Brrr… this is global warming??

If you live in the Northeast or upper Midwest of the United States, it’s cold outside – very cold. I did a series of radio interviews on global warming yesterday, and I kept getting the same question: “How can there be global warming when it’s so cold outside??” Indeed, some talk radio hosts are now proclaiming that global warming is clearly a myth, given the current cold snap.

The science skeptics are at it again, so let’s go over the facts.

Global warming is about the long-term, decade-to-decade increase in the average temperature around the globe.

This cold snap is only in our corner of the world. While we are experiencing frigid temperatures, other folks are getting unseasonably warm temperatures:

• In Beijing, February temperatures are higher than at any time in recorded history. Trees are blooming and skating on the city’s normally solid lakes has been banned. More from AFP.
• In Sweden, the Alpine Skiing World Championships postponed the women’s Super G race because parts of the course were dangerously soft due to high temperatures. More from wire services.
• In southern Europe, a yearly dog sled race was cancelled last week because the Pyrenees Mountains have too little snow. More from Reuters.

Just as important, a short-term drop in temperatures does not add up to a climate trend. Just as the stock market can tick up and down during a general upward trend, local temperatures can move up and down during a general upward trend.

The long-term trend in temperatures is upward. The IPCC (see yesterday’s post) reported that global warming is “unequivocal” and “11 of the last 12 years (1995-2006) rank among the warmest years in the instrumental record.” A week of bitter cold in certain parts of the U.S. doesn’t change any of this.

Unfortunately, it’s not just skeptical radio hosts who make this mistake. For another look at flawed logic mistaking a short-term variation for a long-term trend, see the Wall Street Journal article I mentioned yesterday. It says: “The models didn’t predict the significant cooling the oceans have undergone since 2003 – which is the opposite of what you’d expect with global warming.” But look at these graphs of air temperatures from NASA (see original data) and ocean temperatures from the National Oceanic and Atmospheric Administration (see original article).

Every once in a while temperatures do dip for a few years. But those year-to-year variations are not related to a climate trend and cannot be predicted by a climate model. Climate models can be used to predict the longer-term trends in temperatures – which are clearly upward – and the models do this quite well.

The globe is heating up – scientists agree on that. In the meantime, if you’re in the Northeast or Midwest, pile on the sweaters to keep warm, but keep the thermostat low to help the planet.