The other scare story of the century (weekly edition) is that the United States is in the grip of a massive drought caused by global warming. Everybody who’s everybody pounced including the Weather Channel. It’s hard to keep up; it seems only yesterday the US National Assessment was alarmed that the US was suffering from a century-long increase in extreme precipitation, although as we noted they had to do some creative cherry-picking of the start and end dates to get that result. And as we also noted, when compared to millennia-long records, 20th-century precipitation looks normal. But that’s not the end of it. Anthony Watts was on this megadrought claim like a downpour on a Nevada hillside, showing via maps from 1934 and 2019 that 2019 wasn’t even a drought year let alone a world-historic man-made one.
According to the Associated Press, the science is settled and we’re in a heap of trouble. “A two-decade-long dry spell that has parched much of the western United States is turning into one of the deepest megadroughts in the region in more than 1,200 years, a new study found. And about half of this historic drought can be blamed on man-made global warming, according to a study in Thursday’s journal Science.”
How bad is it? Well it’s big and it’s terrible. Tree rings from Oregon and Wyoming down to California and New Mexico show that this drought, the one that saw a wet 2019, is almost as bad as the one in 1575.
Some placid souls might remain calm in the face of news that continental North America is prone to droughts and experienced a worse one in the 16th century. After all, nobody thinks man was causing climate change back then. Though many deny there was such a thing as climate change back then, oddly without getting tagged as “deniers” just for saying there was nothing to see until the Industrial Revolution.
Hence this Associated Press story claims that it’s way hotter now than in the “dirty thirties” when you might think there was a real drought. Indeed it’s hotter than it ever was ever at all. Or not. In the real past, temperatures have been cycling up and down throughout the Holocene, the Pleistocene and the entire history of the Earth, and have normally been as much as 8˚ C higher than now. But never mind. According to New Scientist the new research showed that “potentially almost half of the current episode’s severity was down to human-caused global warming.” Potentially almost. Try taking that the bank. (And note that they drop their guard and say global warming not climate change. But we digress.)
As Eric Worrall points out in sneering at this study, the piece is quite open that droughts are cyclical and of course past ones in what’s now the American west weren’t due to human influence. Instead “the area was known to have suffered past extreme droughts due to natural cycles such as the La Niña climate phenomenon”. But that was “the past” when nature was variable. Now if anything happens we did it, in the atmosphere with the CO2.
Yes. Us. Associated Press quotes lead author A. Park Williams of Columbia University that “Even without climate change, we still would have had a drought. But this drought would have been no big deal without climate change.”
That last part is certainly true, since it’s been no big deal even with climate change. As for the rest, we’re having trouble swallowing it. Perhaps our throats are suffering a climate-related drought.
Or perhaps we’re choking on the following computer-generated pseudo-precision. Evidently the researchers used 31 entire computer models to compare the current state of the planet with what would be happening “without the burning of fossil fuels that spews billions of tons of heat-trapping gases.” Not to put the matter prejudicially through loaded terms like spew, you understand. But why should we trust their model-generated picture of what the world would be like without greenhouse gases since we already know the models can’t get it right with greenhouse gases? Especially since the models are getting worse over time, not better.
Such quibbles are evidently only for amateurs. Instead the experts stroke their long grey computer codes and inform us, as AP summarized it, that “They found on average that 47% of the drought could be blamed on human-caused climate change.” That’s the kind of precision you get from nearly three dozen lousy computer models instead of one good one. Yup. Not 46. Not 48.3. And not a suspiciously vague 50% aka “about half”. No sirree. Forty-seven percent on the nose.
Meanwhile as Watts notes, other studies have found that the 1934 drought was considerably more severe than the 1580 one and covered nearly three-quarters of western North America. Watts then prints another chart based on western US tree rings that shows a cycle of megadroughts and wetter periods that saw two monsters in the Middle Ages but has definitely been trending blue not red since 1500, with today’s a mere blip or, in his words, “miniscule by comparison”. That’s what nature does, with or without our help.