climate
Change
on
Freshwater
Ecosystems
and
Species.
Impacts of Climate Change

Eco-Hydrological
Impacts
Changes in volume and timing
of precipitation
Increased evapotranspiration
Shift from snow to rain, and/or
earlier snowpack melt
Reduced groundwater recharge
Increase in the variability and
timing of monsoon
Increased demand for water in
response to higher
temperatures and climate
mitigation responses
Shift from snow to rain, and/or
earlier snowpack melt
Changes in precipitation timing
Increase in the variability and
timing of annual monsoon
1.


Increased temperatures
Reduced precipitation and
runoff

Increased precipitation and
runoff
More intense rainfall events









Increased low-flow
episodes and water
stress
Impacts for Ecosystems and
Species




Shifts in timing of
floods and
freshwater pulses

3.
Increased
evaporative losses
from shallower water
bodies

4.
Higher and more
frequent storm flows
2.












Changes in air temperature and
seasonality
Changes in the ice breakup
dates of lakes
5.
Reduced precipitation and
runoff
Higher storm surges from
tropical storms
Sea-level rise
Increase in intensity and
frequency of extreme
precipitation events
6.
Changes in air temperature
Increased variability in
temperature
8.
7.
Shifts in the
seasonality and
frequency of thermal
stratification (i.e.,
normal seasonal
mixing of cold and
warm layers) in lakes
and wetlands

Saltwater
encroachment in
coastal, deltaic, and
low-lying
ecosystems
More intense runoff,
leading to increased
sediment and
pollution loads

Hot or coldwater
conditions and shifts
in concentration of
dissolved oxygen








Reduced habitat availability
Increased temperature and pollution
levels
Impacts on flow-dependent species
Impacts on estuarine ecosystems
Impacts on spawning and emergence
cues for critical behaviors
Impacts on key hydrology-based lifecycle stages (e.g., migration, wetland
and lake flooding)
Permanent water bodies become
temporary/ ephemeral, changing mix of
species (e.g., from fish-dominated to
fairy shrimp–dominated)
Floods remove riparian and bottomdwelling organisms
Changes in structure of available
habitat cause range shifts and wider
floodplains
Less shading from near-channel
vegetation leads to extreme shallow
water temperatures
Species requiring cold-water layers lose
habitat
Thermal refuges disappear
More frequent algal-dominated
eutrophic periods from disturbances of
sediment; warmer water
Species acclimated to historical
hydroperiod and stratification cycle are
disrupted, may need to shift ranges in
response
Increased mortality of saline-intolerant
species and ecosystems
Salinity levels will alter coastal habitats
for many species in estuaries and up to
100 km inland
Increase of algal-dominated eutrophic
periods during droughts
Raised physiological and genetic
threats from old industrial pollutants
such as dioxins
Direct physiological thermal stress on
species
More frequent eutrophic periods during
warm seasons
Climate change can cause changes in ecosystem composition and function and lead to increased vulnerability. If some
key functional species are not able to respond to climate change, the result could be large changes in ecosystem
composition and function and increased vulnerability of ecosystems to natural and anthropogenic disturbances. This
could result in further species diversity reductions (Malcolm et al. 2002) and possible collapse or change in the state of
ecosystems (e.g. 75% of the world’s Lesser flamingo breed in lake Natron, Northern Tanzania, derive nourishment from
the East Africa Rift Valley soda lakes, which are in fragile, semi-desert conditions. If rainfall were to fail, or rainfall were
excessive, their habitat would flood, and birds would neither feed nor breed).
In 2007, the United Nations Framework Convention on Climate Change (UNFCCC) secretariat produced a book titled
“Climate Change: Impacts, Vulnerabilities and Adaptation in Developing Countries,” to highlight the concerns and needs
of developing countries in adapting to the effects of climate change. The book outlines the impact of climate change in
four developing country regions: Africa, Asia, Latin America and small island developing States. It also describes the
vulnerability of these regions to future climate change; current adaptation plans, strategies and actions; and future
adaptation options and needs.
The document has made clear that Africa is already a continent under pressure from climate stresses and that the
continent is highly vulnerable to the impacts of climate change. Many areas in Africa were recognized as having climates
that are among the most variable in the world on seasonal and decadal time scales. Not only could floods and droughts
occur in the same area within months of each other, the events could lead to famine and widespread disruption of
socio-economic well-being.
Many factors contribute and compound the impacts of current climate variability in Africa and will have negative effects on the continent’s ability to
cope with climate change. These include:
 poverty,
 illiteracy and lack of skills,
 weak institutions,
 limited infrastructure,
 lack of technology and information,
 low levels of primary education and health care,
 poor access to resources,
 low management capabilities and armed conflicts.
The overexploitation of land resources including forests, increases in population, desertification and land degradation pose additional threats (UNDP,
2006). In the Sahara and Sahel, dust and sand storms have negative impacts on agriculture, infrastructure and health.
Table II highlights some impacts of climate change in Africa on key sectors and gives an indication of the adaptive capacity of this continent to climate
change. As a result of global warming, the climate in Africa is predicted to become more variable, and extreme weather events are expected to be more
frequent and severe, with increasing risk to health and life. This includes increasing risk of drought and flooding in new areas (Few et al., 2004,
Christensen et al., 2007) and inundation due to sea-level rise in the continent’s coastal areas (Nicholls, 2004; McMichael et al. 2004).
Table II: Regional Impacts and Vulnerabilities to Climate Change in Africa.
Impacts
Sectoral Vulnerabilities
Adaptive Capacity
Temperature
–
Higher warming (x1.5)
throughout the continent and
in all seasons compared with
global average.
–
Drier subtropical regions may
become warmer than the
moister tropics.
Water
–
Increasing water stress for many countries.
–
75–220 million people face more severe
water shortages by 2020.
Africa has a low adaptive capacity to
both climate variability and climate
change exacerbated by existing
developmental challenges including:
–
low GDP per capita
–
widespread, endemic poverty
–
weak institutions
–
low levels of education
–
low levels of primary health care
–
little consideration of women
and gender balance in policy
planning
–
limited access to capital,
including markets, infrastructure
and technology
–
ecosystems degradation
–
complex disasters
–
conflicts
Precipitation
–
Decrease in annual rainfall in
much of Mediterranean Africa
and the northern Sahara, with
a greater likelihood of
decreasing rainfall as the
Mediterranean coast is
approached.
–
Decrease in rainfall in
southern Africa in much of the
winter rainfall region and
western margins.
–
Increase in annual mean
rainfall in East Africa.
–
Increase in rainfall in the dry
Sahel may be counteracted
through evaporation.
Extreme Events

