World ‘warmest for 12,000 years
26/9/2006 BBC Earth has warmed by 0.6C (1F) over the past 30 years, research shows. The world is the warmest it has been in the last 12,000 years as a result of rapid warming over the past 30 years, a study has suggested. Nasa climatologists said the Earth had warmed by about 0.2C (0.4F) in each of the last three decades. Pollution from human activity was pushing the world towards dangerous levels of climate change, they warned. As a result, plant and animal species were struggling to migrate fast enough to cooler regions, they said. “The evidence implies that we are getting close to dangerous levels of human-made pollution,” warned James Hansen, head of Nasa’s Goddard Institute for Space Studies, New York. The study by researchers from Nasa, Columbia University and the University of California at Santa Barbara (UCSB), showed that warming was greatest at high latitudes of the Northern Hemisphere, and was more pronounced over land than the oceans. The reason behind the rise in temperatures in this region was a result of a loss in snow and ice cover, the researchers said. As the Earth warmed, melting snow and ice exposed dark land surfaces which absorbed more energy from the Sun, resulting in more warming - a process known as “positive feedback”. Warming was less over the ocean than over the land because of the great heat capacity of the deep-mixing ocean, which causes warming to occur more slowly there. Simon Tett, a scientist at the UK’s Hadley Centre for Climate Prediction and Research, said the findings supported Dr Hansen’s earlier predictions, which had been criticised in some quarters. “The results of this study show that James Hansen’s predictions of the late ’80s are consistent with what has happened,” Dr Tett said. ”Modelling has moved on since then, but the idea that early predictions were done to cause panic and were wrong has been proved to be not the case.” The study also showed that the recent warming had brought temperatures within about 1C (2F) of the estimated maximum of the past one million years.