Open Mind

Who the heck started all this global warming fuss anyway?

November 15, 2006 · Leave a Comment

I think we can give the credit — or blame — to Svante Arrhenius. He was a Swedish chemist, a Nobel prize-winner, a pretty smart guy. In 1896 he concluded that changing the carbon dioxide level in our atmosphere could alter, and in fact had altered, the temperature of planet Earth [On the Influence of Carbonic Acid in the Air Upon the Temperature of the Ground, Philosophical Magazine 1896(41): 237-76]. He wasn’t the first to theorize that altering the amount of CO2 and other atmospheric gases could change global temperature, but he was the first to suggest that it had actually happened — it might even have caused the ice ages.

Arrhenius estimated that doubling CO2 would raise temperature an average of 5 degrees Celsius (9 deg.F). Today’s estimate: from 1.5 to 5 deg.C. It’s actually quite impressive that in spite of crude data and models, he was squarely in the ballpark. A few years later he wrote a popular book in which he suggested that release of CO2 from human activity would warm the future earth. Based on the emissions rate in his time he expected CO2 doubling to take about 3000 years (plenty of time to adapt), and thought it would be a good thing, as it would stave off the next ice age.

That was a century ago. Since that time, CO2 has risen much faster than Arrhenius expected, increasing about 30% in the last 100 years. At the same time, global temperature has risen by about 0.8 deg.C. Arrhenius’ prediction — increased CO2 and increased temperature — has come to pass.

And that is quite persuasive evidence: predict something before it happens, then see it happen. There’s no such thing as an infallible test, but this is as close as it gets. The “experiment” has actually happened — quite beyond our control. Fortunately we recorded the results.

We’ve also learned a lot more about climate and weather. We still can’t predict whether it’ll rain ten days from now, but we do know that CO2 really does trap heat at earth’s surface, warming the planet as a whole according to the expected pattern. Both theory and observation have provided confirmation after confirmation that global warming is more than a theory; it’s a reality. Climate scientists now speak with a near-unanimous voice that it’s not just really happening, it’s a threat to our well-being. Not just a few climate scientists, or just “most” climate scientists; an overwhelming majority are trying to warn us of the dangerous consequences of our actions. Why are they so convinced? Because the experiment has already taken place, and we saw what happened.

No-brainer, right? Unfortunately, the obvious solution — don’t put more CO2 into the atmosphere — means doing something about oil, gas, and coal, the main sources of carbon for that CO2. And that means tampering with some very big money. Hence Global Warming is now a “hot” political issue. At the urging (and funding) of the fossil fuel industry, there’s a sizeable effort to cloud the issue. There are hundreds of web sites giving out mis-information, some of it brilliantly crafted. There are TV ads (“CO2: they call it pollution, we call it life”). There’s even a senator from Oklahoma who calls global warming the “greatest hoax ever perpetrated.”

But if the experiment actually happened (it did), and we’ve seen the results (we have), then how can they make a case? Mostly it boils down to this: we can’t repeat the experiment. Not for another 20-30 years at least, anyway. This enables denialists to claim that the sun is getting hotter, or it was warmer in medieval times, or that galactic cosmic rays control the climate, or a host of other theories that can’t really be tested for another 20-30 years or so, are sometimes just plain ridiculous, and rarely agree with each other. Arrhenius made his prediction 100 years ago, we saw it happen, and the vast majority of experts agree the evidence points to exactly the reason he suggested: man-made greenhouse gases.

Categories: Global Warming

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