Increase
in
frequency
and
intensity
of
extreme
events,
including droughts and floods,
as well as events occurring in
new areas.
Agriculture and food security
–
Agricultural production severely
compromised due to loss of land, shorter
growing seasons, more uncertainty about
what and when to plant.
–
Worsening of food insecurity and increase
in the number of people at risk from hunger.
–
Yields from rain-fed crops could be halved
by 2020 in some countries. Net revenues
from crops could fall by 90% by 2100.
–
Already compromised fish stocks depleted
further by rising water temperatures.
Health
–
Alteration of spatial and temporal
transmission of disease vectors, including
malaria, dengue fever, meningitis, cholera,
etc.
Terrestrial Ecosystems
–
Drying and desertification in many areas
particularly the Sahel and Southern Africa.
–
Deforestation and forest fires.
–
Degradation of grasslands.
–
25–40% of animal species in national
parks in sub-Saharan Africa expected to
become endangered.
Coastal Zones
–
Threat of inundation along coasts in
eastern Africa and coastal deltas, such as
the Nile delta and in many major cities due
to sea level rise, coastal erosion and
extreme events.
–
Degradation of marine ecosystems
including coral reefs off the East African
coast.
–
Cost of adaptation to sea level rise could
amount to at least 5–10% GDP.
Source: Boko et al., 2007; Christensen et al., 2007
Africa will face increasing water scarcity and stress with a subsequent potential increase of water conflicts as almost all
of the 50 river basins in Africa are transboundary (Ashton 2002, De Wit and Jacek, 2006). Agricultural production relies
mainly on rainfall for irrigation and will be severely compromised in many African countries, particularly for subsistence
farmers and in sub-Saharan Africa. Under climate change much agricultural land will be lost, with shorter growing
seasons and lower yields.
There is also evidence that climate change will cause a general decline in most of the subsistence crops, e.g. sorghum in
Sudan, Ethiopia, Eritrea and Zambia; maize in Ghana; Millet in Sudan; and groundnuts in Gambia. Of the total additional
people at risk of hunger due to climate change, Africa may well account for the majority by the 2080s (Fischer et al.,
2002).
Africa is also vulnerable to a number of climate sensitive diseases including malaria, tuberculosis and diarrhea (Guernier
et al., 2004). Under climate change, rising temperatures are changing the geographical distribution of disease vectors
which are migrating to new areas and higher altitudes. For example, migration of the malaria mosquito to higher
altitudes will expose large numbers of previously unexposed people to infection in the densely populated East African
highlands (Boko et al., 2007).
Future climate variability will also interact with other stresses and vulnerabilities such as HIV/AIDS (which is already
reducing life expectancy in many African countries) and conflict and war (Harrus and Baneth, 2005), resulting in
increased susceptibility and risk to infectious diseases (e.g. cholera and diahrrhoea) and malnutrition for adults and
children (WHO, 2004).
Climate change is an added stress to already threatened habitats, ecosystems and species in Africa, and is
likely to trigger species migration and lead to habitat reduction. Up to 50 per cent of Africa’s total biodiversity
is at risk due to reduced habitat and other human-induced pressures (Boko et al., 2007). The latter include
land-use conversion due to agricultural expansion and subsequent destruction of habitat; pollution; poaching;
civil war; high rates of land use change; population growth and the introduction of exotic species. For example,
the habitat of the great apes, including the western lowland Gorilla – identified as critically endangered on the
International Union for Conservation of Nature’s (IUCN) red list of threatened species, is likely to seriously
decline between 2002 and 2032.
Future sea level rise has the potential to cause huge impacts on the African coastlines including the already
degraded coral reefs on the Eastern coast. National communications indicate that the coastal infrastructure in
30 percent of Africa’s coastal countries, including the Gulf of Guinea, Senegal, Gambia, Egypt, and along the
East-Southern African coast, is at risk of partial or complete inundation due to accelerated sea level rise.
In Tanzania, a sea level rise of 50 cm would inundate over 2,000 km2 of land, costing around USD 51 million
(UNEP, 2002). Future sea level rise also threatens lagoons and mangrove forests of both eastern and western
Africa, and is likely to impact urban centres and ports, such as Cape Town, Maputo, and Dar Es-Salaam.
Climate change can promote loss of species diversity and shifts in species range. Concerning climate change effects on terrestrial ecosystems,
future changes in rainfall and temperature are likely to result in changes in plant and animal species composition and diversity, and shifts of
species range (UNEP 2004). Historically, climate fluctuation has lead to remarkable shifts in the evolution and geographical distributions of
species and ecosystems in order for species to adapt (Malcolm et al. 2002, Jansen et al. 2007). Ecosystems are dynamic and plant and animal
species evolve and adapt in-situ or migrate or shift in order to find suitable habitats requirements (e.g. evolutionary examples are galapagis
finches and Lake Malawi cichlids); this may mean that in some locations the geographical range of suitable habitats will shift outside protected
area boundaries. Shifts in species range could have impacts on species population size and could lead to numerous localized extinctions or
expansions, depending on favourable conditions. These consequences could be exacerbated if climate change restricts the range of a species to
just a few key sites and an extreme weather event occurs, thus driving up extinction rates even further (Erasmus et al. 2002). Moreover,
fragmentation of habitats could easily disrupt the connectedness among species and increase the difficulties for migrating.
Climate change may also alter ecosystems resilience. If ecosystems resilience is lost, future climate change effects on ecosystems could lead to
irreversible changes in the state of ecological and social systems (Thompson et al. 2009). Uncertainty around potential impacts of future climate
change on ecosystems is compounded by possible increases in productivity due to climate change, which may also have effects on ecosystems
resilience, as these may occur in certain terrestrial ecosystems through likely atmospheric CO2-fertilisation effects and/or modest warming.
Monitoring ecological changes related to climate change will help understanding better possible thresholds and tipping-points and allow
informed decision making on wise management of natural ecosystems.
What is more? Climate change impacts include loss of particular species. According to Mooney et al (2009), not all species are equal in terms of
how ecosystems function. Abundant and dominant species are generally the major controllers of system function, yet less abundant
species may nonetheless have very consequential effects on ecosystems: such as ecosystem engineers and keystone species. The presence of rare
species may enhance invasion resistance in a community and further, a given species may be rare at the present time, but change dramatically in
abundance and importance at other times, supporting the idea of biodiversity as
‘ecosystem insurance’.
In Africa, studies have shown that around 5,000 African plant species and over 50% of bird and mammal species will be
seriously affected or even lost by the end of this century (Fischlin et al. 2007). McClean et al. (2005) estimated
substantial reductions in areas of suitable climate for 81-97% of the 5,197 African species examined, with 25-42% having
lost all area by 2085. Moreover, the IPCC (Fischlin et al. 2007) estimates that by 2100 the productivity of Africa’s lakes
will decline by 20 to 30%. As temperature rises, stress on ecosystems is expected to escalate quickly, compounded by
other stressors such as infestations of invasive species, over harvesting, land-use change, water scarcity, etc (Gaston et
al. 2003). All these stressors, including climate change, are driven by indirect drivers such as population and economic
