Climate change caused by global warming will have powerful but varied effects on the world's regions over the next century, according to a report unveiled here yesterday by a UN scientific group.
The document was compiled by a working group of the Intergovernmental Panel on Climate Change (IPCC), part of a massive effort to update knowledge on the scale and impact of global warming.
The panel calculates that the so-called "greenhouse effect" of carbon dioxide (CO2), caused by unhindered burning of fossil fuels, will cause the Earth's atmosphere to warm by up to 5.8 degrees by 2100.
Here is a summary of the expected consequences on the major regions, according to the document:
Asia
The developing countries of Asia are highly vulnerable to global warming. The developed countries of the continent are more able to adapt and less vulnerable; natural resources are already under stress.
The biggest problem is food insecurity. Drier soils, increased flooding, stronger winds from tropical cyclones and the possibility that pests may proliferate under climate change will affect Asia's crops.
Farmers in northerly latitudes will benefit from warmer temperatures.
Asia is likely to become more vulnerable to extreme weather events, such as typhoons, droughts and floods.
Sea-level rise and an increase in the intensity of tropical cyclones could displace tens of millions of people in low-lying coastal areas. The land of these areas could be turned infertile by salinisation.
Rainfall will intensify and increase flood risks in temperate and tropical Asia.
Human health will be threatened by an increase of vectorborne infectious diseases like malaria and increased heat. Climate change will increase energy demand and decrease tourism attraction.
Biodiversity, which is already threatened by population pressure and deforestation, would be even more at risk.
Africa
Poor, confronted with frequent droughts and floods, heavily dependent on rain-fed agriculture, Africa lacks the economic resources and technology to adapt to climate change and is particularly vulnerable to global warming, the experts say.
One of the biggest problems is water, as major river basins are highly sensitive to climate variation. Run-off and water availability will decrease in Mediterranean and southern countries of Africa.
Increases in droughts, floods and other "extreme events" will aggravate water scarcity.
Food security and development will be constrained by decrease in grain yields and additional water stress. Food security will be particularly at risk in small food-importing countries.
In southern, north and west Africa desertification will be "exacerbated" by reductions in average annual rainfall, run-off and soil moisture.
Sea-level rise will increase the risks of flooding, erosion and saline intrusion in coastal settlements, for example in Senegal, Gambia, along the Gulf of Guinea and in Egypt.
Temperature increases will encourage the outbreak of viruses, bacteria and mosquitoborne parasites in areas of poor sanitation, while warmer coastal waters could aggravate cholera epidemics in coastal areas.
"Significant extinctions" of plant and animal species are projected. They could impact on livelihoods in rural settlements and tourism.
Europe
The predicted effects of climate change will be substantial in some areas, but as a whole, Europe has the financial resources and knowledge to adapt.
The biggest risk is river flooding, which will increase across much of the region.
The worst-hit areas will be in southern Europe, which will become hotter, drier and vulnerable to water shortages. In northern Europe, warmer temperatures could mean a boost for farmers.
Half of the Alpine glaciers and large permafrost areas could disappear by the end of the 21st century. Habitat change will be significant and some animal species could disappear.
The economic impact is likely to be felt in the Mediterranean, which will be less attractive as a summer holiday destination, and in ski resorts, which could find themselves without snow. Insurance companies will face bigger bills from flood damage. The biggest impact on health will mainly be heat-related.
North America
Climate change will have widely varied effects in the United States and Canada. Some states and cities will be harder hit than others, suffering heat stress, water scarcity and higher risk of flooding.
Sea-level rise is expected to enhance coastal flooding and erosion and the risk of storm surges, particularly in Florida and much of the Atlantic coast.
Water will become a contentious issue. "Some regions may see reduced water use in irrigated agriculture and a movement of the use of available water supplies increasingly to urban and other relatively highly valued uses," the report says.
As for food production, the experts say they are highly confident that "modest warming" would benefit some crops. Production in the grain belt, in the US Great Plains and the Canadian prairies may be somewhat affected by increased drought, but there are also opportunities for growing crops farther north in Canada as the weather warms.