Regional Impacts
It is more difficult to anticipate how climate change will evolve at the regional than at the global level. Nevertheless, enormous strides have been made in recent years, allowing scientists to conclude that:
Small island states — Particularly vulnerable to climate change, their limited size makes them more prone to natural hazards and external shocks, in particular to rises in sea-level and threats to their freshwater resources.
Africa — Very vulnerable to climate change and climate variability due to endemic poverty, weak institutions, and complex disasters and conflicts. Drought has spread and intensified since the 1970s, and the Sahel and southern Africa have already become drier during the 20th century. Water supplies and agricultural production will likely be severely compromised. Yields in some countries could drop by as much as 50 per cent by 2020, and some large regions of marginal agriculture are likely to be forced out of production. Forests, grasslands and other natural ecosystems are already changing, particularly in southern Africa. By the 2080s, the amount of arid and semi-arid land in Africa will likely increase by 5-8 per cent.
Antarctica — This continent has proven more difficult to understand and predict. With the exception of the rapidly warming Antarctic Peninsula, both temperatures and snowfall have remained relatively constant for the continent as a whole over the past 50 years. Because this frozen continent contains almost 90 per cent of the planet's freshwater, researchers are watching carefully for any signs that its glaciers and ice sheets may be melting.
The Arctic — Average temperatures in the Arctic have increased almost twice as fast as the global average over the past 100 years. The average extent of Arctic sea ice has been shrinking by 2.7 per cent per decade and large areas of the Arctic Ocean could lose year-round ice cover by the end of the 21st century if human emissions reach the higher end of current estimates. The Arctic is also particularly important because changes there have important global implications. For example, as ice and snow melts, the Earth’s albedo (reflectivity) is decreased, trapping heat that would otherwise be reflected and warming the earth’s surface even further.
Asia — More than a billion people could be affected by a decline in the availability of freshwater, particularly in large river basins, by 2050. Glacier melt in the Himalayas, which is projected to increase flooding and rock avalanches, will affect water resources in the next two to three decades. As glaciers recede, river flows will decrease. Coastal areas, especially heavily populated mega-delta regions, will be at greatest risk due to increased flooding from the sea and, in some cases, from river flooding.
Australia and New Zealand — Increasing stress on water supplies and agriculture, changing natural ecosystems, less seasonal snow cover and shrinking glaciers. Over the past few decades there have been more heat waves, fewer frosts and more rain in north-west Australia and south-west New Zealand; less rain in southern and eastern Australia and north-eastern New Zealand; and an increase in the intensity of Australian droughts. The climate of the 21st century is virtually certain to be warmer with more frequent and intense heat waves, fires, floods, landslides, droughts and storm surges.
Europe — Glaciers and permafrost are thawing, growing seasons are lengthening and weather extremes — such as the disastrous heat wave of 2003 — are more frequent. Researchers believe that Europe’s northern regions will experience warmer winters, greater precipitation, expanding forests and greater agricultural productivity. Southern regions near the Mediterranean will see hotter summers, less precipitation, more droughts, retreating forests and reduced agricultural productivity. Europe contains a great deal of low-lying coastland vulnerable to rises in sea-level, and many plants, reptiles, amphibians and other species are likely to become endangered by the end of the century.
Latin America — The tropical forests of eastern Amazonia and southern and central Mexico are expected to be gradually replaced by savannah. Parts of north-east Brazil and most of central and northern Mexico will become more arid due to a combination of climate change and human land management. By the 2050s, 50 per cent of agricultural lands are highly likely to be experiencing desertification and salinization.
North America — Climate change will further constrain water resources, already stretched by growing demand from agriculture, industry and cities. Rising temperatures will further diminish the mountain snow pack and increase evaporation, thus altering the seasonal availability of water. Lower water levels in the Great Lakes and major river systems will affect water quality, navigation, recreation and hydropower. Wildfire and insect outbreaks will continue to intensify in a warmer world with drier soils. Over the 21st century, pressure for species to shift north and to higher elevations will fundamentally rearrange North American ecosystems.