growth, which will increase the demand for food, water, and land within the next decades.
An example of abrupt environmental change in Tanzania that could be considered a signal of the potential effects of
climate change and rising sea surface temperatures is the 1998 Indian Ocean coral bleaching event which reduced coral
cover in most reefs of the country, with mortalities of up to 90% in many shallow areas (Wilkinson et al. 1999,
McClanahan et al. 2001). The year 1998 saw the strongest El Nino ever recorded in the region, resulting in very high
water temperatures in the tropical Indian Ocean, with temperatures of 3 to 5 degree C above normal. Despite not all
fisheries were susceptible to the immediate effects of coral bleaching and mortality, loss of habitat structure following
coral mortality can be expected to affect up to almost 60% of species resulting in changes in the structure of reef
habitats and in considerable reduction of the goods and services provided by reefs (Jones et al. 2004, Pratchett et al.
2008, Cinner et al. 2009). There is strong international consensus that climate change and ocean acidification are already
affecting shallow water corals (Eakin et al. 2009).
Certain groups of species are by their very nature major players in any ecosystem; a case in point is the community
structuring role of top carnivores. These are particularly susceptible to local, and global extinction, mostly due to human
activities, particularly habitat loss, but also due to hunting. Because of their generally large home ranges these types of
species are particularly susceptible to habitat fragmentation often resulting in the loss of an entire trophic level with
profound impacts on ecosystem functioning. Meyers et al., discussed a dramatic example of this, documenting the
consequences of declines in populations of great sharks in the coastal northwest Atlantic ecosystem. The decline
resulted in increases in the population of rays, skates and small sharks. The increase in cownose ray was sufficient to
reduce their scallop prey to a level that the fishery for them was terminated after a century of operation. Other
examples of dramatic top–down control of ecosystem structure and process have been shown in marine systems as well
as freshwater and terrestrial systems. Experiments have shown that the greater the diversity of functional groups in a
system the less is the likelihood of cascading species extinctions. If both functional diversity (how species control in an
ecosystem processes) and response diversity (how species respond to stressors) within functional groups are high, an
ecosystem may exhibit a great deal of resilience in the face of environmental changes. A meta-analysis of work in eight
different European grasslands suggests that different species have a disproportionate impact on different functions so
that maintenance of multi-functional ecosystems may require maintenance of high species diversity.
The documented losses at the species and population level are extensive and future trends from past drivers of change
are continuing for the most part unabated. According to the IUCN Red List update in 2008 over 900 species have gone
extinct since 1500 (http://www.iucnredlist.org/
static/stats) including many vertebrates, invertebrates and plants. This is certainly an underestimate since our
knowledge of many groups is extremely poor and further the time line for inclusion in the list can be lengthy.
We know most about the world’s bird species. Since 1500 we have lost at least 150 species, and at present one in eight bird species
are threatened with global extinction. Across 20 European countries 45% of the bird species have had population decreases. In the
grasslands of the United States 55% of the bird species are showing population declines and 48% are of conservation concern.
The picture for mammals is equally bleak. Estimates are that one-quarter of the over 5000 species of mammals are threatened with
extinction (76 species have gone extinct since 1500) and one-half of all of species have declining populations. For land mammals
the principal driver of risk is habitat loss followed by harvesting. For marine mammals by-catch and pollution are the biggest
threats. Extinction rates of freshwater fauna are estimated to be at least five times higher than terrestrial or avian species owing to
the multiple stressors of overfishing, dam construction, water diversion and pollution.
Climate change may alter agro-ecological zones. Increases in temperature and changes in rainfall are expected to alter the
distribution of the agro-ecological zones. For example, under climate change most of the forests across Tanzania are expected to
shift towards drier regimes: from subtropical dry forest, subtropical wet forest, and subtropical thorn woodland to tropical very dry
forest, tropical dry forest, and small areas of tropical moist forest respectively (Tanzania First National Communication 2003).
Currently, assessments of climate change impacts on forests do not explicitly account for the potential effects of climate change on
disturbances such as fire. Altered fire regimes could contribute to warmer and drier conditions intensifying the risks for forests
(Agrawala et al. 2003). For example, decline in precipitation coupled with a local warming can increase the intensity and risk of
forest fires on Mount Kilimanjaro. Forest fires have already affected clouds over forests in the mountain, which play a key role in the
hydrological balance of the water catchment. According to Agrawala et al. (2003), a continuation of current trends in climatic
changes, fire frequency, and human influence could result in the loss of most of the remaining subalpine Erica forests and the water
budgets of the high altitude basins in Mount Kilimanjaro, putting at risk the long-term sustainability of the valuable resources of
this ecosystem. Fire in wetlands during excessive dry periods would have the similar detrimental effects.
Climate change impacts on human activities
Current and potential impacts of climate change on ecosystems also affect human activities. For example, large portions of the
population became vulnerable to climate change because of their limited livelihood base, poor access to markets and services and
their dependence on nature for food, water supply, energy, transport, healthcare and social welfare, and because of the
weaknesses in the institutions that govern them
Climatically induced changes can have implications not only for agriculture and water supply but also for the tourism sector. For
example, changes in the spread and growth of natural vegetation due to climate change present a risk to the habitats of Tanzania’s
wildlife, an important source of cultural identity within the country, as well as being central to Tanzania’s tourist economy and to
poverty reduction as provisioning local bushmeat.
This plays out in the context of increasing habitat fragmentation associated with human interventions and land use changes
preventing migration to greener pastures. Tourism activities may also be affected by the severity and frequency of extreme events
experienced across a country leading to the loss of ecosystems resilience to absorb disturbances. Ecosystem degradation would
also lead to a decline or a change in biodiversity with multiple negative feedbacks (e.g. loss of coral reefs can jeopardize tourism
and shoreline protection). Tourism and other economic sectors may also be affected by the threat of certain areas such as lowland
regions and the Niger Delta region in Nigeria experiencing more intense rain events which increases the risks associated with
flooding and resultant damage to housing, public and tourism-oriented infrastructure. Extreme events may also damage hydroelectric plants and electricity supply to tourism services like hotels, restaurants, and night spots. Moreover, the loss of sandy beach
areas associated with sea level rise and increased storm surges can have large implications for tourism, especially in the islands
where the economy depends on sea side tourism.
ECOSYSTEM-BASED APPROACHES FOR ADAPTATION TO CLIMATE CHANGE
We now know that understanding the interaction between climate change and ecosystem management provides the key to securing
