Ramsar COP8 DOC. 40:
|"Wetlands: water, life, and culture" |
8th Meeting of the Conference of the Contracting Parties
to the Convention on Wetlands (Ramsar, Iran, 1971)
Valencia, Spain, 18-26 November 2002
Ramsar COP8 DOC. 40
Unedited information paper
Interim Executive Summary to Ramsar COP8 DOC. 11:
Climate Change and Wetlands
Note: This Interim Executive Summary had been prepared by members of the Scientific and Technical Review Group's Expert Working Group on Climate Change. It was written after the finalisation of the Third Assesment Report of the Intergovernmental Panel on Climate Change (IPCC) Working Group 2: Impacts, Adaptation and Vulnerability, but prior to the finalisation of the IPCC Synthesis Report and the IPCC Technical Paper on Climate Change and Biodiversity.
Ten questions were developed by the 10th meeting of the STRP for summarizing the importance of wetlands, the impacts of climate change on wetlands, potential adaptation options and the role wetlands can play in mitigation of climate change. This Interim Executive Summary addresses these questions; underlying scientific and technical details are provided in COP8 DOC. 11.
1. What are the goods and services that wetlands provide?
Wetlands provide goods and services essential for the survival of humans. Goods and services that wetlands, like many ecosystems provide are: food, fibre (wood, reed thatching), clean water, clean air, carbon and other nutrient stores/sinks, flood and storm control, ground water recharge and discharge, pollution control, organic matter or sediment export, biodiversity, pollination, routes for animal and plant migration, landscape and waterscape connectivity, aesthetic/spiritual, cultural and recreational services (see Figure 1). These all contribute to human health and well-being.
2. What is the role of wetlands in the global biogeochemical cycles and how do human activities affect this role?
Terrestrial wetlands have a major role in the carbon, nitrogen and sulphur cycle. All these cycles are driven by the hydrological (or water) cycle. Since the 1750s, human activities, e.g., burning fossil fuel and land use land cover change, have increased the atmospheric concentrations of greenhouse gases (e.g., water vapour, carbon dioxide, methane, nitrous oxides) and thus affected all these cycles. Increase in greenhouse gases has and will continue to increase the mean surface global temperature and enhance the global hydrological cycle resulting in more extreme and heavier precipitation events in many areas with increasing precipitation. Atmospheric concentrations of carbon dioxide have increased by about 30% and methane by about 150%. Nitrogen production due to chemical fertiliser production, has doubled in the 20th century and atmospheric concentrations of nitrous oxide have increased by about 16%. Sulphur dioxide emissions, which have a cooling on the atmosphere and are generally short lived, have increased. In the late 1990s, the anthropogenic sulphur dioxide emissions have decreased due to structural changes in the energy system as well as concerns about local and regional air pollution.
The concentration of CO2 in the atmosphere along with nitrous oxide has acted as a fertiliser and has affected the uptake of carbon by some terrestrial ecosystems (including wetlands). Peat accumulating wetlands are especially important in the carbon cycle because of the large carbon store accumulated in them over millennia. With projected climate changes and the land use land cover change these stores are at risk of being released to the atmosphere. Besides being carbon sinks, wetlands are sources of methane to the atmosphere. Most wetlands are highly sensitive to hydrological changes especially at the catchment level and thus changes in hydrology (e.g., through drainage, fires, climate change) could lead to further changes in the carbon stores.
