As I mentioned in a previous post, there are three central assertions being made by global-warming activists, each of which is contentious in its own right. The first — let’s call it W — is that the Earth is currently warming. The second — we’ll call this one A — is that W is caused primarily by anthropogenic influences, the corollary of which assumption is that by reducing or eliminating those influences, we can prevent significant warming. The third — call it R — is that W and A, taken together, justify a global political and economic response, an engineered reorganization of human affairs on a staggering and utterly unprecedented scope.
It is important to keep in mind that while W and A are empirical claims, having to to with facts about the actual world, R is a normative assertion; it is about what we ought to do. The “Climategate” kerfuffle that has provided such lively entertainment in recent weeks is about W, and to a lesser extent A, while R is irreducibly a matter of opinion — though of course one that depends very sensitively upon W and A. With me so far?
At the root of all of this Sturm und Drang, then, is the truth or falsity of W. Is the Earth actually warming? This is a central issue in the Climategate flap: obviously, if W is false, there is no crisis, and A and R become moot.
It may well be that the Earth is warming, though even this claim is controversial (and what would be amusing, if the stakes weren’t so high, is that all of this is rich not only in controversy but what I shall call meta-controversy: even the extent to which the claims of the various parties are controversial is itself controversial). My understanding had been that for the first years of this century, at least, there had been no warming at all, and perhaps some slight cooling. The Times published a story yesterday, however, about a new report declaring that the first decade of this century was indeed warmer than the last. (I’m sure there will be a good deal of back-and-forth about this, and I will be following it attentively.) Certainly it is fair to say that the naked-eye evidence seems to indicate that something is afoot with the world’s glaciers, permafrost, and ice sheets, though even that has been attributed by some to be the result of changing patterns of moisture, and not warming. But let’s assume, arguendo, that there is indeed some warming taking place.
Next comes A: is W primarily the result of anthropogenic influences? Note that the word “primarily” is key here; if any anthropogenic influence is dwarfed by natural processes, then an attempt to control W by moderating those influences is not likely to accomplish much.
If A is true, then it seems that W should be exceptional, because the conditions set forward for A — the Industrial Revolution, the use of fossil fuels, clearing of rainforests, and the various activities of modern civilization in general — are recent, and unique in the world’s history, and so could not have been the cause of any climate fluctuations in ancient times.
So how can we examine the historical record? Scientists have developed some very clever tools for this. One of them is the interpretation of ice cores taken from places that have lain under thick ice for thousands of years. Here’s how it’s done.
The ice in the Earth’s cold places is deposited as water precipitated from the atmosphere — water that had previously entered the atmosphere by evaporation from the Earth’s rivers, lakes, seas and oceans.
Water is a molecule that consists of three atoms: two of hydrogen and one of oxygen. Each of these atoms, in turn, comes in several forms, or isotopes, differing only in the number of neutrons. By far the commonest forms of each (for reasons having to do with stellar evolution) are oxygen-16 (16O), with 8 protons and 8 neutrons, and hydrogen-1 (1H), with one proton and no neutrons.
But there are other stable isotopes of oxygen and hydrogen as well, and a very small part of the world’s water molecules are made of these rare atoms. For hydrogen, there is an isotope 2H, called deuterium (often written as D); it has one extra neutron. And for oxygen, there are several, including 18O, which has two extra neutrons. Because these are all stable isotopes — they are not subject to spontaneous decay — the proportion of these atoms in the world’s water inventory is assumed to be constant.
Water molecules containing these exotic isotopes weigh more than ordinary water, but react chemically and electrostatically in exactly the same way, and this is what makes ice-core studies possible. Because of their additional mass, “heavy” water molecules are more reluctant to evaporate than ordinary water. But the warmer it gets, the more of them do in fact enter the atmosphere — and therefore, during warmer times more of them accumulate in the world’s ice sheets. So by examining the relative proportion of these isotopes in ice cores (which are striated in annual layers, like tree rings) we can read off historical changes in average global temperatures.
These data are publicly available; you can, for instance, download one such record here, courtesy of NOAA: a Greenland core that goes back several thousand years.
So: are we entering an unprecedented period of warming, or is it that the world simply warms and cools from time to time? If you look at the famous (or infamous, depending on your view) “hockey stick” graph, or get your information only from certain sources, you might think that the former is true.
This is almost certainly not the case, however, as we can see, for example, in this article from the Foresight Institute [hat tip: LA], which examines the ice-core record at the time-scale of thousands of years — still an eyeblink, in geological terms. What we see is what archaeologists and paleontologists have always known: that the Earth oscillates periodically between cold and “interglacial” periods, with warm spells like the one our species has enjoyed for the past few millennia — the entire span, in other words, of human history — being comparatively brief.
The author of the article, the nanotech expert J. Storrs Hall, points out that the present warming, such as it is, might well be seen as a return to the average, slightly warmer temperatures of our current interglacial period, after a recent dip often referred to as the “Little Ice Age“:
In fact, for the entire Holocene — the period over which, by some odd coincidence, humanity developed agriculture and civilization — the temperature has been higher than now, and the trend over the past 4000 years is a marked decline. From this perspective, it’s the LIA that was unusual, and the current warming trend simply represents a return to the mean. If it lasts.
Dr. Hall sums up:
In other words, we’re pretty lucky to be here during this rare, warm period in climate history. But the broader lesson is, climate doesn’t stand still. It doesn’t even stand still on the relatively constrained range of the last 10,000 years for more than about 10,000 years at a time.
Does this mean that CO2 isn’t a greenhouse gas? No.
Does it mean that it isn’t warming? No.
Does it mean that we shouldn’t develop clean, efficient technology that gets its energy elsewhere than burning fossil fuels? Of course not. We should do all those things for many reasons — but there’s plenty of time to do them the right way, by developing nanotech. (There’s plenty of money, too, but it’s all going to climate science at the moment. ) And that will be a very good thing to have done if we do fall back into an ice age, believe me.
For climate science it means that the Hockey Team climatologists’ insistence that human-emitted CO2 is the only thing that could account for the recent warming trend is probably poppycock.
So: if the points made here, and similar points being made by heretics elsewhere, are valid, then we have considerable reason to doubt the truth of A, even if we accept W. And if A — which, amongst Global Warmism’s priesthood and its millions of progressivist acolytes, has become the Reichstag fire that justifies an audacious bureaucratic takeover of the world’s economic enterprises, and forced redistribution of the wealth of great nations — is false, then R is revealed to be without any rational foundation.