adequate ecosystem services to human wellbeing (UNEP, 2009). Climate change can at regional or global scale be amplified or modified
through responses of different ecosystems. Science has shown that:
 Ecosystems form the fundamental unit of life support for humans and all other forms of life. Their functions are primarily driven by the
climate.
 Healthy ecosystems support human well being through the provision of ecosystem services. These include the supply of food, fresh
water, clean air, fertile soil, biological diversity, and the ability to regulate the climate through energy transfer and the global
biogeochemical cycles, including the carbon cycle, but also the nitrogen and phosphorous cycles.
 The ability of ecosystems to function and provide these services is determined by many factors including their biological diversity,
ecological and evolutionary processes, climatic inputs of energy and water, anthropogenic impacts related to economic activities, and
their interactions.
 Depending on the nature of change and the condition of the system due to human perturbation, climate variability and change can pose
substantial risks to ecosystem health, the provision of ecosystem services and therefore human and biodiversity well being.
 Greater value to support ecosystem-based management decision making can be gained through the integration of multiple information
types with climate and ecosystem information forming the basis for establishing the boundaries for a sustainable human society.
Therefore, providing appropriate adaptation to climate change requires adopting the ecosystem approach. The scientific understanding of the impact of climate change on ecosystem is now
sufficiently clear to begin taking steps to prepare for climate change and to slow it. Human actions over the next few decades will have a major influence on the magnitude and rate of future
warming. Large, disruptive changes are much more likely if greenhouse gases are allowed to continue building up in the atmosphere at their present rate. However, reducing greenhouse gas
emissions will require strong national and international commitments, technological innovation, and human willpower.
Below are the major principles of this approach (IUCN, 2004).
The 12 principles of the Ecosystem Approach
1. The objectives of management of land, water and living resources are a matter of societal choice.
2. Management should be decentralized to the lowest appropriate level.
3. Ecosystem managers should consider the effects (actual or potential) of their activities on adjacent and other ecosystems.
4. Recognizing potential gains from management, there is usually a need to understand and manage the ecosystem in an economic context. Any such ecosystem-management programme should:
(i)reduce those market distortions that adversely affect biological diversity;
(ii)align incentives to promote biodiversity conservation and sustainable use; and
(iii)internalize costs and benefits in the given ecosystem to the extent feasible.
5. Conservation of ecosystem structure and functioning, to maintain ecosystem services, should be a priority target of the ecosystem approach.
6. Ecosystems must be managed within the limits of their functioning.
7. The ecosystem approach should be undertaken at the appropriate spatial and temporal scales.
8. Recognizing the varying temporal scales and lag-effects that characterize ecosystem processes, objectives for ecosystem management should be set for the long term.
9. Management must recognize that change is inevitable.
10.The ecosystem approach should seek the appropriate balance between, and integration of, conservation and use of biological diversity.
11.The ecosystem approach should consider all forms of relevant information, including scientific and indigenous and local knowledge, innovations and practices.
12.The ecosystem approach should involve all relevant sectors of society and scientific disciplines.
Five steps in the implementation of the ecosystem approach
IUCN has recommended that in adopting the ecosystem approach in resolving climate change impacts, the following five steps are
necessary:
1. Determining the main stakeholders, defining the ecosystem area, and developing the relationship between them.
2. Characterizing the structure and function of the ecosystem, and setting in place mechanisms to manage and monitor it.
3. Identifying the important economic issues that will affect the ecosystem and its inhabitants.
4. Determining the likely impact of the ecosystem on adjacent ecosystems.
5. Deciding on long-term goals, and flexible ways of reaching them.
The Dynamic Ecosystem-based Adaptation Pathways Framework
Integrating the ecosystem approach with human activities lead us to adopt what is now termed the dynamic ecosystem-based adaptation
pathway framework (EbA). This framework relates to the management of ecosystems within interlinked social-ecological systems to
enhance ecosystem processes and services that are essential for adaptation to multiple stressors, including climate change (CBD 2009,
Chapin et al. 2009, Piran et al. 2009). In other words, EbA integrates the management of ecosystems and biodiversity into an overall
strategy to help people and ecosystems adapt to the adverse impacts of global change, such as changing climatic conditions (Colls et al.
2009).
This approach depends highly on healthy and resilient ecosystems, which are able to deliver a bundle of ecosystem
services to support adaptation and well-being of societies in the face of various pressures. These pressures can be
internal to the social-ecological system (e.g. population and economic growth), or external, such as climate variability in
the short term or climate change in the longer term (Piran et al. 2009). At the core of this approach lies the recognition
of existing interactions and feedbacks between human and ecological systems and the need to understand these to
enhance benefit flows from the system (UNEP-WCMC 2010). EbA has the potential to generate multiple environmental
and societal benefits, while reconciling short and long-term priorities (TEEB 2009). For instance, EbA can be a synergistic
approach that reconciles mitigation objectives by enhancing carbon stocks, with cost effective management of climatic
risks, and conservation objectives by preserving natural ecosystems and biodiversity (TEEB 2009).
Enhancing the capacity of ecosystems to generate essential services for climate change adaptation requires that they be
managed as components of a larger seascape-landscape of which human activities are part. The Dynamic EbA Pathways
Framework is a conceptual framework based on an adaptive ecosystem management approach to enhance and
maintain ecological processes and ecosystem services at the landscape level. It combines multi-functional land uses and
conservation of natural capita to enhance multi-scale benefits from ecosystems that help social-ecological systems adapt
to changing and multiple stressors, including climate change. It is based on the recognition that the ability of ecosystems
to adapt naturally can be affected by the quality, quantity and nature of changes in the landscape, and that beyond
certain thresholds natural ecosystems may be unable to adapt at all, hence active human intervention for planned
adaptation is necessary. To facilitate the adjustment of human societies and ecological systems to changing conditions
and multiple stressors, the Dynamic EbA Pathways Framework combines EbA strategies (active core, in blue), with
flexible enabling mechanisms and adaptive processes (supportive milieu, in green).
Following this approach, a number of potential ecosystem-based adaptation strategies are available, which include (Devisscher, 2010):
 To maintain and increase ecosystem resilience: enhancing the ability of ecosystems to absorb and recover from change while maintaining and
increasing biodiversity (e.g. identifying resilient coral reefs that can recover from disturbances such as bleaching events or storms, while at the same
time protecting the shorelines from wave forcing and tsunamis).
 To accommodate the potential impacts of climate change: considering both gradual change and extreme events (e.g. planning projects and
programmes that consider the ensemble of possible future climate scenarios for the specific location, while building socio-institutional and ecological
