Weather extreme temperatures, like the Russian heatwave from 2010 and the Texas drought in 2011, have been considered to be effects of climate change before – but the blame for individual events to it is still intensely debated.
Reto Knutti and Erich Fischer from the Institute for Atmospheric and Climate Science in Zurich, Switzerland, analyzed how human activity is impacting on the planet. Using two dozen climate models, they managed to calculate how the odds of extreme events have changed along with the rise in global temperatures.
Their results reveal that global warming of 0.85 °C which was registered since the industrial revolution has had a strong effect. Climate change is now to blame for 75 per cent of our extremely high temperatures and 18 per cent of heavy rainfall, according to the research. The most extreme particular events are more likely to be caused by global warming, the scientists claim.
“A 1-in-10,000 day heat event is something that’s only expected to happen every 30 years. But in a global-warming world, it’s turned into a 4-in-10,000 day event. Three of those hot days – or 75 per cent – would never have happened if global warming wasn’t around,” explained Fischer.
Even though global warming isn’t the only factor of extreme weather, it is one of the most important.
Fischer and Knutti also considered what would happen if the climate would experience a 2 °C increase, a level that many researchers warn would be hazardous to exceed. In this world, global warming would be accountable for more than four of every ten extreme rainstorms, they discovered.
In another research paper, which accompanied the study, Peter Stott from the Met Office Hadley Centre in Exeter, UK, claims that this results must be a “sobering thought” for policy-makers whom are aiming to protect their cities and countries from natural disasters.
The numbers confirm what climate researchers already suspected, according Francis Zwiers, a statistician at the University of Victoria in British Columbia, Canada. He added, that the new data can help us determine whether an extremely hot day is the result of chance or global warming.
“You can turn that question into an answer. We shouldn’t be quite so surprised when what was formerly a once-in-a-20-year event occurs. We should be expecting it,” Zwiers said.
Image Source: KESQ