Global floods and extreme rainfall events have surged by more than 50% this decade, and are now occurring at a rate four times higher than in 1980, according to a new report.
Other extreme climatological events such as storms, droughts and heatwaves have increased by more than a third this decade and are being recorded twice as frequently as in 1980, the paper by the European Academies’ Science Advisory Council (Easac) says.
The paper, based partly on figures compiled by the German insurance company Munich Re, also shows that climate‐related loss and damage events have risen by 92% since 2010.
Prof Michael Norton, Easac’s environmental programme director, said that greenhouse gas emissions were “fundamentally responsible for driving these changes”.
“Trends towards extremes are continuing,” he said. “People have experienced extreme weather already — big switches [between] warm and cold winters — but the frequency of these shifts may be changing.”
“Some of the underlying drivers of extreme weather which were speculative four years ago are now looking less speculative and [more like] credible hypotheses. That is the weakening of the Gulf Stream and the meandering behaviour of the jet stream.”
The Easac study, Extreme weather events in Europe: Preparing for climate change adaptation, looked at new data and models focused on a potential slowdown of the Atlantic Gulf Stream, due to an influx of freshwater from melted ice sheets in Greenland.
It was compiled by experts from 27 national science academies in the EU, Norway and Switzerland, although the paper was not peer‐reviewed.
The UN’s Intergovernmental Panel on Climate Change (IPCC) has assessed the probability of a slowdown before 2100 at more than 90% — or “very likely”. However, a complete “switch off of the gulf stream – or Atlantic Meridional Overturning Circulation (AMOC) – is increasingly thought possible by some scientists.
Some studies say this could lower land temperatures in the UK, Greenland, Iceland and Scandinavia by up to 9C.
UK arrays positioned in the north Atlantic measured a 30% drop in AMOC strength between 2009‐10, the Easac study says. And while uncertainties persist about the pace and scale of possible future changes, the decline in Gulf Stream strength itself has now been “confirmed”.
Citing “gathering evidence of an emerging negative phase” in Atlantic temperature swings driven by a weakening Gulf Stream, the study calls for research to be stepped up.
“With potentially substantial implications for the climate of north‐west Europe, it is clearly desirable to quantify this risk further,” it says.
First published in The Guardian, 21 March 2018