The warning comes because of growing uncertainty about how fast emissions of greenhouse gases could grow, says the head of the IPCC team behind the recalculation, Nebojsa Nakicenovic of the International Institute for Applied Systems Analysis in Austria. Nakicenovic concluded that, with fast economic growth and low adoption of renewable energy, the real figure could be as high as 27 billion tonnes. Methane bubbling up out of reservoirs probably accounts for a fifth of all the world's emissions of the second most important greenhouse gas. This previously unsuspected finding comes from Vincent St Louis of the University of Alberta in Canada in a new analysis of studies of emissions from reservoirs round the world. It means that reservoirs could be responsible for 7 per cent of all global warming, and undermines the claims of hydroelectric dam makers that theirs is a greenhouse-friendly energy source.
Reservoirs cover an area of the planet six times the size of Britain.
Reservoirs in the tropics are probably the worst, but those that flood peat bogs in Canada could also be big emitters, says St Louis. Global warming is named the number one ecological threat to the planet in WWF's latest annual overview of the state of the planet, Living Planet Report 2000. Inhabitants of rich countries had a footprint four times larger than those of poor countries, said report editor Jonathan Loh. The biggest source of greenhouse-gases remains the US, where CO2 emissions rose 1.3 per cent in 1999. New scientific studies warn of increasingly weird and extreme weather to come.