Turning Up the Heat on Climate Change

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By time I was up and walking to work around 8 AM this morning in New York, the temperature was already 84 degrees and it’s forecast to hit a record-setting 102 degrees by 3 PM. The streets are a griddle, the offices are oppressive—more than usual—and I don’t even want to talk about the subways. Meteorologists are predicting that the entire East Coast will be trapped in suffocating heat for the rest of the week, thanks in part to a high-pressure area anchored off the Carolinas.

It’s summer in the city, as the Lovin’ Spoonful would advise, so what do you expect? But every major heat wave—especially the ones that occur in New York and Washington, where apparently the only things that ever matter happen—brings global warming back into the equation. Al Gore seems a lot more reasonable when you’re sweltering in a 99 degree DC office building.Will blazing days like this one become the norm if we fail to curb carbon emissions?

First of all, the usual caveat, which should be obvious but needs to be repeated: no single weather event can be said to be “caused” by climate change. Just as the record-breaking snowstorms of this past winter on East Coast didn’t disprove climate change, a record-breaking heat wave doesn’t seal the deal either. Weather and climate aren’t the same thing. To use a World Cup analogy (which allows me to link to more Lego football, this time in German), it’s as if the players on the soccer pitch represent the weather, and climate is the team manager. The day-by-day, week-by-week progress of weather is down to countless meteorological factors interacting—some in ways we can predict, others in ways we can’t. But climate sets the overall game plan—so some parts of the world will always be hotter or drier or wetter than others, just like the Germans will always be strong and efficient, the Dutch will be creative and the English will always be sad disappointments.

That means that as climate changes, it will change the parameters for weather as well. Figuring out exactly how a changing climate will change weather, however, is one of the trickiest parts of any climate models. The further out we try to predict weather, the tougher it is—but with climate, we have strong predictability over the very long term, meaning centuries or more, but less certainty for the near future. There’s a long-running scientific debate over the effect warmer temperatures will have on tropical storms, though a loose consensus has formed around the theory that climate change could result in stronger storms, if not necessarily more of them. But we can say with some assurance that a warmer world will be, well, warmer, with more frequent and more intense heat waves, as this graph from the Intergovernmental Panel on Climate Change and the Centers for Disease Control shows:

Shifts in the Distribution of Cold and Hot Weather

It’s already happening: last month the National Oceanic and Atmospheric Administration announced that the January through May period this year was globally the hottest on record, with the average temperature in May 0.99 degrees above the 20th century average. (Meaning that during those March snowstorms that had climate skeptics building igloos, on a global basis, climate change hadn’t taken a break.)

And heat waves are about more than just uncomfortable sweatiness and short-fuse tempers. The Earth Policy Institute, a Washington environmental think tank, estimates that nearly 35,000 people died during the major European heat wave of 2003, when morgues in countries like France and Germany—unused to dealing with the heat—overflowed with the bodies of the elderly, who are particularly vulnerable to high temperatures. Of course, as writers like the climate contrarian Bjorn Lomborg have pointed out, cold winters tend to be even more deadly that hot summers, and since climate change will mean warmer winters as well, the overall impact on mortality might be blunted. But sizzling heat could ruin agriculture as well: a study in Science last July found a more than 90% chance that by the end of the century, average growing-season temperatures would be hotter than the most extreme levels recorded in the past, as I wrote on last summer:

And the extreme heat will wilt our crops. [David] Battisti and [Rosamond] Naylor looked at the effect that major heat waves have had on agriculture in the past — like the ruthless heat in Western Europe during the summer of 2003 — and found that crop yields have suffered deeply. In Italy, maize yields fell 36% in 2003, compared with the previous year, and in France they fell 30%. Similar effects were seen during a major heat wave in 1972, which decimated farms in the former Soviet Union, helping push grain prices to worryingly high levels. If those trends hold in the future, the researchers estimate that half the world’s population could face a climate-induced food crisis by 2100.

Warmer winters won’t do us much good if we can’t feed ourselves while enjoying a balmy February. Something to think about during summer on Planet Earth.