Climate Change – Impacts on Biodiversity and Ecosystems

This page is a Technical Paper of the Intergovernmental Panel on Climate Change (IPCC) and was prepared under the auspices of the IPCC Chair, Dr. Robert T.Watson. I have developed this page around this technical paper in the hope that our readers will find some really useful and important stuff to know about our changing climate and to understand the need to take actions to prevent further environmental degradation.

Definition of Biodiversity

Biodiversity is “the variability among living organisms from all sources including, inter alia, terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems.” IPCC also emphasizes these three levels—that is, genetic, species, and ecosystem.

This paper also considers biodiversity that occurs in both intensively (agriculture, plantation forestry, and aquaculture) and non-intensively (e.g., pastoral lands, native forests, freshwater ecosystems, and oceans) managed ecosystems. It also recognizes the intrinsic value of biodiversity, irrespective of human needs and interests.

Ecosystems provide many goods and services that are crucial to human survival. Some indigenous and rural communities are particularly dependent on many of these goods and services for their livelihoods. These goods and services include food, fiber, fuel and energy, fodder, medicines, clean water, clean air, flood/ storm control, pollination, seed dispersal, pest and disease control, soil formation and maintenance, biodiversity, cultural, spiritual, and aesthetic and recreational values. Ecosystems also play a critical role in biogeochemical processes that underlie the functioning of the Earth’s systems.

Climate Change and Biodiversity

At the global level, human activities have caused and will continue to cause a loss in biodiversity through, inter alia, land-use and land-cover change; soil and water pollution and degradation (including desertification), and air pollution; diversion of water to intensively managed ecosystems and urban systems; habitat fragmentation; selective exploitation of species; the introduction of non-native species; and stratospheric ozone depletion.

The current rate of biodiversity loss is greater than the natural background rate of extinction. Changes in climate exert additional pressure and have already begun to affect biodiversity. The atmospheric concentrations of greenhouse gases have increased since the pre-industrial era due to human activities, primarily the combustion of fossil fuels and land-use and land-cover change.

Climate change is projected to affect all aspects of biodiversity; however, the projected changes have to take into account the impacts from other past, present, and future human activities, including increasing atmospheric concentrations of carbon dioxide (CO2). Changes in biodiversity at ecosystem and landscape scale, in response to climate change and other pressures (e.g., changes in forest fires and deforestation), would further affect global and regional climate.

The SRES Scenarios of Climate Change

A1: The A1 storyline and scenario family describe a future world of very rapid economic growth, global population that peaks in mid-century and declines thereafter, and the rapid introduction of new and more efficient technologies. Major underlying themes are convergence among regions, capacity building, and increased cultural and social interactions, with a substantial reduction in regional differences in per capita income. The A1 scenario family develops into three groups that describe alternative directions of technological change in the energy system. The three A1 groups are distinguished by their technological emphasis: fossil-intensive (A1FI), non-fossil energy sources (A1T), or a balance across all sources (A1B)-where balanced is defined as not relying too heavily on one particular energy source, on the assumption that similar improvement rates apply to all energy supply and end use technologies.

A2: The A2 storyline and scenario family describe a very heterogeneous world. The underlying theme is self-reliance and preservation of local identities. Fertility patterns across regions converge very slowly, which results in continuously increasing population. Economic development is primarily regionally oriented and per capita economic growth and technological change more fragmented and slower than other storylines.

B1: The B1 storyline and scenario family describe a convergent world with the same global population, which peaks in mid-century and declines thereafter, as in the A1 storyline but with rapid change in economic structures toward a service and information economy, with reductions in material intensity and the introduction of clean and resource-efficient technologies. The emphasis is on global solutions to economic, social, and environmental sustainability, including improved equity, but without additional climate initiatives.

B2: The B2 storyline and scenario family describe a world in which the emphasis is on local solutions to economic, social, and environmental sustainability. It is a world with continuously increasing global population at a rate lower than A2, intermediate levels of economic development, and less rapid and more diverse technological change than in the B1 and A1 storylines. While the scenario is also oriented towards environmental protection and social equity, it focuses on local and regional levels.