3. What are the key biophysical and socio-economic impacts of climate change on wetlands?
Climate change can directly or indirectly affect many ecosystem functions and thus the goods and services they can provide (see Figure 1). Some of these impacts are:
· a potential for significant disruption of ecosystems affecting many of their functions, e.g. productivity and decomposition
· increasing CO2 concentrations in the atmosphere could increase net primary productivity and net ecosystem productivity in vegetation systems, causing carbon to accumulate in vegetation over time
· increased risk of extinction of vulnerable species for very minimal changes in climate (e.g., 1-3oC additional warming in high latitude/altitude wetlands)
· largest and earliest impacts induced by climate change, particularly where changes in weather-related disturbance regimes and nutrient cycling are primary controls on productivity
· reduced average annual surface water runoff in some areas and increased annual runoff in others would affect many ecosystem functions. In snowmelt dominated watersheds, earlier snowmelt and a smaller proportion of winter precipitation falling as snow is projected to shift peak river flows toward winter from spring and may intensify peak flows thus changing the phenology of many species
· climatic change and other pressures making inland waters that are small and/or downstream from many human activities vulnerable
· peatlands underlain by permafrost could become net carbon sources rather than sinks. With climate warming drainage of tropical peatlands could lead to increased risk of fires and affect the viability of tropical wetlands
Examples of projected changes due to sea level rise and climate change include:
· many coastal systems will experience increased levels of inundation and storm flooding, accelerated coastal erosion, seawater intrusion into fresh groundwater, encroachment of tidal waters into estuaries and river systems, elevated sea surface temperatures and ground temperatures prevailing wave activity and storm waves and surges.
· sea level rise of about a half-meter would inundate significant portions of some small, low lying islands and their coastal ecosystems. Resources critical to island societies and economies such as freshwater, fisheries, coral reefs and atolls, beaches, and wildlife habitat would be adversely impacted
· adverse impacts on coral reefs through increased bleaching and reduced calcification rates due to higher carbon dioxide levels and increased sea water temperatures
· traditional indigenous societies in coastal areas and/or small islands are vulnerable due to their dependence on climate sensitive resources for subsistence hunting and gathering and sometimes low capacity to adapt to changes in the productivity, abundance or geographic distribution of these resources
· a number of marine mammal and bird species may be adversely affected as they are dependent on coastal fish that are sensitive to inter-annual and longer-term variability in oceanographic and climatic parameters
· migratory bird populations that rely on suitable foraging habitat whilst en-route and or those dependent on coastal sites for nesting may be adversely affected by climate change.
Extreme climatic events have and would continue to have major impacts on wetlands. Examples include:
· projected higher maximum temperatures, more hot days and heat waves could lead to increased heat stress and increased susceptibility to pest and disease attack in many wetland plants and animals
· projected increased summer drying over most mid-latitude continental interiors and associated risk of drought could lead to decreased water resource quantity and quality, physiological stress on animals and plants, decreased wetland productivity in some areas and increased risk of fires.
Impacts of potential changes in wetlands on climate change include:
· in the Arctic, changes in forests/grassland/shrubland/wetland extent and boundaries could enhance projected regional warming
· in areas without surface water (typically semi-arid or arid), evapotranspiration and the albedo affect the local hydrologic cycle and thus a reduction in vegetative cover could lead to reduced precipitation at local/regional scale and change the frequency and persistence of droughts.
Human responses to climate change could further exacerbate the negative impact on many wetlands. For example, human responses to a warmer climate are likely to place greater demands on freshwaters to meet water needs for urban and agricultural use. This could potentially result in decreased flow in rivers and streams and/or decrease in free flowing rivers/streams and greater fluctuations in water level. These changes would cause a loss of ecosystem services and products from some wetlands. Conflicts between developers and those wishing to reduce the development pressure on lakes and streams would likely intensify as freshwater becomes either more scarce or more abundant.
4. Do these impacts differ between types of wetlands and between regions?
Like any ecosystems, some wetlands can be considered to be resilient to climate change and others more sensitive either because they are near their moisture or temperature tolerance and/or because the species and the function have very narrow temperature and moisture limits. Broadly speaking, wetlands can be classified into those with
a) permanent wetlands (e.g., lakes, rivers, reefs),
b) broad short-term variability (i.e., high intra-annual variation, e.g. between wet and dry season, or high and low tide) and
c) ephemeral wetlands that have high interdecadal or interannual variability (e.g., those in arid and semi-arid parts of the world).