adaptive capacity).
 To facilitate knowledge transfer and action between partners, sectors and countries: successful adaptation requires ecosystem and biodiversity
conservation to be integrated with other sectoral and local government management activities (e.g. mainstreaming community-based natural resources
management – CBNRM – in all sectors)
 To develop the knowledge/evidence base and plan strategically: to effectively plan for an uncertain future, the best available evidence is needed to
help social ecological systems adapt (e.g. developing a knowledge management system that will help share up-to-date and credible information
among decision-makers and practitioners and promote an open-dialogue to promote social learning and collective generation of knowledge)
 To use adaptive management: to deal with uncertainty using a flexible approach for effective conservation and adaptation planning, based on iterative
processes of learning by doing, reviewing, and refining (e.g. considering the dynamic interactions between social and ecological systems, lessons
learned, and changes over time in land-use planning processes, both in reserve land and in common land).
 To enhance vulnerability assessments and monitoring systems: to allow evidence to be collated, existing schemes to be strengthened and new
requirements incorporated (e.g. introducing programmes to study response of species to climate change (i.e. physiological, behavioral, demographic)
into CBNRM in order to create awareness, while systematically obtaining data on key indicators of change over continued periods of time)
Moreover, there is a range of potential ecosystem-based adaptation measures that relate to the management of ecosystems to address existing and future climate risks.
They include:
 Reducing and managing existing stresses, such as fragmentation, pollution, over harvesting, population encroachment, habitat conversion and invasive species (e.g.
applying an ecosystem-based approach to land-use planning such as integrated coastal management, where interactions between different land-use types are recognized
and negative effects from one to the other are minimized).
 Maintaining ecosystem structure and function as a means to ensure healthy and genetically diverse populations able to adapt to climate change (e.g. adopting a
landscape-level approach, where ecosystems are managed as components of a mosaic of multiple land-uses and human settlements).
 Increasing the size and/or number of reserves or increasing habitat heterogeneity within reserves and between reserves (e.g. expanding state reserves to include more
gradients of latitude or altitude to help for species migration, or by reaching agreements with communities to set aside some land for conservation using economic
incentives such as payment for ecosystem services)
 Building in buffer zones to existing reserves (e.g. protecting land around wetlands, rivers, or other ecosystem that are key for climate adaptation and vulnerable to
climate and social change).
 Increasing connectivity and landscape permeability (e.g. developing biological corridors or stepping stones to link areas, removing barriers for dispersal, linking of
reserves and refugia, or encouraging and up-scaling sustainable management practices such as agro-forestry, community-based tourism wildlife management)
 Assessing, modelling, and experimenting at different spatial scales for improved predictive capacity and simulation outcomes (e.g integrating dynamic vegetation
modelling and bio-climate envelope modelling with social behaviour modelling).
 Conducting restoration and rehabilitation of habitats and ecosystems with high adaptation value (e.g identifying ecosystem services that are key for climate adaptation,
and introducing regulation or economic incentives to maintain or enhance these services with the involvement of relevant actors that would ensure sustainable natural
 Translocation or reintroduction of species at risk of extinction to new areas that are climatically suitable for their existence (e.g. establishment of seed banks with
climate-resilient species, zoos, captive breeding for release into wild).
These EbA measures can be implemented through a series of mechanisms that have the potential to enhance ecosystem services, including (Devisscher, 2010):
 Regulation: robust regulatory frameworks and enforcement mechanisms, including standards, codes, compliance and liability regimes, that can help reduce threats to
biodiversity and ecosystems, while enhancing ecological services for climate adaptation. For example, the National Environmental Policy, Forestry Policy, Wildlife
Policy, National Forest Programme, Integrated Coastal Zone Management Strategy, Agricultural Sector Development Strategy, Forestry Management Act etc are
regulatory mechanisms that aim at conserving natural resources in the country. These mechanisms need to be flexible to accommodate new available information, and
moving targets based on better understanding of the dynamics between biophysical and social systems.
 Economic instruments: that can influence or incentivize markets, practitioners, and society to adopt them. The pool of economic instruments includes mechanisms
such as innovative tax and fiscal policies, performance standards, verification systems, compensation, subsidies, intergovernmental fiscal transfers, government
spending, debt-for-nature swaps, among others.
 Integration: integration of policies and mainstreaming of ecosystem management into the planning process would need to adopt a multi-scale (i.e. national, regional,
local) and cross-sectoral approach. Integrating policies would increase the cost-effectiveness of investment aimed at enhancing the flow of ecological services with cobenefits that would support multiple objectives shared across different stakeholder groups.
 Market-based mechanisms: create incentives and reward efforts for maintaining or enhancing multiple ecological services. These mechanisms are highly flexible and
can be established and used by different actors and at different scales. For example, market-based mechanisms in the form of payment for ecosystem services can be
applied to maintain the flow of one or a bundle of services provided by ecosystems. Such a mechanism can be implemented to promote REDD+ in the continent, or to
encourage soil conservation practices for the protection of water catchments, or to support the protection of refugia for the conservation of wildlife.
 Green Investment: finance flows targeting green investment are growing (e.g. global carbon fund). Green investment can enhance ecological functions and
services supporting initiatives such as bio-commerce (e.g. organic production, fair trade, eco-tourism); certification and labeling schemes (e.g. ecologically
certified production, sustainable management of forests with the Forest Stewardship Council [FSC]); corporate social responsibility (e.g. private and public
businesses monitoring compliance with ethical standards and international norms like ISOs); green public procurement (e.g. contracting entities that take
environmental issues into account when tendering for goods or services); among others.
To deal with uncertainty, these mechanisms will support the implementation of EbA measures and strategies through adaptive processes that include (Devisscher,
2010):
 Building research capacity and supporting knowledge sharing: orchestrating a number of processes that help to improve multi-disciplinary research capacity, to
monitor relationships and feedbacks, to generate and share new information and knowledge, and to integrate new understandings into practices.
 Promoting technology and innovation: technology innovation, commercialization and transfer have the potential to support adaptation processes, while at the
same time capturing economic value ‘at home’ through entrepreneurship, job creation and new venture development. Technology deployment and transfer do not
only depend on technological means and financial investment, but also on the decision context, systems of thought, belief and knowledge that will determine the
capacity of a society to innovate and adopt this approach to find solutions or support decisions for adaptation.
