Climate Change and Global Warming

Southern Man notes that the "Global Warming" crowd has dropped that verbiage and instead adopted "Climate Change" as though the two terms meant the same thing, to the point that (for example) The LA Times will no longer print letters from "climate change deniers." This is, rather transparently, a straw man argument: take someone who has legitimate doubts about the science of global warming (disclaimer: Southern Man would be one of those, for good solid scientific reasons) and accuse them of something entirely different. So today there will be a brief lecture on climate change.

The first thing to note is that the climate is always changing.

Temperature variations over the last half-million years. Graph copied from Wikipedia.

The long-term picture of the history of climate change is lengthy ice ages, lasting a hundred thousand years or so, punctuated by relatively brief interglacials that last ten thousand years or so. The current interglacial is called the Holocene. It is during this relatively brief time that humans, which have been around for longer than the duration of this graph, finally created civilization. The Holocene has been very, very good to us.

And there is the reason for Southern Man's disdain for Global Warming alarmists. We are a warm-weather species. We like warm weather. Put another way: a few degrees of Global Warming and many are inconvenienced. A few degrees of Global Cooling and billions starve to death. The suffering during the Maunder Minimum and the Little Ice Age weren't due as much to freezing as to widespread crop failures. Warm is good. Cold is bad.

The graph above is the most important player in long-term climate. We see the regular cycle of lengthy ice ages and brief interglacials and note that the Holocene, statistically, is nearing its end; indeed, the Holocene Climate Optimum was several thousand years ago. We do not know why the climate cycles in this fashion. There are some tantalizing correlations (the best candidate being the Malankovich Cycles) but no firm causation, yet. So there's an indicator that we're on the verge of long term cooling, just as everyone thought back when Southern Lad was in high school. He does note that the Nuclear Winter hypothesis has been largely discredited; we did the experiment (the USA and USSR detonated enough bombs during Cold War weapons testing to simulate a fair-sized nuclear war) and there was no discernible impact on short-term climate.

But there's another player and that's those pesky newly-civilized humans who contributed a thousand years of widespread deforestation and a couple of centuries of extensive use of fossil fuels, both of which have created a dramatic increase in atmospheric carbon dioxide. Now, while atmospheric CO₂ has been higher in the past the climate pot has never been stirred quite like this and no one knows what effect that will have. And by "no one" Southern Man includes climate scientists. But let's give this one to the Global Warming folks and say that this is an indicator of increasing temperatures.

The third, and probably most minor player, is solar activity. The Maunder Minimum and other local cooling trends have been correlated with low sunspot activity but again there is no guarantee of causation. Solar scientists agree that the sun is entering a period of relative inactivity. Southern Man will call that one a weak indicator of cooling.

But the Sun will win this game in the end; solar output increases by about 10% per billion years and in a few billion years or so the Sun will be hot enough to boil away the oceans and we will have either all died or evacuated the planet well before then. On the long term, Global Warming Baking is inevitable and it'll happen long before the Sun swells into an Earth-devouring Red Giant.

But what about in the short (as in next few centuries) term? We have two strong indicators, one of cooling and one of warming, plus (if you want to include it) a weak indicator of cooling. Perhaps they will offset. Again, no one knows. And, again, Southern Man isn't much concerned about Global Warming; Southern State will actually become more humid and temperate, with less extreme summers and winters, and he won't complain about that. Global Cooling, however, is a cause for concern and something he keeps in mind as he continues to build his little retreat out at The Land.