Impacts of climate change would thus vary between these wetland types. In addition, there is an effect of inertia in many wetland ecosystems, e.g. due to the longevity of the species, which means that the impacts may not become apparent over a short time period. Wetlands in high latitude and/or high latitude areas and coral reefs are considered to be amongst those most sensitive to climate change and thus are likely to be impacted earliest. The others that could be impacted by climate change are those in regions that experience El Niño-like phenomena which are projected to increase in intensity and frequency and/or are located in the continental interiors and thus are likely to experience changes in the catchment hydrology. In the near-shore marine and coastal systems, many wetlands could be impacted indirectly as a result of climate change due to changes in storm surges and saltwater intrusion into the freshwater systems.
5. What is the effect of climate change relative to the other pressures affecting wetlands?
The earth is being subjected to many human induced and natural changes, often referred to as global change. These include pressures from increased demand for resources, increase in human consumption patterns leading to land-use and land-cover change (including urbanisation), accelerated rate of anthropogenic nitrogen production/deposition and other air pollutants, accelerated rate of biodiversity loss and climate change (see Figure 1). The impacts of these pressures often lead to increased demand for access to land, water and wildlife resources. The result is a change in the state of the earth's land surface and in the landscapes where humans live and the goods and services humans receive from the ecosystems, at regional and global scales. The impacts of climate change include changes in atmospheric composition of greenhouse gases (e.g., water vapour, carbon dioxide, and nitrous oxides), temperature, precipitation and sea level rise. These can then affect disturbance regimes, such as frequencies of fires and outbreaks of pest/diseases.
Over the next two or three decades, the land use land cover change resulting in drainage and clearance of wetlands, changes in their hydrology, are likely to dominate the changes due to projected climate change. However, the changes listed above interact with each other and affect the ecosystem functions (e.g., primary and secondary production, decomposition etc). For wetlands in particular, climate change is an added stress that would affect the hydrological regime, the biodiversity and thus many of the functions and thus the goods and services provided by these ecosystems. Climate change on its own and/or in combination with the other pressures is thus likely to become more important especially if the greenhouse gas emissions and thus the temperature projections are at the higher end of the Intergovernmental Panel on Climate Change assessments over the 2030 onwards time frames.
Figure 1: Climate change in the context of global change and the interaction between these changes, their drivers (socio-economic pathways), the ecosystem functions and the goods and services that ecosystems provide. Modified from IPCC (2001c) and Gitay et al (2001)
6. What options exist to adapt to climate change and which of these options complement or conflict with Ramsar's Guidelines for the wise use of wetlands?
Adaptation in IPCC is taken to be a human intervention with the intent of lessening the effects of climate change and not the autonomous response of the ecosystems (e.g., increased net primary productivity in many species due to the increased levels of atmospheric concentrations on carbon dioxide). Adaptation options can thus be dependent on institutional capacity and infrastructure in the region or country. In general, the potential for adaptation is more limited for developing countries, which are also projected to be the more adversely affected by climate change. Adaptation appears to be easier if the climate changes are modest and/or gradual rather than large and/or abrupt. Many of the adaptation options can not only address climate change impacts but could provide "win-win" option for other problems, e.g. wetland degradation..
Adaptation options should be considered in the sustainable development framework and thus are not likely to conflict with the wise use of wetlands. However, given the inertia in some wetland species and function, developing adaptation options would have to take these into account. In addition, there is also likely to be institutional inertia, e.g. implementation of management plans may be in a 10-year cycle, and thus these could affect the planning and implementation of adaptation options. Monitoring of adaptation options should be considered to be an essential feature so that the overall adaptive framework that is responsive to the changes being observed either as a result of the adaptation measures or some other factors can be modified.
Most of the wetland processes are dependent on the catchment level hydrology. Thus, adaptations for the projected climate change may be practically impossible or very limited. Potential adaptation options are also limited due to the geomorphology of the system so that the evolutionary time frame the dynamics of the system can limit some options. For example, a coastal low-lying wetland system that is relatively young and has dynamic substrate and channelling system has fewer adaptation options than an older and more stable system.
Nevertheless there are a number of potential adaptation options that can contribute to the conservation and sustainable use of wetlands. Examples include:
· designing multiple-use reserves and protected area which incorporate corridors that would allow for migration or organism as a response to climate change. The response of some wetland species (both animals and plants) to climate change could be a range expansion or poleward movement of the species. Some of these may be invasive species (both native and exotics) and could impact on the system especially through changes in the hydrology. Adaptation option in this case would have to include truncation of potential corridors or control of invasive species to limit the expansion of more competitive native or exotic species especially into wetlands that may be small and have high endemism.