 Applying adaptive governance: this involves an interactive process that facilitates flexibly adjusting decisions, plans and actions to the changing environmental
and social contexts, considering the complex dynamics between ecosystems and interactions of social-ecological systems. A robust way of starting the learning
process under this approach in the context of EbA is to build on ‘no-regret’ actions that would lead to multiple benefits in ecological, social, and economic terms
under different possible futures. Adaptive governance for EbA would require closer links and collaboration between actors and organizations at different
governance levels, integration of policies, better coordination of sectoral plans, and assimilation of the ecosystem-based approach into planning processes.
 Supporting socio-institutional change: governance and planning of EbA pathways across multiple governance levels will trigger social and institutional
reorganization, particularly in face of rapid change. In this context, bridging organizations will evolve to bring together a range of actors and formal and informal
institutions with a diversity of knowledge. Such organizations will stimulate the development of interactive spaces where actors and social networks will
coalesce around common interests and share and produce collective ideas and knowledge that will enhance the process of social learning. Better understanding
and new configurations of EbA pathways stemming from this process and through the implementation, evaluation and adjusting of EbA strategies will lead to the
development of new institutions and/or organizational change within existing institutional arrangements and social networks.
Given the high uncertainty involved in long-term planning, and the non-linear behaviour of complex social-ecological systems, the Dynamic EbA Pathways Framework
uses a step-based approach to explore the range of potential EbA pathways that can be adopted over time. This approach recognizes that not all adaptation decisions are
needed now and enables socio-institutional learning, adaptive management, and better understanding over time. By doing so, it deals with the uncertainty inherent to
possible futures, overlaps between EbA pathways, synergistic and antagonistic cross-sectoral interactions of adaptation actions, and multiple stressors affecting the socialecological systems. The steps relate to actions that can be grouped in four categories:
 actions that can be considered no regrets measures,
 actions that relate to building institutional capacity,
 pilot actions, and
 actions that account for ecosystem-based transformation.
Costs of Ecosystem-based Adaptation
Ecosystem-based adaptation costs relate to expenditure associated with actions taken to enhance ecosystem services that can help avoid or minimize the negative impacts
of climate change on both ecosystems and human societies. It is based on the premise that autonomous adaptation of ecosystems and species will not be sufficient to
withstand future impacts of climate change and therefore human planned actions are indispensable to maintain or enhance the ecological processes and ecosystem
services necessary for climate change adaptation of social-ecological systems.
Estimating the costs of EbA is complicated due to several reasons.
The first one relates to the uncertainty associated with the direct and indirect costs of climate change impacts (e.g. direct costs of increased natural disasters, indirect costs
for development, as climate impacts can become obstacles in the achievement of the MDGs and other development processes). Without knowing with certainty the
expected damage, it is difficult to calculate the level that could be avoided by adaptation. Most impacts are projected to increase non-linearly with climate change, and
adaptation costs to increase correspondingly (Parry et al. 2009). In this context, it is helpful to analyze costs of adapting to varying amounts of impact, thus providing a
choice range for preparedness to pay and the residual impact that adaptation is not likely prevent, indicating residual damage costs that need to be anticipated.
Estimating costs of actions that can facilitate adaptation considering multiple possible futures needs to recognize (Devisscher, 2010):
 synergies with mitigation;
 the limits to adaptation (e.g. impacts that cannot be avoided even if unlimited funding is available due to, for example, lack of technology); and
 the boundaries of willingness to pay for adaptation (e.g. priority actions that are economically feasible, budget constraints, national and global visions).
A second challenge that complicates the assessment of EbA costs is valuing “soft” measures (Parry et al. 2009). While it is easier to estimate the costs of measures like
infrastructure to avoid soil erosion in water catchment areas, it is more difficult to assess behavioral change and organizational capacity that lead to a decrease of deforestation
and introduction of more sustainable production practices. EbA combines both measures, but relies heavily on “soft” adaptation measures through flexible mechanisms.
A third challenge is that EbA largely depends on the adaptive capacity of socialecological systems, which is based on interactions and feedbacks between social and biophysical
systems that are not well understood yet. Nor are thresholds and tipping-points that could transform the state of these systems and the nature of interactions.
A fourth challenge is the poor understanding of the full economic value of ecosystem services. Benefits from EbA are based on services provided by ecosystems for climate
change adaptation. Although economic valuation methods for specific ecosystem services exist, efforts to value multiple services of ecosystems for a range of users at different
scales are still in their infancy, and work to integrate these results into economic assessments for planning at the landscape-level is only starting.
A fifth challenge, and probably one of the most important ones, is the close interaction between ecosystems and other sectors. It is probably easier to cost adaptation actions that
focus on preserving the existence of particular ecosystems and species (e.g. setting or expanding the network of protected areas) than actions that enhance ecosystem services at
the landscape-level to facilitate climate adaptation (e.g. increasing permeability of the wider landscape matrix encompassing multi-functional land-uses). The latter is more
complicated because it can incur in double counting, as land-use changes or different sectoral adaptation strategies can interact synergistically or antagonistically affecting
ecosystem processes that enable or prevent ecosystem services (Berry 2007, Parry et al. 2009). This interaction can reduce or add to the costs of EbA.
Recognizing the above complexities is important when costing ecosystem-based adaptation. Their acknowledgment leads to more robust decisions that can be improved through
iterative processes of learning and refinement over time. Under this approach, it is also important to account for current financial deficits, sensitivities and differentiated
vulnerabilities of social and ecological systems, which need to be addressed as the first step to build adaptive capacity.
BARRIERS AND RESPONSES TO SUSTAINABLE ECOSYSTEM MANAGEMENT
Past actions to slow or reverse the degradation of ecosystems have yielded significant benefits, but these improvements have generally not kept pace with growing pressures and
demands. For example, more than 100,000 protected areas globally(including strictly protected areas such as national parks as well as areas managed for the sustainable use of
natural ecosystems, including timber or wildlife harvest) covering about 11.7% of the terrestrial surface have now been established, and these play an important role in the
conservation of biodiversity and ecosystem services (although important gaps in the distribution of protected areas remain, particularly in marine and freshwater systems).
Technological advances have also helped lessen the increase in pressure on ecosystems caused per unit increase in demand for ecosystem services.
An effective set of responses to ensure the sustainable management of ecosystems must address and overcome barriers related to (Devisscher, 2010):

