Warming caused by human activities played a key role in 6 out of 12 extreme weather events that occurred last year, according to a new report.
Scientists have released a report in the Bulletin of the American Meteorological Society in which they study the causes of 12 weather events from 2012, such as droughts, loss of Arctic ice, hurricanes, heavy rainfalls and heat waves.
They found that natural changes in climate patterns have a big influence. However, they say that human activities and manmade climate change have also been a decisive factor in half of these phenomena.
Thomas Peterson, one of the lead editors on the report, said, “Scientists around the world assessed a wide variety of potential contributing factors to these major extreme events that, in many cases, had large impacts on society. Understanding the range of influences on extreme events helps us to better understand how and why extremes are changing.”
For instance, the report found that the magnitude of warmth of the 2012 US spring heat waves was largely influenced by human-driven climate change, which also increased the likelihood of such events by four times.
The loss of Arctic ice due to warmer seas and atmosphere “cannot be explained by natural variability alone”, the report says.
Extreme rainfall – like that which hit the UK – has also been affected partly by natural variability, but also from an increase of global temperatures linked to anthropological climate change.
Thomas R. Karl, director of National Oceanic and Atmoshperic Administration (NOAA) Climatic Data Centre, commented, “This report adds to a growing ability of climate science to untangle the complexities of understanding natural and human-induced factors contributing to specific extreme weather and climate events.
“Nonetheless, determining the causes of extreme events remains challenging”.