Climate vs. Weather

An exellent blog post from the New York Times.  Brief and to the point.

Pitfalls of a Blue Sky Perspective

April 22, 2010, 4:39 pm

<!– — Updated: 4:41 pm –>Pitfalls of a Blue-Skies Perspective

By ELISABETH ROSENTHAL

A lone plane flying low over central London on Tuesday. From the ground, there was no indication of the cloud of volcanic ash billowing  through the atmosphere.Getty Images A lone plane flying low over central London on Tuesday. From the ground, there was no indication that a cloud of volcanic ash was billowing through the atmosphere at higher altitudes.
Green Science

Living under a cloud of volcanic ash in Europe has driven home for me the disconnect between the chemical reactions that take place high in the atmosphere – the ones that create “climate” – and the immediate weather conditions that we experience on the ground.

For much of the past week, a dense layer of dark volcanic ash made of sharp particles and toxic chemicals streamed through the atmosphere at altitudes from 15,000 to 50,000 feet, making flying impossible. But, I swear, each day here in England and then France, where I traveled next, was more glorious than the last. In two countries known for terrible weather, I enjoyed bright sun, crystal clear skies, light breezes. An early spring sunburn was my unforeseen souvenir from a walk south of London on Saturday.

The point is that changes in atmospheric chemistry are often not perceivable on the ground on a day-to-day basis — whether it’s the floating ash or an accumulation of the greenhouse gases that scientists say are causing global warming.

While long-term temperature trends are of course telling and important, the weather on your street is not much of an indicator of whether or not climate change is happening. And that creates a political challenge.

This winter, as London and Beijing and Washington were buried in snow, many people – among them political pundits – concluded that global warming was a scam. How can climate change be a problem if there’s two feet of snow in Philadelphia in March, or earlier-than-ever skiing in the Italian Dolomites in November?

At a climate forum I attended last week in London, David Adam, an environment reporter for The Guardian newspaper, wisely noted that this past winter was in fact very, very cold in some of the cities where the most powerful global opinion-makers and policymakers live, helping to tilt the public’s view toward deeper skepticism.

Yet winter cold or no winter cold, the National Oceanic and Atmospheric Administration just announced that this was the warmest March ever and the fourth-warmest January-to-March period. The combined global land and ocean average surface temperature last month was 1.39 degrees Fahrenheit above the 20th-century average of 54.9, the agency said.

Weather is no stand-in for climate.

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