Inappropriate institutional and governance arrangements, including the presence of corruption and weak systems of regulation and accountability.

Market failures and the misalignment of economic incentives.

Social and behavioral factors, including the lack of political and economic power of some groups (such as poor people, women, and indigenous peoples) that are particularly
dependent on ecosystem services or harmed by their degradation.

Underinvestment in the development and diffusion of technologies that could increase the efficiency of use of ecosystem services and could reduce the harmful impacts of
various drivers of ecosystem change.

Insufficient knowledge (as well as the poor use of existing knowledge) concerning ecosystem services and management, policy, technological, behavioral, and institutional
responses that could enhance benefits from these services while conserving resources.
All these barriers are further compounded by weak human and institutional capacity related to the assessment and management of ecosystem services underinvestment in the
regulation and management of their use, lack of public awareness, and lack of awareness among decision-makers of both the threats posed by the degradation of ecosystem
services and the opportunities that more sustainable management of ecosystems could provide.
Response Actions to Address the Barriers
The response options to address these barriers include (Devisscher, 2010):

Institutions and Governance

Economics and Incentives

Social and Behavioral

Technological Responses

Knowledge Responses
Institutions and Governance
Changes in institutional and environmental governance frameworks are sometimes required to create the enabling conditions for effective
management of ecosystems, while in other cases existing institutions could meet these needs but face significant barriers. Many existing
institutions at both the global and the national level have the mandate to address the degradation of ecosystem services but face a variety of
challenges in doing so related in part to the need for greater cooperation across sectors and the need for coordinated responses at multiple
scales.
Economics and Incentives
Economic and financial interventions provide powerful instruments to regulate the use of ecosystem goods and services. Because many
ecosystem services are not traded in markets, markets fail to provide appropriate signals that might otherwise contribute to the efficient
allocation and sustainable use of the services. A wide range of opportunities exists to influence human behavior to address this challenge in the
form of economic and financial instruments. However, market mechanisms and most economic instruments can only work effectively if
supporting institutions are in place, and thus there is a need to build institutional capacity to enable more widespread use of these mechanisms.
Social and Behavioral Responses
Social and behavioral responses—including population policy, public education, civil society actions, and empowerment of communities, women,
and youth—can be instrumental in responding to the problem of ecosystem degradation. These are generally interventions that stakeholders
initiate and execute through exercising their procedural or democratic rights in efforts to improve ecosystems and human well-being.
Technological Responses
Given the growing demands for ecosystem services and other increased pressures on ecosystems, the development and diffusion of technologies
designed to increase the efficiency of resource use or reduce the impacts of drivers such as climate change and nutrient loading are essential.
Technological change has been essential for meeting growing demands for some ecosystem services, and technology holds considerable promise
to help meet future growth in demand. Technologies already exist for reduction of nutrient pollution at reasonable costs—including technologies
to reduce point source emissions, changes in crop management practices, and precision farming techniques to help control the application of
fertilizers to a field, for example. New policies are needed for these tools to be applied on a sufficient scale to slow and ultimately reverse the
increase in nutrient loading (even while increasing nutrient application in regions such as sub-Saharan Africa where too little fertilizer is being
applied). However, negative impacts on ecosystems and human well-being have sometimes resulted from new technologies, and thus careful
assessment is needed prior to their introduction.
Promotion of technologies to increase energy efficiency and reduce greenhouse gas emissions.
Significant reductions in net greenhouse gas emissions are technically feasible due to an extensive array of technologies in the
energy supply, energy demand, and waste management sectors. Reducing projected emissions will require a portfolio of energy
production technologies ranging from fuel switching (coal/oil to gas) and increased power plant efficiency to increased use of
renewable energy technologies, complemented by more efficient use of energy in the transportation, buildings, and industry
sectors. It will also involve the development and implementation of supporting institutions and policies to overcome barriers to the
diffusion of these technologies into the marketplace, increased public and private sector funding for research and development,
and effective technology transfer
Knowledge Responses
Effective management of ecosystems is constrained both by the lack of knowledge and information about different aspects of
ecosystems and by the failure to use adequately the information that does exist in support of management decisions. In most
regions, for example, relatively limited information exists about the status and economic value of most ecosystem services, and
their depletion is rarely tracked in national economic accounts. Basic global data on the extent and trend in different types of
ecosystems and land use are surprisingly scarce. Models used to project future environmental and economic conditions have
limited capability of incorporating ecological “feedbacks,” including non-linear changes in ecosystems, as well as behavioral
feedbacks such as learning that may take place through adaptive management of ecosystems.
At the same time, decision-makers do not use all of the relevant information that is available. This is due in part to institutional
failures that prevent existing policy-relevant scientific information from being made available to decision-makers and in part to the
failure to incorporate other forms of knowledge and information (such as traditional knowledge and practitioners’ knowledge) that
are often of considerable value for ecosystem management.
The challenge for all is to make better use of the management of ecosystems in resolving human problems.
ACKNOWLEDGEMENTS
I would like to thank most sincerely the International Organising Committee (IOC) for the 2nd Joint
International Conference organized by the University of Ilorin, Nigeria and University of Cape Coast,
