It used to be the big debate in climate change circles. Whenever an extreme event occurred — like, say, Hurricane Katrina, or the deadly 2003 European heat wave — the question would immediately arise as to whether it was legitimate to in any way “link” it to climate change. Usually, some errant activist would draw the connection, and climate skeptics would pounce, denouncing the leap and questioning any causal attribution.
Over time, though, scientists have clarified matters. They’ve explained that while global warming doesn’t “cause” any single event, it can make them more likely to occur, not unlike (in the helpful analogy) the loading of dice. Indeed, published papers have shown that a warming climate had indeed increased the odds of a number of individual extreme events, including the 2003 European heat wave, the 2010 Russian heat wave and the 2013 Australian summer heat.
As we move further and further into a jarred climate, meanwhile, the research on attributing extreme events has also advanced. Thus, in a new study in Nature Climate Change, Erich Fischer and Reto Knutti, of the science-focused Swiss university ETH Zurich, perform an analysis not for any individual event but rather for all daily heat and precipitation extremes of a “moderate” magnitude occurring over land in our current climate. And they find, strikingly, that 18 percent of today’s moderate precipitation extremes, and 75 percent of moderate heat extremes, were made more likely to occur by global warming.
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