Human activities made 2015 heat waves more intense

Scientists have found strong evidence that human-induced climate change increased the severity of heat waves that hit India, Pakistan, Europe, East Africa, East Asia and Australia in 2015, helping to make it the warmest year on record.

25 peer-reviewed research papers featuring the research of 116 scientists from 18 countries all point to one, unavoidable conclusion: human activity had a strong influence on extreme weather events over five continents and two oceans in 2015.

The strongest evidence for a human influence was found in the increased intensity of numerous heat waves in countries such as India, Pakistan, China, Indonesia, Japan and Australia, as well as across Europe. Record-low Arctic sea ice in March, Alaska’s intense wildfire season, extreme rainfall in southeast China in May and extreme drought in southwestern Canada were also likely influenced by climate change.

“As we get better at distinguishing the influence of climate change from natural variability, the local significance and impacts of this global phenomenon are becoming clearer,” said Stephanie C. Herring, a scientist with the National Oceanic and Atmospheric Administration (NOAA) and lead editor of a special report compiling the research papers.

A number of other weather events in 2015 were likely made more extreme by climate change, including the “sunny day” tidal flooding event that inundated coastal areas in Florida in September that year. According to one study, the probability of such an event occurring again has increased by 500 per cent since 1994. Human-induced climate change also likely contributed to record amount of winter sunshine in the United Kingdom.

“With this report, we continue to document scientists’ growing ability to identify how climate change influences today’s weather,” said Jeff Rosenfeld, editor-in-chief of the Bulletin of the American Meteorological Society. “These accessible and brief papers show the scientific community and the public that once seemingly impossible insights about climate impacts are now within the capability of timely, rigorous science.”

The authors chose the event they wished to study, which means that the research papers are neither a random sample nor a comprehensive survey of the extreme weather events of 2015, explained Herring.


Image credit: Ray Garrido, courtesy of Washington Department of Ecology

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