Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes (Abstract, E. M. Fischer &R. Knutti, Nature Climate Change, Apr. 27, 2015)
Also discussed here: Human activity responsible for three out of four heat extremes, study finds (Roz Pidcock, The Carbon Brief, Apr. 27, 2015)
Today we review climate modeling research that examines the how the frequency of extreme weather events over the long term has and is being changed by the addition of greenhouse gases to the atmosphere. Results indicate that in addition to an average global warming of 0.85 C over the last 100 years that the probability of the temperature at a location exceeding a given threshold has tripled so that a daily maximum above 35C, say, that once occurred once in 3 years now occurs every year. When the global temperature has increased by 2C which is the present aim for international policy makers under existing climate change protocols, the probability of a hot day will increase 5 times compared to present day frequencies. Likewise the additional moisture that warmer air can carry has increased and this leads to heavier and more frequent rain storms and floods, especially in the tropics. While the link between climate warming and more frequent extreme events has been known in general terms for a long time, this is the first time that a quantitative number has been put on that- which has major impacts on insurance as well as on policy dealing with climate change.
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