January 4, 2010
It was obvious to me that something was up in 1993 or earlier, because I remember thinking (when we bought our house) “this is high enough to be dry even if Greenland melts”.
It’s supposed to be obvious, that CO2 and CH4 are greenhouse gasses (GHGs), meaning that they are transparent to visible radiation, but absorb and re-radiate (both up and down) heat radiation.
What convinced me that change was underway, back in the early 1990s, was the data in the Keeling CO2 record. Not only is the CO2 increasing, but the growing cycle is getting longer, and CO2 levels are peaking earlier — meaning, most likely, a longer growing season.
Back then, simulations were still somewhat vague, and there was still concern over the quality of the temperature data from ground stations — perhaps human activity near the ground stations was the cause, not global warming. But the Keeling data is collected at the top of a mountain in the middle of the Pacific, with plenty of room for mixing, and little change in nearby (elevation-wise) data.
Historical data is also pretty convincing.
And, of course, now the Northwest Passage is becoming navigable.
Just recently, I stumbled across this nice summary of observed correlations in GHG changes and measured changes in heat radiation. That is, they looked for heat radiation changes of exactly the sort predicted by an increase in greenhouse gasses, and found them.
It’s interesting to compare this to the tobacco-causes-cancer “debate” from decades ago. Then, we had an overwhelming correlation of tobacco uses and various heart and lung diseases, but had not connected the dots to produce a perfect chain of cause-and-effect (and because not everyone who smokes gets cancer or heart disease, there is no certain chain of connected dots).
For global warming, we have an excellent connect-the-dots explanation for why adding greenhouse gasses to the atmosphere should warm the climate, though not every place will necessarily be warmer, nor will every year be warmer. What we lack, because the increase is so gradual and the weather so noisy, is a dead-to-rights correlation of climate change with increased CO2. There’s not going to be a perfect correlation between CO2 and temperature, because there are decade-long natural variations in the weather. There have been decades of low Atlantic hurricane activity, and decades of high Atlantic hurricane activity. El Nino and La Nina both affect the weather throughout North America. Other atmospheric changes — soot, haze, and aircraft-generated clouds — also affect the yearly weather.
There are certainly people who disagree with this, but arguments to the contrary have been plenty unconvincing. Seriously, Occam’s Razor. Increasing concentration of known GHGs, versus cosmic radiation and sunspots? An evil cabal of climate scientists and liberals, versus the coal and oil industries, who have a fiduciary responsibility to their shareholders to maximize profits? Can we have a little even-handedness in our so-called skepticism? And dire predictions of economic doom-and-gloom if we cut carbon — haven’t we heard these before? It wasn’t seat belts and emissions regulations that killed the US auto industry, it was their myopic fascination with monster trucks.
The most unfortunate fact, is that the US is unlikely to do much. Consider the metric system — we’re still not using it. Drills, torque wrenches, milk, all still oriented to the old units. And this didn’t require a very costly change, and in fact businesses (car manufacturers, for example) have often already converted. If we work to reduce greenhouse gas emissions, some non-trivial US industries will need to change, drastically. If we pursue the path of quickest and easiest reduction, we’ll eat less beef/pork, which means we will consume less corn. So, the beef, pork, and corn producers stand to lose, and will oppose it. If we drive smaller cars, and drive them less, and carpool more, then we will consume less gasoline — and the oil companies will lose, and they will oppose it. The less we drive, the more we carpool, the longer cars will last, so we will buy fewer cars. If we shift electrical production away from the fuels that produce the most greenhouse gasses, then the coal industry will lose, and they will oppose it.