Earth 30 September 2009
Video: Warmer world
The average global temperature is likely to be 4 °C higher than in pre-industrial times by 2055 if greenhouse gas emissions are not slowed – that means a 16 °C rise in the Arctic (Source: Met Office Hadley Centre)
By Shanta Barley, Nigel Hawtin, Catherine Brahic and Tom Simonite
Interactive feature: Explore the 4 °C world in Google Earth (.kmz file download
BY 2055, climate change is likely to have warmed the world by a dangerous 4 °C unless we stop pumping greenhouse gases into the atmosphere the way we do now. This is the startling conclusion of a study by the UK Met Office, unveiled at a conference in Oxford this week.
Why so soon? Because temperature rises caused by greenhouse gas emissions are expected to trigger dangerous feedback loops, which will release ever increasing amounts of greenhouse gases. The nature and scale of these feedback loops is a subject of vigorous debate among climate scientists, but warmer oceans, for instance, may liberate more dissolved CO2, and plants may decay faster in a warmer climate. The Met Office ran 17 different models with these feedbacks. All concluded a 4 °C world by 2055 was likely if emissions continue to rise. Even if we are lucky, we are still likely to hit 4 °C by 2070.