We’re Snowed Under! What Happened to Global Warming?
I just saw a piece on the National Review’s online site with the provocative title “Cold is Weather, Heat is the Wrath of the Climate Gods,” by Brendan O’Neill. The author was incensed by a piece he’d seen on an environment blog hosted by Britan’s Guardian newspaper suggesting that anyone who sees Europe’s bizarrely cold and snowy weather (America's been getting it, too) as evidence against global warming is an idiot. “…the avatars of climate change have been over-interpreting changeable weather for years,” writes O’Neill, so it’s pretty hypocritical of them to blast the skeptics for doing the same thing.
He’s got a point. There is a difference between climate—the long-term, average conditions in a given location—and weather, which is a series of temporary variations on that long term theme. Those variations can be dramatic—heat waves, cold snaps, droughts, severe storms—but they aren’t representative of the underlying climate (that’s why they’re called variations; go here for a fuller explanation)
One way to see the difference is to look at a particular weather event, like this month’s cold snap, in the context of the entire planet. Northern Europe and parts of the U.S. are indeed colder than normal. But big swaths of the planet aren’t. Here’s a map that shows how the temperature is varying worldwide, from Britain’s Met Office. co-author.
If a small part of the globe is colder than average and a big part is warmer, that suggests that global warming hasn’t stopped by any means. Record cold snaps will continue to happen, even as the world continues to heat up—and in fact a recent study in Geophysical Research Letters by several scientists, including Climate Central’s own Claudia Tebaldi, cites plenty of daily record low temperatures over the past decade in the continental US But it shows that daily record high temperatures occurred twice as often; in a world without global warming, you’d expect them to be roughly equal.
Sometimes even a global shift can be temporary. In 1998, global temperatures shot up significantly over the previous year. The reason, it turns out, was due to an especially strong El Nino, a massive warming current that shows up periodically in the Pacific. Did that mean global warming had suddenly accelerated? Not at all.
But people who want to sound the alarm on global warming sometimes imply that such events—or the record melting of Arctic sea ice in 2007, or even a hurricane like Katrina—as evidence that global warming has indeed gotten worse.
The truth is that it’s risky to consider one event, even a worldwide event, as proof of anything, even though we instinctively feel that it might be. It's the longer-term trends that give scientific confidence. The trends over the past century, and the trends most climate scientists see for the coming century, do indeed point to global warming as a real and present danger.
But that’s not an obvious point to most people—and it’s one that even people who know better sometimes forget. The best antidote to misinformation is information—and the word “idiot” is generally unnecessary.