Climate Change and Ecosystems

Climate is the major factor controlling the global patterns of vegetation structure, productivity, and plant and animal species composition. Many plants can successfully reproduce and grow only within a specific range of temperatures and respond to specific amounts and seasonal patterns of precipitation, and may be displaced by competition from other plants or may fail to survive if climate changes. Animals also have distinct temperature and/or precipitation ranges and are also dependent on the ongoing persistence of their food species.

Changes in mean, extremes, and climate variability determine the impacts of climate change on ecosystems. Climate variability and extremes can also interact with other pressures from human activities. For example, the extent and persistence of fires – such as those along the edges of peat-swamp forests in southern Sumatra, Kalimantan, and Brazil during recent El Niño events - show the importance of the interaction between climate and human actions in determining the structure and composition of forests and land-use patterns.

Productivity and Associated Terms

Productivity can be measured in several ways, including net primary productivity (NPP), net ecosystem productivity (NEP), and net biome productivity (NBP). Plants are responsible for the vast majority of uptake of carbon by terrestrial ecosystems. Most of this carbon is returned to the atmosphere via a series of processes including respiration, consumption (followed by animal and microbial respiration), combustion (e.g., fires), and chemical oxidation.

Gross primary productivity (GPP) is the total uptake through photosynthesis whereas NPP is the rate of accumulation of carbon after losses due to plant respiration and other metabolic processes in maintaining the plant’s living systems are taken into account. The consumption of plant material by animals, fungi, and bacteria (heterotrophic respiration) returns carbon to the atmosphere and the rate of accumulation of carbon over a whole ecosystem and over a whole season (or other period of time) is NEP. In a given ecosystem, NEP is positive in most years and carbon accumulates even if only slowly. However, major disturbances such as fires or extreme events that cause the death of many components of the biota release greater than usual amounts of carbon.

Impacts of Climate Change in Africa

Projected impacts of climate change in Africa include:

Many thousands of plants are potentially affected by climate change, particularly the floristically diverse fynbos and Karoo, both of which occur in winter rainfall regions at the southern tip of the continent, and are threatened particularly by a shift in rainfall seasonality (e.g., a reduction in winter rainfall amounts or an increase in summer rainfall, which would alter the fire regime critical to regeneration in the fynbos).
Projected changes in climate during the 21st century could alter the distribution of antelope species.
Major rivers are highly sensitive to climate variation; average runoff and water availability is projected to decrease in Mediterranean and southern countries of Africa, which would affect their biodiversity.
There are several globally important wetland areas in Africa (e.g., Okavanga Delta). Decreases in runoff could lead to a reduction in area of these resources.
Extension of ranges of infectious disease vectors could occur and affect some wildlife species. Phenology of insect pests and diseases is projected to change, potentially resulting in increased agricultural and forestry losses, as well as unknown consequences in many ecosystems.
Increases in droughts, floods, and other extreme events would add to stresses on many ecosystems.
Desertification would be exacerbated by reductions in average annual rainfall or increases in average evaporative demand; either or both would lead to reduced runoff and soil moisture, especially in southern, north, and west Africa .
At particular risk of major biodiversity loss are plants and animals that have limited mobility and occur in reserves on flat and extensive landscapes, areas where rainfall regime may change seasonality (e.g., the southern Cape), where tree/grass balance are sensitive to CO2 conditions and/or climatic factors, and where fire/other disturbance regime could change.
Ecosystems that are particularly vulnerable to climate change include fynbos, some rangelands (including the Karoo), cloud/montane forests, and wetlands (especially riparian) in arid/semi-arid areas.
Significant local and global extinctions of plant and animal species, many of which are an important resource for African people, are projected and would impact rural livelihoods, tourism, and genetic resources.

