Weatherathome papers published in Bulletin of the American Meteorological Society

To what extent can extreme events be blamed on climate change due to rising greenhouse gas levels? The first set of studies to assess the extreme events of 2011 is published in the Bulletin of the American Meteorological Society (BAMS), examining how human and natural influences on climate contributed to the weather events of 2011.

Two papers from the weatherathome project are included in the Bulletin. Led by the University of Oregon, the first showed how the risk of the 2011 Texas heatwave and drought has increased substantially since the 1960s. The second, led by Neil Massey of the Smith School of Enterprise and the Environment at the University of Oxford, showed how the odds of an exceptionally warm November, such as 2011’s, have increased over the same period in the UK, while the odds of a cold December, like 2010’s, have fallen.

‘Where and when extreme weather events occur is still largely a matter of luck,’ explains Professor Myles Allen of the School of Geography and the Environment, University of Oxford, a co-author on three of these new studies, ‘but science can help us understand how different factors are loading the weather dice.’

Both these studies note that various factors have contributed to climate change since the 1960s but that most of the recent large-scale warming was very likely due to the observed increase in greenhouse gas concentrations. The third study, led by the Royal Netherlands Meteorological Institute, concluded human influence on global climate had little to do with the 2011 floods that devastated Thailand.

‘Not all damaging weather events that occur have been made more likely by human-induced climate change,’ explains Allen. ‘Some, like those cold winters, appear to have been made less likely, but can still occur by chance. Others, like those Thai floods, haven’t been affected either way as far as we can tell. Sorting these things out is essential in working out the true cost of climate change.’