World may be warming up even faster
Global warming could be faster and fiercer than expected, and new forests to soak up the greenhouse gas carbon dioxide may not help, according to research today from British scientists. Their computer models predict a rise in global average land temperatures of up to 6C in the next century, 2C higher than previous forecasts. The scientists foresee an Arctic in which sea ice in September is reduced dramatically to a couple of large floes in the middle of clear ocean. They forecast in Nature that bacteria will release carbon dioxide from warmer northern soils faster than forests can take it up. The rainforests of the Amazon will turn into arid savannah, releasing even more carbon dioxide. The 10 warmest years since records began have been in the past two decades. This year is expected to emerge as the fifth warmest ever. But during these two decades global average temperatures have risen by less than 1C. The new studies from the Met Office's Hadley centre for climate prediction point to temperatures never experienced in human history, and only matched in the era of the dinosaurs. "We have had warmer periods in the past," said Geoff Jenkins of the Hadley centre. "But the rate of warming is quite unprecedented." Nations of the world will meet in the Hague later this month to discuss ways of cutting carbon dioxide emissions to 5.2% below 1990 levels by 2012. Climate scientists point out that cuts of 60% are needed - and even if these were achieved now, the world would still warm by at least 1C, and sea levels would go on rising for a century. Nations have been talking of "carbon sinks" - new forests planted to absorb the extra carbon dioxide and cool the world. But the latest papers in Nature suggest that forests planted in Canada and Siberia would increase warming, making things worse. "The storms and floods being experienced across the UK are a wakeup call to the serious environmental threat posed by climate change," said the environment minister, Michael Meacher. "Public opinion has underestimated just how drastic and severe these phenomena are, and it has brought it home to people better than a million political speeches. We have got to build on that understanding and get agreement to much tougher action." Uncertainties about global warming rest on doubts about feedback. Snow and ice reflect sunlight back into space - and when these melt, dark ocean and forest absorb more sunlight and step up the rate of warming. On the other hand, more heat could mean more water vapour which could mean more clouds, reflecting more sunlight into space, thus cancelling some of the warming. With more carbon dioxide in the air, forests would grow more lustily, taking it up again and storing the carbon as wood and reducing the world's warmth. But water vapour is also a powerful greenhouse gas - and the effect of more vapour could cancel the cooling effect of the clouds. The latest research in Nature shows that forests would continue to mop up carbon dioxide until 2050 - but by then, soil bacteria would be releasing ever increasing amounts of carbon dioxide, and global warming would accelerate. All these scenarios assume a "business as usual" world in which nations go on burning fossil fuel at an increasing rate. "There are something of the order of seven gigatonnes - 7bn tonnes - of greenhouse gases being emitted. On current trends, by 2100, within the lifetime of our grandchildren, it could be 35-40 gigatonnes," said Mr Meacher. "The implications of that are mindblowing." A Foreign Office unit designed to prevent conflict over environmental issues was launched last night in London. The environmental policy department will help negotiations on climate change, forests, trade in endangered species, and biodiversity.