Winter Returns

Winter returned with gusto today. I am very happy.

It is January. And this is New England. It's supposed to be winter, and it's supposed to be cold.

But you'd never have known it around here last week, when the thermometer broke into the 50s and took a siesta. Pasty arms and legs revealed themselves about five months early. I even saw landscaping trucks making the rounds.

Then the storm came overnight and dumped heavy, wet snow on us. Temperatures fell back to freezing, and order had been restored.

We'll see how long it lasts.

Have you all noticed the extreme vacillations? It's happening nationwide. Hurricane force winds from a storm in the Pacific Northwest that plops 10 feet of snow on the Sierra Nevadas in a single day. Tornadoes in January in parts of the Midwest. The weather is like a yo-yo across America, except maybe in the Southwest, where it's got two settings: hot and hotter.

Yes, yes, weather is always extreme. Climate is random. The dynamics shaping the oceans and atmosphere (by far the two main components of climate) are complex. And you can't look at a snapshot of the weather and draw some broad, general conclusion.

Yes, but there is little doubt in my mind that what we are seeing are manifestations of global warming. Maybe small, early signals, but signals nonetheless.

A story last month said 2007 was on pace to be the seventh hottest year since record keeping began in 1850. If that holds, 11 of the hottest years on record will have occurred in the past 13 years. That, my friends, is a sign.

The Arctic ice cap set a new low this summer since NASA satellite mapping began in 1979. That, my friends, is another sign.

The Greenland ice sheet is melting faster than before. That, my friends, is yet another sign. (The cause is less certain, however.)

And I hope we all know that carbon dioxide levels in the atmosphere (the main contributor to global warming) continue to rise. That, my friends, is a very bad sign. We know this because hundreds of thousands of years of climatic data tell us that when carbon dioxide levels in the atmosphere go up, temperature rises are sure to follow.

It's like we're driving down a road with sign after sign telling us the bridge ahead is out, with each sign bigger than the last. But we, the driver, cannot see that far, so we're reluctant to believe we have a plunge ahead.

Our climate, in my mind, is telling us the same thing.

Will we take note?