New Scientist Environment Blog, Catherine Brahic: …. A new study shows that human emissions of greenhouse gases made it 15 times more likely that the
So when data revealed that 2006, also an El Niño year, was the second-warmest year ever, Martin Hoerling at NOAA in Colorado and his colleagues decided it was time to find out if this was mere coincidence, or if El Niño was responsible for the warmth. Looking at data from 10 El Niño events since 1965, they found that El Niño tends to cool US temperatures slightly - not warm them.
The team have also used computer models to check this effect. They simulated
Finally, the El Niño and the greenhouse gas simulations were compared with what actually happened in 2006. The researchers found that the El Niño simulations were inconsistent with the idea that El Niño cause the 2006 temperatures. The greenhouse gas models, however, matched the actual records well. Hoerlin's team estimates that there is a 16% chance that 2007 will break the record set in 1998. The results will be published in Geophysical Research Letters on 5 September.
You might also be interested to know that this study is similar to one that was done in 2004 by Peter Stott of UK Hadley Centre for Climate Prediction and Research. Stott showed that human greenhouse-gas emissions at least doubled the likelihood that