Ghana for the privilege and honour to attend this conference.
My special thanks go to Professor K.L. Ayorinde, the Deputy Vice-Chancellor (Academic) and
Chairman, International Organising Committee of this conference and Professor F.A. Oladele of the
University of Ilorin for their help in various ways.
I would like to express my particular appreciation to Dr. J.F.K. Akinbami, Mr. Victor Imevbore, and my
wife, Mrs. Mary Imevbore for their help and comments on the manuscript. My thanks also go to
Ayobami Olawale who helped in typing the manuscript.
Appendix I: GREENHOUSE GASES WARM THE PLANET
These gases are:
Carbon dioxide (CO2) has both natural and human sources, but CO2 levels are increasing primarily because of the use of fossil fuels, with deforestation and other land use changes also
making a contribution. Increases in carbon dioxide are the single largest climate forcing contributing to global warming.
Methane (CH4) has both human and natural sources, and levels have risen significantly since pre-industrial times due to human activities such as raising livestock, growing rice, filling
landfills, and using natural gas (which releases methane when it is extracted and transported).
Nitrous oxide (N2O) concentrations have risen primarily because of agricultural activities and land use changes.
Ozone (O3) forms naturally in the upper atmosphere, where it creates a protective shield that intercepts damaging ultraviolet radiation from the Sun. However, ozone produced near
the Earth’s surface via reactions involving carbon monoxide, hydrocarbons, nitrogen oxide, and other pollutants is harmful to both animals and plants and has a warming effect. The
concentration of O3 in the lower atmosphere is increasing as a result of human activities.
Halocarbons, including chlorofluorocarbons (CFCs), are chemicals that have been used for a variety of applications, such as refrigerants and fire retardants. In addition to being potent
greenhouse gases, CFCs also damage the ozone layer. The production of most CFCs is now banned, so their concentrations are starting to decline.
Other human activities can also force temperature changes:
Most aerosols (airborne particles and droplets), such as sulfate (SO4), cool the planet by reflecting sunlight back to space. Some aerosols also cool the Earth indirectly by increasing the
amount of sunlight reflected by clouds. Human activities, such as industrial processes, produce many different kinds of aerosols. The total cooling that these aerosols produce is one of
the greatest remaining uncertainties in understanding present and future climate change.
Black carbon particles or “soot,” produced when fossil fuels or vegetation are burned, generally have a warming effect because they absorb incoming solar radiation. Black carbon
particles settling on snow or ice are a particularly potent warmer.
Deforestation and other changes in land use modify the amount of sunlight reflected back to space from the Earth’s surface. Changes in land use can lead to positive and negative
climate forcing locally, but the net global effect is a slight cooling.
Natural processes also affect the Earth’s temperature:
The Sun is Earth’s main energy source. The Sun’s output is nearly constant, but small changes over an extended period of time can lead to climate change. In addition, slow changes in
the Earth’s orbit affect how the Sun’s energy is distributed across the planet, giving rise to ice ages and other long-term climate fluctuations over many thousands of years. The Sun’s
output has not increased over the past 30 years, so it cannot be responsible for recent warming.
Volcanic eruptions emit many gases. One of the most important of these is sulfur dioxide (SO2), which, once in the atmosphere, forms sulfate aerosol (SO4). Large volcanic eruptions
can cool the Earth slightly for several years, until the sulfate particles settle out of the atmosphere.
Appendix II: EFFECTS OF CLIMATE CHANGE THAT WE SEE HAPPENING WORLDWIDE.
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Sea level is rising. During the 20th century, sea level rose about 15 cm (6 inches) due to melting glacier ice and expansion of warmer seawater. Models predict that sea
level may rise as much as 59 cm (23 inches) during the 21st Century, threatening coastal communities, wetlands, and coral reefs.
Arctic sea ice is melting. The summer thickness of sea ice is about half of what it was in 1950. Melting ice may lead to changes in ocean circulation. Melting sea ice is
speeding up warming in the Arctic.
Glaciers and permafrost are melting. Over the past 100 years, mountain glaciers in all areas of the world have decreased in size and so has the amount of permafrost in the
Arctic. Greenland's ice sheet is melting faster too.
Sea-surface temperatures are warming. Warmer waters in the shallow oceans have contributed to the death of about a quarter of the world's coral reefs in the last few
decades. Many of the coral animals died after weakened by bleaching, a process tied to warmed waters.
The temperatures of large lakes are warming. The temperatures of large lakes world-wide have risen dramatically. Temperature rises have increased algal blooms in lakes,
favor invasive species, increase stratification in lakes and lower lake levels.
Heavier rainfall causes flooding in many regions. Warmer temperatures have led to more intense rainfall events in some areas. This can cause flooding.
Extreme drought is increasing. Higher temperatures cause a higher rate of evaporation and more drought in some areas of the world.
Crops are withering. Increased temperatures and extreme drought are causing a decline in crop productivity around the world. Decreased crop productivity can mean food
shortages which have many social implications.
Hurricanes have changed in frequency and strength. There is evidence that the number of intense hurricanes has increased in the Atlantic since 1970. Scientists continue to
study whether climate is the cause.
More frequent heat waves. It is likely that heat waves have become more common in more areas of the world.
Warmer temperatures affect human health. There have been more deaths due to heat waves and more allergy attacks as the pollen season grows longer. There have also
been some changes in the ranges of animals that carry disease like mosquitoes.
Seawater is becoming more acidic. Carbon dioxide dissolving into the oceans, is making seawater more acidic. There could be impacts on coral reefs and other marine life.
Deforestation and degradation. In the tropical regions, forests are particularly degraded as a result of anthropogenic activities. This has led to less carbon sequestrations.
Consequently, there is a major challenge to reduced emissions from deforestation and degradation (REDD).
Ecosystems are changing. As temperatures warm, species – whether in terrestrial or aquatic ecosystems – may either move to a cooler habitat or die. Species that are
particularly vulnerable include endangered species, coral reefs, and polar animals. Warming has also caused changes in the timing of spring events and the length of the