There Is a Big Difference Between Weather and Climate

My sister-in-law lives in Wisconsin, just across the St. Croix River from the Twin Cities. It’s been snowy and cold of late, and she didn’t need to hear from her kid sister the other day that the crocuses are blooming in Seattle.

It’s been unusually snowy and cold in lots of places recently. Global average temperatures have taken a dip.

Millions of Chinese had their New Year travel plans disrupted by blizzards.

It snowed in places that normally are associated with scorching weather, such as Johannesburg and Baghdad.

In Miami, heat-loving iguanas dropped out of the trees during a January cold snap.

“Proof,” the climate denial lobby is bellowing, that global warming is passe and that climate alarmists should find something else to hoodwink the people about.

Once again, we see a failure, accidental or deliberate, to distinguish between weather and climate, which leads to public confusion that serves the interests of those opposed to legislation reducing greenhouse gas emissions.

Weather is a short-term phenomenon. Climate is long-term. Short-term phenomena often have random fluctuations that mask a long-term trend, or even seem to throw it into reverse. Over a longer period of time, the fluctuations tend to smooth out and the long-term trend becomes clearer.

It can be dangerously misleading to announce a long-term trend on the basis of short-term data, as the climate change deniers are attempting to do.

Let’s illustrate the distinction with a prosaic scenario.

Say you’re watching the Yankees play the Red Sox at home and Alex Rodriguez is not on his game. He strikes out three times and pops up in a clutch situation with men on base. The boo birds are out in force.

Would the team general manager decide, on the basis of one game worth of data, that Rodriguez is washed up and should be traded to Pittsburgh? Not bloody likely. He knows the difference between short-term fluctuations and long-term trends – Rodriguez’s .306 lifetime batting average and his 518 career home runs, for example. And the GM knows that such a trade would enrage fans who also grasp the distinction, and they would likely run him out of the Bronx in a heartbeat.

Like A-Rod’s Hall of Fame batting average, the rise in global average temperatures is a long-term trend that has been documented with multiple lines of evidence.

But even when there is a powerful long-term trend, short-term fluctuations that mask the trend, or even seem to reverse it, won’t go away. Occasionally, Alex Rodriguez will have bad days when he can’t find the ball. In a warming world, there will still be winters in the temperate and polar regions, and from time to time, there will be cold waves.

Climate scientists say the recent cooling likely is one of those short-term fluctuations, aggravated by the La Nina pattern out in the Pacific.

So, this winter, it got cold enough in South Florida to make life miserable for the iguanas. That doesn’t mean, however, that global cooling has arrived, as the deniers would like us to think. Ask them if they think there’s a business opportunity selling parkas and mukluks in Miami.

As NASA climatologist Gavin Schmidt told the New York Times recently, “it’s all in the long-term trends.” Which reminds me. I should reassure my sister-in-law that the crocuses should be popping up anytime.

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