Climate change already influencing extreme weather events

Climate change is already affecting the frequency and intensity of extreme weather events, such as heat waves and heavy rainstorms, according to a new study.

The study, from the Swiss Federal Institute of Technology, has been published in the journal Nature Climate Change. The research calculates more than half of heat extremes and a fifth of heavy rainfall or snowfall has been influenced by manmade climate change and warns that as global average temperatures increase this could rise further.

The researchers note that these events are not solely connected to climate change, but warming increases their frequency.

Dr Erich Fisher, the study’s lead author, explains, “Extremes are rare by definition, a localised change in their frequency is statistically difficult to prove. But when all the measuring stations around the world are pooled, a clear picture emerges: there has been a global trend towards more frequent and intense hot extremes since the 1950s. In addition, significantly more stations have recorded increases than decreases in heavy precipitation.”

Following Europe’s summer long heat wave in 2003 scientists concluded that global warming has more than doubled the likelihood of such an event occurring.

The study also looks at how future temperature rises could impact extreme weather events. The international community has agreed to limit global warming to 2C above pre-industrial levels. However, the latest research suggests that this may not be ambitious enough.

The study finds that “with each increment of warming, the frequency of hot extremes and heavy perception events worldwide rises sharply”. For example, if temperatures rise globally by 2C the researchers would expect twice as many extreme heat events than would be seen with a 1.5C increase.

“These global warming targets, which are discussed in climate negotiations and which differ little at first glance, therefore have a great influence on the frequency of extremes.” Fisher said.

Photo: Gerwin Sturm via Flickr

Further reading:

Report: climate change to impact severity and frequency of extreme weather

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