Two superstorms Harvey and Irma hit North America recently. Many climate scientists are convinced these storms were boosted by global warming. Is there a smoking gun?
Where’s the evidence?
In climate science, that gold-standard evidence comes from observation over a long period of time. “It is incredibly frustrating,” said Dann Mitchell, an expert on atmospheric circulation at the University of Bristol in England. “We still can’t say with 100 per cent certainty that Hurricane Irma was enhanced by climate change, while with other extreme events—such as heat waves—we can”
A lot of scientists, however, think the case is already solid enough to nail down a conviction
But convincing as they may be, these remain “it stands to reason” arguments, not direct measurements of the major tropical storms known variously around the world as hurricanes, cyclones and typhoons, according to AFP. But some scientists say that clear trend lines have emerged despite these limitations
A study that sent shockwaves
Perhaps the strongest case that global warming has already exerted an influence on superstorms comes from Jim Kossin, a scientist at the US National Oceanic and Atmospheric Administration’s National Centers for Environmental Research
In a 2014 study that went largely unnoticed but sent shockwaves among hurricane experts, Kossin presented iron-clad evidence that cyclones around the world have been drifting poleward for thirty years, at the rate of 50-60 km per decade. This, he showed, could only be caused by global warming