Impacts of Climate Change in Asia

Projected impacts of climate change in Asia include:

Species in high-elevation ecosystems are projected to shift higher. In the higher elevated areas, the rates of vegetation change are expected to be slow, and colonization success would be constrained by increased erosion and overland flows such as in the highly dissected and steep terrains of the Himalayan mountain range; weedy/invasive species with a wide ecological tolerance will have an advantage over others.
There may be a decline of conifer forests in northeast China and broad-leaved forests in east China may shift northward by up to several hundred kilometers. Frequency and intensity of forest fires and pest outbreaks in the boreal forests are likely to increase.
Deltaic coastal ecosystems in China could be detrimentally affected by sea-level rise. Sea-level rise could cause large-scale inundation of freshwater wetlands along the coastline and recession/loss of flat coastal habitats.
With projected increases in temperature and decreases in precipitation, water quality might deteriorate and eutrophication might be exacerbated (e.g., in some lakes in Japan).
Mangroves (e.g., those in the Sundarbans) and coral reefs are particularly vulnerable due to climate change. The Sundarbans supports a diversity of wildlife and is at great risk due to rising sea level. With a 1m rise in sea level, the Sundarbans will disappear, which will spell the demise of the Bengal tiger and other wildlife, and could adversely affect local human populations.
With the projected decrease in productivity (of 40 to 90%), climate change is likely to represent an additional stress on rangelands and affect many people’s livelihoods. Both climate change and human activities will further influence the levels of the Caspian and Aral Seas with implications for biodiversity and the people.

Impacts of Climate Change in Australia and New Zealand

Projected impacts of climate change in Australia and New Zealand include:

Projected drying trends over much of the region and change to a more El Niño-like average state is likely to affect many ecosystems, especially semi-arid ones.
Increases in the intensity of heavy precipitation events and region-specific changes in the frequency of tropical cyclones would affect ecosystems due to flooding, storm surges, and wind damage.
Although many species will be able to adapt, climate change is expected to reduce the overall biodiversity in individual ecosystems.
Changes in forest and woodland composition due to climate change are most likely to occur where fragmentation of the forest and woodland reduces the potential for migration of new, more suitable species.
Ecosystems that are particularly vulnerable to climate change include coral reefs, arid and semi-arid habitats in southwest and inland Australia, freshwater wetlands in the coastal zone, and alpine systems.
Some New Zealand ecosystems would become vulnerable to invasive species.

Impacts of Climate Change in Europe

Projected impacts of climate change in Europe include:

Ecosystems are projected to change in composition, structure, and function with poleward and upward range extension of some species: Permafrost will decline; trees and shrubs will extend into northern tundra; and broad-leaved trees may encroach coniferous forests.
Most climate change scenarios suggest a possible overall northward displacement of the climatic zone that is suitable for boreal forests by several hundred of kilometers by the year 2100.
In mountain regions, higher temperatures will lead to an upward shift of biotic and cryospheric zones and perturb the hydrological cycle. As a result of a longer growing season and higher temperatures, European alpine areas will shrink because of upward migration of tree species.
Flood hazard will increase across much of Europe; risk would be substantial for coastal areas where flooding will increase erosion and result in loss of coastal wetlands. Estimated coastal wetland losses by the 2080s range from 0–17% for the Atlantic coast, through 84–98% for the Baltic coast, to 81–100% for the Mediterranean coast, and any surviving wetlands may be substantially altered.
Loss of important habitats (wetlands, tundra, isolated habitats) would threaten some species, including rare/endemic species and migratory birds. Snowmelt-dominated watersheds will experience earlier spring peak flows and possible reductions in summer flows and water levels in streams and lakes. This will impact aquatic ecosystems.
Plant species richness can decline in areas with Mediterranean-type ecosystems if climate becomes more arid.
Higher winter temperatures could increase the distribution range of some introduced species (e.g., Nothofagus procera in Britain).
Where ranges of species are already fragmented they may become even more fragmented, with regional disappearances of species, if they cannot persist, adapt, or migrate.
With climate change, valued communities within protected areas may dissociate, leaving species with nowhere to go. Particular species populations in sites that lie near their current maximum temperature limits could be expected to become extinct if climate warms beyond these limits. As a result of climate change, nature reserve communities may lose species at a faster rate than potential new species can colonize, leading to a long period of impoverishment for many reserves.