· expanding aquaculture to relieve stress on natural fisheries
· specific management in some ecosystems could reduce pressures on wetlands, e.g., in the wetlands in the Arctic, economic diversification could reduce the pressure on wildlife, rotational and decreased use of marginal wetlands especially in semi-arid areas could reduce wetland and wetland biodiversity loss
· integrated land, water and marine area management with the aim of reducing non-climate stresses could be beneficial to wetlands, e.g., reduction of fragmentation of water systems, reduction of land-based pollution into marine systems such as coral reefs
· others that could benefit wetlands include: efficient use of natural resources and restoration of degraded wetlands.
There are likely to be negative repercussions of specific adaptation options. Examples include:
· active transportation of aquatic species or "better-adapted" warm water species poleward which from historical evidence would suggest could result in the extinction of local wetland species and large changes in ecosystem processes and structure all with economic consequences
· interactions resulting from increased stocking and relocation of recreational and aquaculture endeavours
· other negative effects related to secondary pressures from new hydrologic engineering structures.
8. Are there some ecosystem types that could be considered to be particularly vulnerable?
Human and natural systems are defined to be vulnerable to climate change either because they have few or no adaptation options to reduce the impacts of climate change and/or they are naturally sensitive to climate change (for example due to their geographic or socio-political location). Due to limited or lack of adaptation options for wetlands and or the sensitivity to climate change, some wetlands can be considered to be vulnerable to climate change.
High latitude and high altitude wetlands, e.g. in the Arctic and sub-arctic ombotrophic bog communities, alpine streams and lakes, coral reefs, coastal freshwater wetlands and freshwater lenses that are susceptible to salt water intrusion are considered to be vulnerable to climate change. Wetlands that are affected by one or more of the pressures of global change (see figure 1) and/or introduction or invasion by exotic species are also considered to be vulnerable to climate change. Potential changes in quantity and quality of water reduce the ability of these wetlands to provide and continue to provide many of the goods and services.
9. What options exist to use wetlands in mitigating greenhouse gas emissions and which of these complement or conflict with Ramsar guidelines on the wise use of wetlands?
Human activities, e.g. fossil fuel use, land use land cover change, have resulted in increase in the amounts of carbon being added to the atmosphere. About 28% of the carbon since the 18th century has been retained in the atmosphere and the remainder is estimated to have been taken up, in approximately equal amounts, by oceans and the terrestrial ecosystems. Between 1980 and 1998, the terrestrial ecosystems have been a small net sink for carbon dioxide probably as a result of land use practices and natural regrowth, the indirect effects of human activities, including the CO2 fertilisation effect and nitrogen deposition and possibly changing climate. Projections suggest that the additional terrestrial uptake of atmospheric CO2 on a global scale may continue for a number of decades but may then gradually diminish and could even become a source by the end of the 21st century. This conclusion does not consider the effect of future land use and land cover change or actions to enhance the terrestrial carbon sinks. In particular the Kyoto Protocol and the Bonn Accord allows carbon credits for afforestation, reforestation and avoided deforestation activities. Both of these are likely to affect wetlands as afforestation could allow forested wetlands on land that has been without forest cover for a period if time (eg. 20 to 50 years) and reforestation - the conversion of non-forested land to forest land, with the land being under a different land use over historical times. However, these actions may be minimal for forested wetlands. Nevertheless, these actions can have benefits to the wetlands but can also pose risks. Consistency with national and/or international sustainable development goals could reduce the risk of the negative impacts. Impacts include:
· reforestation or afforestation activity benefits could include an increase in the diversity of flora and fauna, except in cases where biologically diverse non-forested ecosystems (e.g., grasslands) are replaced by forests consisting of single or few species. These negative impacts could be minimised by measures that lengthen rotations, maintain understory vegetation, use native tree species and minimise chemical inputs. Afforestation can have varied impacts on ecosystem functions, such as water run-off and nutrient cycling.
