Friday, December 11, 2009

more on climategate

I am fearfully and wonderfully made, the Psalmist wrote. The same thing can be said for any scientific theory. Far more convincing than the ‘fact’ that there is a scientific consensus on global warming is the fact that the literature on the measures and mechanisms of climate has become global itself over the last thirty years, and is in that stage in which numbers of models are thrown up to address the thousand and one anomalies suggested by the data flow. Climatology and its provinces – climate botany, mineralogy, hydrology, physics – is really a subordinate to earth system science. And we are watching its rich period, when multiple climate ‘objects’ are constructed. Although I am not happy with the common ‘construction’ word, with the implication of human agency and intention, for it doesn’t quite stretch far enough to tell us how these objects appear, often quite unexpectedly. I am fearfully and wonderfully made, but my runny nose isn’t – its an unexpected result of the making. And thus we may speak of all constructed objects with this precaution, which is that they tend to construct in turn.

Out of all that information, picking out a trend in global climate, if there is one, has been no mean task. One of the things that separates the denialist cult from the science of climatology has been the refusal to assess this vast amount of data in scientific terms – looking for links, explanations, tendencies. Rather, it is dealt with on the level of a political issue, period. This is why Easterly’s blog post was such an exercise in charlatanism, from the oozy intro of Crook to the foreshortened and ignorant reference to the Wegman committee to the completely comic ‘shock’ expressed by the idea that one group of scientists would try to suppress the views of another – comic because Easterly’s discipline, economics, is notorious for such things. I have no need to go into the Cowles commission – one merely has to point to the experience of Card and Krueger, economists whose data suggest that the minimum wage doesn’t cause unemployment, a sacred canon among the neo-classicals, and the backlash against the two. Here’s a taste of the rhetoric Krueger stirs up, from something called the Economics Policy Journal blog:

“Alan B. Krueger is co-author with David Card of Myth and Measurement . Somehow in this book, they manage to throw overboard the law of supply and demand, to reach the conclusion that "the claim, that a higher minimum wage cuts jobs, lacks support."

At one point, they report among a number of "main empirical findings" that (page 3):
Increases in the minimum wage also generate a "ripple effect", leading to pay raises for workers who previously earned wages above the minimum wage.
It is difficult to understand how Card and Krueger can even be considered economists with such beliefs. If one does not believe in the law of supply and demand for the labor market, can one believe in the law of supply and demand, at all, for any market?”

I can’t imagine, say, Chicago School economist John Cochrane disagreeing with that. If the empirical evidence goes against the theory, in economics – throw out the evidence.

However, basta, I have other fish to fry in this post. I want to show how the evidence for climate change – Global Warming, to give it the press name - relates to the general framework of climatology.

From a common sense perspective, the argument for global warming is not problematic. That is, we have every reason to expect that an increase in greenhouse gases in the atmosphere (for instance, CO2), in the absence of any organic or earth systems means to capture or recycle that increase, will have an effect on the atmosphere and ultimately on the globe proportionate to its chemical and energetic nature. The Superfreakonomics guys failed to understand this elementary fact, although they quote with approval the man who most clearly sketched it out, Ken Caldeira. Here’s a pertinent quote, from John O’Donnell, formerly of Princeton’s Plasma Physics lab, now a VP for a Solar energy company, reprising the Caldeira presentation regarding Carbon Dioxide:

…each molecule of CO2 released thermal energy when it was formed — that’s why we formed it. In the case of electricity generation, about 1/3 of its thermal energy went out a wire as electric power, the rest was released promptly as waste heat. But each molecule of CO2, during its subsequent lifetime in the atmosphere, traps 100,000 times more heat than was released during its formation.”

Thus, from a common sense view, CO2 would seem as likely to warm the earth as starting a fire in your fireplace is likely to warm your living room. Or, indeed, as the gasoline in your combustion engine is likely to run the car.

But the common sense view does not take in the great feedback system that takes that greenhouse gas, and others, out of the atmosphere. Throwing in a complex set of negative and positive feedbacks (the latter being things like, the more water warms, the less it can absorb CO2, and the former being things like, the more CO2, the richer the leafage of certain plants), common sense only gets us as far as a hypothesis. [For an overview of simulations of CO2 increases in the atmosphere, see Multicentury Changes to the Global Climate and Carbon Cycle: Results from a Coupled Climate and Carbon Cycle Model by G. BALA, K. CALDEIRA, A. MIRIN, AND M. WICKETT in Journal of Climate, November 2005.]

It is important to note, here, that the denialist case has to deal with the common sense framework, too. Either they have to show that the CO2 is somehow absorbed, or that its energetic effects are blunted, or that the capacity of the earth system is such that the increase in thermal energy is a wash.

Now, given this starting point, one wants to get a crude sense of the history of the system – the system of climate. In fact, we have only a very tiny sample of the earth’s climate to go on – good continuous records of air temperature don’t go back very far, at most, in some places in England and France, 200 or so years. Reconstructing the climate over the last 4 billion years is, then, a matter of a great deal of deductive work. One needs clues. One of those clues is, indeed, the mix of gases in the atmosphere, which is why ice cores from Greenland, the Arctic and Antarctica are so important to climatology. Here we bump into a fact that seems to be unappreciated in the popular discussion of global warming – when we quote the scientists about past climates, we are quoting theories that depend on our knowledge of the present climate system. In other words, assumptions about the effects of greenhouse gases are implicit in these past climate projections. Thus, we ‘know’ that there was a temperate spike in the Eocene – the Paleocene-Eocene thermal maximum – because we read the evidence with the same tools that are now being applied to the present climate. We’ve taken drillings from the ocean floor and analyzed them “through measurement of stable oxygen isotopes”. [Huber, McCleod, Wing, 198] And after the hypothesis of a massive and sudden increase in the temperature of the oceans, scientists looked around for causes and found evidence for a massive release of… a greenhouse gas. Methane. The gas that is trapped, by the way, in the tundra, which at the moment is, according to every reasonable ground temperature measurement, warming up considerably – in geological time, the warming is split second.

Thus, it looks like the denialist position not just go against the scientific ‘consensus’ – it must present a different picture of climate patterns in as much as those patterns are consistent with and read by our current climatology paradigm. It can get around this task by claiming that, a, the statistical models used to put together disparate weather data into trends is flawed, or b, by citing counter evidence that would show, for instance, that the CO2 is not having the effect that is being claimed for it.

You’ll note I’ve left out of account the whole anthrogenic vs. sunspot controversy. I leave it out because it is based on a misreading of the global warming claim. That claim is primarily about the increase in CO2 and its effects, and secondarily about the source of that increase. The climate can warm or cool without anthrogenic intervention. This has been picked up by denialists, curiously enough, as some superargument. Here we leave science per se, and enter the realms of social pathologies, where the argument is really about blame and honor. I love to blame my own self – one of my favorite things – but this counts for little in the controversy thus far.

No comments: