Extreme weather already on increase due to climate change, study finds

http://www.theguardian.com/environment/2015/apr/27/extreme-weather-already-on-increase-due-to-climate-change-study-finds

Karl Mathiesen
April 27, 2015

Extreme heatwaves and heavy rain storms are already happening with increasing regularity worldwide because of manmade climate change, according to new research.

Global warming over the last century means heat extremes that previously only occurred once every 1,000 days are happening four to five times more often, the study published in Nature Climate Change said.

It found that one in five extreme rain events experienced globally are a result of the 0.85C global rise in temperatre since the Industrial Revolution, as power plants, factories and cars continue to pump out greenhouse gas emissions.

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What represents an extreme day varies depending on the background climate. In the south-east of England, for example, temperatures used to reach 33.2C once every 1,000 days, but are now happening as much as once every 200 days.

Future warming will bring a more volatile, dangerous world, even if the world manages to keep temperature rises within a 2C limit to which governments have committed, Fischer’s research found. On average, any given place on Earth will experience 60% more extreme rain events and 27 extremely hot days.

Numbers of extreme weather events spiral even higher at a rise of 3C, a level of warming that the world is on track to exceed with current levels of manmade global greenhouse gas emissions.

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The study shows warming of the atmosphere increases the number of times temperatures reach extreme levels and evaporates more water from the oceans. It is from this hotter, wetter background that extreme weather events emerge.

Longer events, such as heat waves and prolonged rainy periods, will also occur more often.

“When we talk about 15-day precipitation or 15-day heat waves rather than one-day cases, one very robust finding is the longer the period the higher the fraction that is attributable to warming,” said Fischer.

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tags: extreme weather