Apocalypse soon if warming continues
The main findings of the UN climate panel about the risks of global warming:tech reviews Updated: Nov 18, 2007 01:20 IST
The main findings of the UN climate panel about the risks of global warming:
"Warming of the climate system is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level."
Causes of change
"Most of the increase in globally averaged temperatures since the mid-20th century is likely due to the increase in ... greenhouse gas concentrations" from human activities.
Global total annual greenhouse gas emissions from human activities have risen by 70 per cent since 1970. Concentrations of carbon dioxide, the main greenhouse gas, far exceed the natural range over the last 650,000 years.
Projected climate changes
Temperatures are likely to rise by between 1.1 and 6.4 Celsius and sea levels by between 18 cms and 59 cms this century.
Africa, the Arctic, small islands and Asian mega-deltas are likely to be especially affected by climate change. Sea level rise "would continue for centuries" because of the momentum of warming even if greenhouse gas levels are stabilised.
About 20-30 per cent of species will be at increasing risk of extinction if future temperature rises exceed 1.5 to 2.5 Celsius.
Reasons for concern
Risks to unique and threatened systems, such as polar or high mountain ecosystems, coral reefs and small islands.
Risks of extreme weather events, such as floods, droughts and heatwaves.
Distribution of impacts — the poor and the elderly are likely to be hit hardest, and countries near the equator, mostly the poor in Africa and Asia, generally face greater risks such as of desertification or floods.
Overall impacts — there is evidence since 2001 that any benefits of warming would be at lower temperatures than previously forecast and that damages from larger temperature rises would be bigger.
Risks such as rising sea levels over centuries; contributions to sea level rise from Antarctica and Greenland could be larger than projected by ice sheet models.