Issue Position: Climate Change Effects

Issue Position

Studies of the climate range of species indicate that between 15 and 37% of all species will be faced with extinction in the near future because of climate change alone. However, these estimates do not include the effects of interspecies dependency. "Top consumers" in an environment are especially vulnerable to climate change, and their removal can ripple through the entire food web, increasing extinction risk along the way. (Source: Zarnetske et al., Science Vol.336 pp. 1516-1518, 2012)

The table below gives examples of expected effects of climate change. However, it does not describe the expected consequences of these effects. Warming of, say, 5 °F will cause dramatic changes in water availability, ecosystems, agricultural productivity, disaster risk, and sea level. These changes will require resettlement programs unlike anything we have experienced in recorded history. Climate-related resettlement is already underway in Vietnam in the Mekong River Delta, in Mozambique along the Limpopo River, in Inner Mongolia, and from the Carteret Islands to Bougainville Island. (Source: Sherbinin et al., Science Vol.334 pp. 456-457, 2011)

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Africa

-By 2020, between 75 and 250 million of people are projected to be exposed to increased water stress due to climate change.
-By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%. Agricultural production, including access to food, in many African countries is projected to be severely compromised. This would further adversely affect food security and exacerbate malnutrition.
-Towards the end of the 21st century, projected sea level rise will affect low-lying coastal areas with large populations. The cost of adaptation could amount to at least 5 to 10% of Gross Domestic Product (GDP).scenarios (TS).
-By 2080, an increase of 5 to 8% of arid and semi-arid land in Africa is projected under a range of climate

Asia

-By the 2050s, freshwater availability in Central, South,East and South-East Asia, particularly in large river basins, is projected to decrease.
-Coastal areas, especially heavily populated megadelta regions in South, East and South--East Asia, will be at greatest risk due to increased flooding from the sea and, in some megadeltas, flooding from the rivers.
-Climate change is projected to compound the pressures on natural resources and the environment associated with rapid urbanization, industrialization and economic development.
-Endemic morbidity and mortality due to diarrheal disease primarily associated with floods and droughts are expected to rise in East, South and South-East Asia due to projected changes in the hydrological cycle.

Australia and New Zealand

-By 2020, significant loss of biodiversity is projected to occur in some ecologically rich sites, including the
Great Barrier Reef and Queensland Wet Tropics.
-By 2030, water security problems are projected to intensify in southern and eastern Australia and, in New Zealand, in Northland and some eastern regions.
-By 2030, production from agriculture and forestry is projected to decline over much of southern and eastern Australia, and over parts of eastern New Zealand, due to increased drought and fire. However, in New Zealand, initial benefits are projected in some other regions.
-By 2050, ongoing coastal development and population growth in some areas of Australia and New Zealand are projected to exacerbate risks from sea level rise and increases in the severity and frequency of storms and coastal flooding.

Europe

-Climate change is expected to magnify regional differences in Europe's natural resources and assets. Negative impacts will include increased risk of inland flash floods and more frequent coastal flooding and increased erosion (due to storminess and sea level rise).
-Mountainous areas will face glacier retreat, reduced snow cover and winter tourism, and extensive species losses (in some areas up to 60% under high emissions scenarios by 2080).
-In southern Europe, climate change is projected to worsen conditions (high temperatures and drought) in a region already vulnerable to climate variability, and to reduce water availability, hydropower potential, summer tourism and, in general, crop productivity.
-Climate change is also projected to increase the health risks due to heat waves and the frequency of wildfires.

Latin America

-By mid-century, increases in temperature and associated decreases in soil water are projected to lead to gradual replacement of tropical forest by savanna in eastern Amazonia. Semi-arid vegetation will tend to be replaced by arid-land vegetation.
-There is a risk of significant biodiversity loss through species extinction in many areas of tropical Latin America.
-Productivity of some important crops is projected to decrease and livestock productivity to decline, with adverse consequences for food security. In temperate zones, soybean yields are projected to increase. Overall, the number of people at risk of hunger is projected to increase (TS; medium confidence).
-Changes in precipitation patterns and the disappearance of glaciers are projected to significantly affect water availability for human consumption, agriculture and energy generation.

North America

-Warming in western mountains is projected to cause decreased snowpack, more winter flooding and reduced summer flows, exacerbating competition for over-allocated water resources.
-In the early decades of the century, moderate climate change is projected to increase aggregate yields of rain-fed agriculture by 5 to 20%, but with important variability among regions. Major challenges are projected for crops that are near the warm end of their suitable range or which depend on highly utilized water resources.
-Cities that currently experience heat waves are expected to be further challenged by an increased number, intensity and duration of heat waves during the course of the century, with potential for adverse health impacts.
-Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution.

Polar Regions

-The main projected biophysical effects are reductions in thickness and extent of glaciers, ice sheets and sea ice, and changes in natural ecosystems with detrimental effects on many organisms including migratory birds, mammals and higher predators.
-For human communities in the Arctic, impacts, particularly those resulting from changing snow and ice conditions, are projected to be mixed.
-Detrimental impacts would include those on infrastructure and traditional indigenous ways of life.
-In both polar regions, specific ecosystems and habitats are projected to be vulnerable, as climatic barriers to species invasions are lowered.

Small Islands

-Sea level rise is expected to exacerbate inundation, storm surge, erosion and other coastal hazards, thus threatening vital infrastructure, settlements and facilities that support the livelihood of island communities.
-Deterioration in coastal conditions, for example through erosion of beaches and coral bleaching, is expected to affect local resources.
-By mid-century, climate change is expected to reduce water resources in many small islands, e.g. in the Caribbean and Pacific, to the point where they become insufficient to meet demand during low-rainfall periods.
-With higher temperatures, increased invasion by non-native species is expected to occur, particularly on mid- and high-latitude islands.

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