The Sunday Times January 28, 2007 Last warning: 10 years to save world Jonathan Leake Environment Editor Scientists say rising greenhouses gases will make climate change unstoppable in a decade THE world has just 10 years to reverse surging greenhouse gas emissions or risk runaway climate change that could make many parts of the planet uninhabitable. The stark warning comes from scientists who are working on the final draft of a new report by the Intergovernmental Panel on Climate Change (IPCC). The report, due to be published this week, will draw together the work of thousands of scientists from around the world who have been studying changes in the world's climate and predicting how they might accelerate. They conclude that unless mankind rapidly stabilises greenhouse gas emissions and starts reducing them, it will have little chance of keeping global warming within manageable limits. The results could include the destruction of the Amazon rainforest and the Great Barrier Reef, the forced migration of hundreds of millions of people from equatorial regions, and the loss of vast tracts of land under rising seas as the ice caps melt. In Europe the summers could become unbearably hot, especially in southern countries such as Greece, Spain and Italy, while Britain and northern Europe would face summer droughts and wet, stormy winters. "The next 10 years are crucial," said Richard Betts, leader of a research team at the Met Office's Hadley Centre for climate prediction. "In that decade we have to achieve serious reductions in carbon emissions. After that time the task becomes very much harder." Among the scientists' biggest fears is that rising temperatures and levels of greenhouse gases could soon overwhelm the natural systems that normally keep their levels in check. About half the 24 billion tons of carbon dioxide generated by human activities each year are absorbed by forests and oceans -- a process without which the world might already be several degrees warmer. But as CO2 levels rise and soils dry, microbes can start breaking down accumulated organic matter, so forests become net producers of greenhouse gases. The sea's power to absorb CO2 also falls sharply as it warms. The latest research suggests the threshold for such disastrous changes will come when CO2 levels reach 550 parts per million (ppm), roughly double their natural levels. This is predicted to happen around 2040-50. "At the moment the real impact of our emissions is buffered because CO2 is absorbed by natural systems. However, if we reach this threshold they could be magnified instead," said Betts. "It means we must start the action needed to reduce greenhouse gas emissions in the next few years." His warnings were backed up by Dr Malte Meinshausen, a researcher at the Potsdam Institute for Climate Impact Research in Germany. He has used computer modelling to work out what might happen if greenhouse gas emissions were cut immediately, in 10 years' time or later. His results showed that immediate action might allow mankind to hold CO2 levels at 450ppm -- well below the 550ppm danger level. However, Meinshausen and his colleagues recognise that this is unrealistic because the world's governments are in such disarray over global warming. The best hope, they say, is that a global plan will emerge in the next few years, most likely from the renegotiations of the Kyoto treaty on reducing emissions. "We have to make sure carbon emissions peak no later than 2015 and then fall at around 3% a year. If we let them keep rising after that date it becomes much harder to bring them under control," said Meinshausen. His views were echoed by Dr Carol Turley of Plymouth Marine Laboratories who has been studying how rising CO2 levels are acidifying the ocean. When the gas dissolves in water it creates carbonic acid. "Rising acidity makes it much harder for marine organisms to build shells," she said. Turley, like the other scientists, has contributed to the IPCC report but all commented this weekend on the basis of already-published research. "If we do not take action in the next decade, by 2100 swathes of the ocean could have been stripped of creatures from plankton to coral reefs," she said. "Such changes would devastate ecosystems and fisheries."