· avoiding deforestation can provide potentially large co-benefits, including conservation of biodiversity, soil resources and maintenance of non-timber forest products.
· increasing tree cover or protecting it from being decreased can improve and protect soil quality in areas that are vulnerable, e.g. stabilise watershed flows thus potentially indirectly benefit wetland fucntions.
· One of the major sources of greenhouse gases is from peatland dominated wetlands (as methane and CO2). Actions that would avoid degradation of these wetlands and thus the potential release of the greenhouse gases would be an beneficial mitigation option.
10. What are the robust conclusions and key uncertainties?
There is still lack of detailed information about the distribution, extent and use of wetlands which makes it difficult to predict the impacts of climate change. Lack of consistent classification exacerbates the problem. In addition, changes in wetlands are dominated by changes in catchment hydrology.
Climate change has already affected some wetlands (e.g. Arctic wetlands, coral reefs) and will continue to do so. Lack of regional specific wetland data, regional climate change scenarios let alone catchment level climate change scenarios, makes it difficult to predict that the impacts of climate change on many wetlands.
Many pressures (e.g., land use change, pollution, extraction of water for urban or agricultural use) act on the wetlands simultaneously, but may be with different time lags (eg. the run-of changes due to deforestation can be slow compared with those due to local temperature changes due to changes in the frequency and intensity of El Niño-like phenomena). These add to the problems of looking at the impacts but also the adaptation options. Increase in the additional pressures due to human activity (e.g., drainage of wetlands or changes in their uses, including introduction of exotic species for recreational purposes) is likely to increase the impacts and limit the adaptation options. The overall adaptation options would be to minimise changes in hydrological regimes. Adaptation is no longer an option; it is a necessity, given that climate change-related impacts are already occurring. Adaptation options will vary with location and wetland types but have the potential to reduce many of the adverse impacts of climate change and to enhance beneficial impacts. The capacity of different regions to adapt to climate change depends highly upon their current and future states of socio-economic development and their exposure to climate stress. Therefore the potential for adaptation is more limited for developing countries, which are projected to be the most adversely affected. Adaptation appears to be easier if the climate changes are modest and/or gradual rather than large and/or abrupt.
A major component of adaptation that needs further attention is assessment of the vulnerability of wetlands to climate change and sea level rise. Many wetlands are vulnerable to climate change either due to their sensitivity to changes in moisture and temperature regimes and or due to the other pressures from human activities and limited or lack of adaptation options. Future management for these wetlands would have to take the multiple pressures and the added stress of climate change into account. Monitoring program to look at the effectiveness of these adaptation or management options and steps to rectify any adverse effects should be part of the adaptive management strategy. There is a danger of implementing adaptation options that have local or short term benefits (e.g., fish stock for recreational fishing in a warming lake, infrastructure development to control floods) but could result in longer term negative consequences (e.g., extinction of local species and thus loss in local biodiversity and more damage from a large flood as there was limited route for water to flow).
Some uncertainties arise from a lack of data and a lack of understanding of key processes and from disagreement about what is known or even knowable. Other uncertainties are associated with predicting social and personal behaviour in response to information and events. The uncertainties tend to escalate with the complexity of the problem (eg. changes due to the multiple pressures), but also due to elements being introduced to include a more comprehensive range of physical, technical, social, and political impacts and policy responses. The uncertainties can never be fully resolved, but often they can be bounded by more evidence and understanding, particularly in the search for consistent outcomes or robust conclusions.
Our understanding of wetland hydrology, its effects on chemical and biological functions is very limited and thus is a key uncertainty to the predicting any impacts due to any of the single and or multiple pressures due to human activities and developing adaptation options. The feedbacks, lag times and the inertia in the response of wetlands and their functions adds to the uncertainties. Many of the wetlands require detailed local knowledge both in terms of understanding the processes, the distribution of the wetlands, their uses and the past and present management. This in many regions is lacking or very limited. Thus it is hard to project the impacts of climate change for many regions beyond a generic level, let alone suggest adaptation options.