This afternoon, I finished reading an excellent new book: A Vast Machine: Computer Models, Climate Data and the Politics of Global Warming by Paul Edwards*. The book traces the intertwined histories of data and models of climate and the weather and the politics surrounding climate change. Edwards argues that the dichotomy data vs. models is nonsensical in the world of climate, because “without models, there are no data.” (p. xiii)
Edwards explains what he means by this statement through a historical analysis of the emergence of global climate data. Even contemporary weather data is derived from hundreds of different observations from different kinds of instruments that measure different physical quantities. To get from these recordings to “data”, i.e. what the weather looks like right now, requires complicated models that map from the things our instruments see to the physical quantities we care about.
For example, satellites cannot literally read the temperature of the Earth’s surface nor at any point in its atmosphere – instead they monitor the emissions coming out of the atmosphere and have to work backwards using carefully calibrated models to determine the surface and lower-level atmospheric temperatures associated with that radiation profile. Furthermore, our data about the climate are radically incomplete up to the recent past, and older observations must be made consistent with more recent observations using different standards (for example – how do you calculate the daily average temperature? Measure once an hour? 3 times a day? Etc.), different instruments, different locations, etc. And all of that happens before the models predicting what will happen next – the models that map from the data (already modeled) to predictions about the future. Thus, Edwards suggests some of our current debates about global warming (“sound science”, data vs. models, etc.) is misguided or worse.
I won’t try to explain the complexities of the book any more than that. It’s very rich, and if you are interested in how we know what we know about climate change, or the history of computers and data, or in reading a really good example of contemporary science studies, read the book!** But I do want to note one paragraph that caught my eye. Edwards discusses shifts in the certainty of scientists about the reality of global warming and its anthropogenic causes. He notes that one high profile scientist, James Hansen of NASA, asserted in 1988 before the House Energy Committee “99 percent” certainty that greenhouse gases were producing unusually warm temperatures in the 1980s. Hansen was a bit ahead of the scientific consensus, but the moment was important for raising the profile of the issue. Thus, Edwards notes:
Though many climate scientists disagreed with Hansen’s “99 percent” level of certainty, his testimony is widely regarded as the moment when global warming entered mass politics. From that point forward, the issue received substantial, high-profile coverage in the American press. By 1990, awareness of the issue among the American public had shot up to around 75 percent – a high figure for almost any non-economic issue in the United States. (p. 391)
What I want to interrogate here is the idea of global warming as a “non-economic issue”. In one sense, global warming is clearly an issue about Science!, and thus quite far from the realm of money. That is, the question ‘does the emission of CO2 from the burning of fossil fuels contribute to an increase in global average temperatures?’*** is not one economists have much say in or should have much say in. On the other hand, “global warming” as an issue isn’t just about whether or not global temperatures are rising, and whether or not those temperature rises are anthropogenic. It’s also about what will happen when temperatures do rise, and what we can and should do to prevent those rises. And that’s where the “non-economic” label gets sticky.
For example, how bad will a 3°C rise in global average temperatures be? Climate models can help us figure out how much the sea level will go up, or how the seasons will change in Northern Europe, or how precipitation will change over the Sahara. But how bad will that all be? For that we need some sort of measure of damage, of costs to people. There are a lot of options, but one obvious choice (given the way the world sees things nowadays) is about money. How much will it cost to build bigger levies, to move displaced persons, to deal with more hurricanes, and so on? If global warming were entirely a “non-economic” issue, it almost definitionally couldn’t be as important an issue as it is – the economy includes too much of what we care about. Not only the likely costs of abating the rise in greenhouse gases (from switching to alternative energy sources), but also the benefits (in terms of not having all those bad things above happen) are being made into economic questions in order to be debated and solved. Hence the growth of the field of environmental economics, and the reemergence of key concepts like externalities and Pigouvian taxes. Indeed, one of the biggest debates around how to solve climate change concerns the relative merits of “cap and trade” vs. “carbon taxes” as methods for reducing greenhouse gas emissions, and economists are leading figures in this debate (e.g. Mankiw’s Pigou Club above, see also MacKenzie 2009: chapter 7).
So, is Global Warming a non-economic issue? I guess that depends – depends on the context, depends on the year, and depends on the actors that are trying to construct or reconstruct the issue for their own purposes (benign or otherwise). It’s certainly an economic issue for the coal companies who have organized to try and promote scientific controversy in the face of unequivocal agreement on the basic facts (cf. Oreskes 2004). But it’s a scientific issue, a moral issue, a political issue, and so on. I think that’s one reason why it’s become so prominent – it strikes at the core of how we function, the basic infrastructure we use in our daily lives (e.g. energy production), and it demands that we act in a massive way under considerable (though diminishing) uncertainty about what exactly is happening, in ways that reflect our commitments not just to ourselves (individually or nationally), but to our collective posterity.
* Full disclosure: Paul Edwards is a professor at Michigan and one of the directors of the Science Studies Certificate program in which I am a student.
** For those who want to get something out of it without slogging through 440 pages about thermometers and satellites, Edwards provides a handy “How To Read This Book” section that suggests which chapters to read for different kinds of audiences. I think any author writing a book this long or longer should consider adding such helpful hints!
*** Hint: The answer is, “Yes.”