Impacts of Climate Change in Latin America

Projected impacts of climate change in Latin America include:

Increase in the rate of biodiversity loss.
Adverse impacts on cloud (mist) forests, tropical seasonally dry (deciduous) forests and shrublands, low-lying habitats (coral reefs and mangroves), and inland wetlands.
Loss and retreat of glaciers would adversely impact runoff and water supply in areas where glacier melt is an important water source, thus affecting the seasonality of systems like Paramos lagoons that are rich in biodiversity.
More frequent floods and droughts, with floods increasing sediment loads and causing degradation of water quality in some areas.
Mangrove ecosystems will be degraded or lost by sea-level rise at a rate of 1–1.7% per year and will lead to decline in some fish species.
Climate change could disrupt lifestyles in mountain villages by altering already marginal food production and the availability of water resources and the habitats of many species that are important for indigenous peoples.
Climate change might have some beneficial effects on freshwater fisheries and aquaculture, although there could be some significant negative effects, depending on the species and on the specific climate changes at the local level.

Impacts of Climate Change in North America

Projected impacts of climate change in North America include:

Snowmelt-dominated watersheds in western North America could experience earlier spring peak flows and possible reductions in summer flows leading to possible aquatic ecosystem impacts.
Geographic ranges of species are expected to continue to shift northward and upward in altitude, but many species cannot move across the land surface as rapidly as climate is projected to change and/or there may be barriers to range shifts. The faster the rate of climate change, the greater the probability of ecosystem disruption and species extinction.
Increased temperatures could reduce subarctic ecosystems. Loss of migratory wildfowl and mammal breeding and forage habitats may occur within the taiga/tundra, which is projected to nearly disappear from mainland areas.
Sea-level rise and increased frequency of storm surges would result in enhanced coastal erosion, coastal flooding, and loss of coastal wetlands, particularly in Louisiana, Florida, and much of the U.S. Atlantic coast. Approximately 50% of North American coastal wetlands could be inundated.
El Niño events are linked to declines of fisheries off the west coast of North America and feeding areas for salmon may become less productive, potentially leading to reduced catches.
Stream fish habitats are projected to decline across the United States by 47% for cold water, 50% for cool water, and 14% for warm water species.
Unique non-intensively managed ecosystems such as tundra, some coastal salt marshes, prairie wetlands, arid and semi-arid landscapes, and cold water ecosystems are vulnerable and effective adaptation is unlikely.
Climate change may cause changes in the nature and extent of several disturbance factors (e.g., fire, insect outbreaks) in forested areas. Climate change also appears to be accelerating the seasonal development of some insect species. Changes in ranges and/or outbreak frequency have been projected for a number of injurious insect pests. These changes could lead to changes in the underlying structure and species composition of some forested areas with possible concomitant changes to biodiversity.
Invasive species are expected to increase and increase the vulnerability of existing ecosystems.

Impacts of Climate Change in Small Island States

Projected impacts of climate change in Small Island States include:

Coral reefs will be negatively affected by bleaching and by reduced calcification rates which can lead to the loss of many reef-associated communities and species.
Mangrove, sea grass beds, other coastal ecosystems, and the associated biodiversity would be adversely affected by rising temperatures and accelerated sea-level rise.
Saltwater intrusion into freshwater habitats will affect their biodiversity.
Increases in typhoon/hurricane frequency or wind speed could negatively impact some habitats.
Inundation and flooding of low-lying forested areas in islands will lead to the loss of some endemic bird species, as the majority of threatened bird species are found in forested habitats. Impacts of climate change on these species are likely to be due to direct physiological stress and changes/loss in habitat caused by changes in disturbance regimes, such as fires.
A rise in sea level will have a serious impact on atoll agroforestry and the pit cultivation of taro which are important for many island communities. Erosional changes in the shoreline will disrupt populations, and the combined effects of freshwater loss and increased storm surges will stress freshwater plants and increase vulnerability to drought.

One Response to Climate Change – Impacts on Biodiversity and Ecosystems

waste to energy

Hi, I have read this article and I learned alot all about our climate change. Thanks for sharing this informative and helpful article. God bless.

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