We Don’t Know if Global Warming Is Causing Droughts by Bjørn Lomborg.
“Everyone knows” that you should drink eight glasses of water a day. After all, this is the advice of a multitude of health writers, not to mention authorities like Britain’s National Health Service. Healthy living now means carrying water bottles with us, sipping at all times, trying to drink our daily quota to ensure that we stay hydrated and healthy.
Indeed, often we drink without being thirsty, but that is how it should be: As the beverage maker Gatorade reminds us, “your brain may know a lot, but it doesn’t know when your body is thirsty.” Sure, drinking this much does not feel comfortable, but Powerade offers this sage counsel: “You may be able to train your gut to tolerate more fluid if you build your fluid intake gradually.”
Now the British Medical Journal reports that these claims are “not only nonsense, but thoroughly debunked nonsense.” This has been common knowledge in the medical profession at least since 2002, when Heinz Valtin, a professor of physiology and neurobiology at Dartmouth Medical School, published the first critical review of the evidence for drinking lots of water. He concluded that “not only is there no scientific evidence that we need to drink that much, but the recommendation could be harmful, both in precipitating potentially dangerous hyponatremia and exposure to pollutants and also in making many people feel guilty for not drinking enough.”
The drink-more-water story is curiously similar to how “everyone knows” that global warming only makes climate more extreme. A hot, dry summer (in some places) has triggered another barrage of such claims. And, while many interests are at work, one of the players that benefits the most from this story are the media: the notion of “extreme” climate simply makes for more compelling news.
Consider Paul Krugman, writing breathlessly in the New York Times about the “rising incidence of extreme events” and how “large-scale damage from climate change is … happening now.” He claims that global warming caused the current drought in America’s Midwest, and that supposedly record-high corn prices could cause a global food crisis.
But the United Nations climate panel’s latest assessment tells us precisely the opposite: For “North America, there is medium confidence that there has been an overall slight tendency toward less dryness (wetting trend with more soil moisture and runoff).” Moreover, there is no way that Krugman could have identified this drought as being caused by global warming without a time machine: Climate models estimate that such detection will be possible by 2048, at the earliest.
More at Slate.