Professor Myles Allen a climate scientist from the University of Oxford said while there is a suggestion cyclones may become more intense, the president�s assertion that climate change was causing more storms was not supported by science.

�It is a perfectly reasonable question for the president to be raising. Basic thermodynamics means that a warmer atmosphere, all other things being equal, makes more intense cyclones possible,� said Allen.

�But this does not mean cyclones have necessarily become more likely: indeed, the latest assessment of the UN Intergovernmental Panel on Climate Change stated explicitly that there is no clear evidence at present for any human-induced increase in tropic-wide cyclone frequency.

�On a personal level, I sympathise with the president�s evident frustration: he and the people of Vanuatu deserve an authoritative answer to the question of the role of past greenhouse gas emissions in cyclone Pam. The science isn�t there yet, but we are getting there.�

Weather@home 2013 Australia and New Zealand heatwaves and drought [hadam3p_anz] 72,172,281,000s
Weather@home 2014: the causes of the UK winter floods [hadam3p_eu] 61,225,243,00s
RAPID-CHAAOS [hadcm3n & hadcm3s] 74,039,203,00s + 12,220,935,00s

Other smaller experiments include:

HYDRA [hadam3pm2] 1,476,378,00s
Weather@home Climate Accountability: the causes of extreme heat in the Western US [hadam3p_pnw] 16,486,965,00s

See the full breakdown in this pie chart:


Thanks again to everyone for your support and contributions to the project!

Best wishes,
Hannah

In the summer of 2007 England and Wales experienced very heavy flooding. Summer precipitation and subsequently flooding are harder to model than winter or autumn rainfall and this recent publication highlights this again. We look at different possible drivers of high precipitation in summer and do not find a conclusive signal apart for the July precipitation which might have been exacerbated due to anthropogenic forcing. However, the focus of the paper is not so much the attribution of the extreme precipitation to external climate drivers but the quantification of the uncertainties involved in such a study. The paper is part of a special issue dedicated to exactly these issues which will soon be published in full.

"Another group, analyzing the heavy rains and floods that struck parts of Central Europe in June 2013, found no evidence that these could be attributed to global warming, even though such claims were made at the time.

Myles R. Allen, a researcher at Oxford whose group conducted the study on the European rains, noted in an interview that the science of attributing specific events to human emissions was still contentious and difficult, so any answers given today must be regarded as provisional.

His group has found a measure of human influence on several weather events over the years. But with the science still emerging, he cautioned against the tendency to cite global warming as a cause of almost any kind of severe weather.

'If we don�t have evidence, I don�t think we should hint darkly all the time that human influence must be to blame somehow,' Dr. Allen said."