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Our Common Future Under Climate Change
International Scientific Conference 7-10 JULY 2015 Paris, France
Guildford England Dec 2015
Extreme weather events: Are humans to blame?
201507-09
By Fay Newbery, University of Reading
Human actions have substantially increased the odds of extreme warm years and summers according to research by the director of the Pacific Climate Consortium.�
�What would have been a 25 year [extreme] event has become a 15 year event,� says Francis Zwiers at Our Common Future Under Climate Change conference taking place in Paris from 7-10 July.
Future climate depends on the magnitude of a number of �forcing� factors such as the level of CO2 in the atmosphere. These levels change due to human actions such as deforestation and use of fossil fuels, but change also occurs due to natural processes such as volcanic activity.
By separating projected human and natural sources of forcing factors, it is possible to look at future climates that might exist in the presence of only natural systems or with the addition of human actions.
Scientists can examine weather patterns modeled for these future climates to show the probability of extreme events. If extreme events are more likely in climates resulting from human actions then that�s our answer: we do carry some of the blame.
The 2003 European heatwave that resulted in 35,000 deaths was the most extreme event of its kind since 1500 AD.�
�Human influence has very likely at least doubled the likelihood of such an event,� said Peter Stott from the Met Office Hadley Centre, UK.�
�Heat waves that would be expected to occur twice a century in early 2000s are now expected to occur twice a decade.�
In the UK, human influence has made breaking the current UK temperature record �about ten times more likely,� Stott continues.
Evidence is more mixed for rainfall extremes but anyone affected by the floods in Southern England during the winter of 2013/14 will be wondering whether the wettest winter on record will be repeated.
Fay Newberry is a PhD student at the University of Reading studying climate effects on crop disease. She is part of the volunteer social media team at the Our Common Future Under Climate Change conference.
This is part of a blog series profiling climate scientists, economists, social scientists and civil society members who are presenting and discussing innovative climate science at Our Common Future. For more follow @ClimatParis2015 and #CFCC15 on Twitter.