Global warming is the climate ogre
UNITED STATES: From recordbreaking heatwaves to catastrophic floods, extreme weather these days tends to quickly inspire the same question: is climate change the culprit?
The answer is never simple. It’s almost impossible to blame any individual climate or weather event entirely on global warming, when there are so many complex physical factors that may cause them to occur.
But scientists are getting better at figuring out to what extent climate change may have increased the probability or the severity of any given event.
Now, a group of scientists has extended this field of research to a global scale. In a new study, they have analysed the influence of global warming on extreme climate events all over the world. And they’ve found that climate change has had a substantial effect.
The study suggests that anthropogenic global warming, as it has advanced, has had a significant hand in the temperatures seen during the hottest month and on the hottest day on record throughout much of the world.
It finds that climate change substantially increased the likelihood of these record warm events occurring in the first place, and also made them more severe than they otherwise would have been, in more than 80 per cent of the observed world.
‘‘This suggests that the world isn’t yet at a place where every single record-setting hot event has a human fingerprint, but we are getting close to that point,’’ said Noah Diffenbaugh, a climate scientist at Stanford University and lead author of the new paper.
‘‘Greater than 80 per cent of those record hot events is a substantial fraction.’’
The study also finds that climate change has increased the probability and severity of the driest year on record in 57 per cent of the observed areas of the world.
It has also found that for the wettest five-day period in each of these areas, warming has increased the chance of it occurring in 41 per cent of the observed areas of the world.
Some of the strongest effects of climate change on these extremes were seen in the tropics. This was a stark reminder that ‘‘a lot of the burden for climate change falls on regions that have emitted only a tiny fraction of the CO2 that caused the shifts’’, said Gabriele Hegerl, a climate scientist at the University of Edinburgh and coleader of a World Climate Research Programme project focusing on weather and climate extremes.
Finally, the study suggests that global warming contributed substantially to a record low in Arctic sea ice extent in 2012 as well.
‘‘There’s been an explosion of research into possible connections between global warming and indi- vidual extreme climate events,’’ Diffenbaugh said.
Just at the end of last year, for instance, a special report in the Bulletin of the American Meteorological Society described a number of extreme events from 2015, including cyclones, heatwaves and wildfires, that were likely influenced by climate change.
To date, much of this type of research had been in the form of case studies on individual events, Diffenbaugh noted.
But in the new paper, he and his colleagues analysed a variety of different types of climate extremes all across the world using different approaches designed to investigate the influence of global warming.
– Washington Post