Krugman warned that if we take no action, in the form of regulations and higher taxes, then by the year 2100 "sea levels would rise" and "coastal flooding, already a major source of natural disasters, would become much more frequent and severe." The modern-day Jeremiah howled that "utter catastrophe does look like a realistic possibility."
If you listen to climate scientists - and despite the relentless campaign to discredit their work, you should - it is long past time to do something about emissions of carbon dioxide and other greenhouse gases. If we continue with business as usual, they say, we are facing a rise in global temperatures that will be little short of apocalyptic. And to avoid that apocalypse, we have to wean our economy from the use of fossil fuels, coal above all.
But is it possible to make drastic cuts in greenhouse-gas emissions without destroying our economy?
Like the debate over climate change itself, the debate over climate economics looks very different from the inside than it often does in popular media. The casual reader might have the impression that there are real doubts about whether emissions can be reduced without inflicting severe damage on the economy. In fact, once you filter out the noise generated by special-interest groups, you discover that there is widespread agreement among environmental economists that a market-based program to deal with the threat of climate change - one that limits carbon emissions by putting a price on them - can achieve large results at modest, though not trivial, cost. There is, however, much less agreement on how fast we should move, whether major conservation efforts should start almost immediately or be gradually increased over the course of many decades.
Krugman, in his usual pompous manner, presents as fact what is just liberal conjecture, especially "if you look at the evidence the right way" (?)
This is an article on climate economics, not climate science. But before we get to the economics, it's worth establishing three things about the state of the scientific debate.
The first is that the planet is indeed warming. Weather fluctuates, and as a consequence it's easy enough to point to an unusually warm year in the recent past, note that it's cooler now and claim, "See, the planet is getting cooler, not warmer!" But if you look at the evidence the right way - taking averages over periods long enough to smooth out the fluctuations - the upward trend is unmistakable: each successive decade since the 1970s has been warmer than the one before.
Second, climate models predicted this well in advance, even getting the magnitude of the temperature rise roughly right. While it's relatively easy to cook up an analysis that matches known data, it is much harder to create a model that accurately forecasts the future. So the fact that climate modelers more than 20 years ago successfully predicted the subsequent global warming gives them enormous credibility.
Yet that's not the conclusion you might draw from the many media reports that have focused on matters like hacked e-mail and climate scientists' talking about a "trick" to "hide" an anomalous decline in one data series or expressing their wish to see papers by climate skeptics kept out of research reviews. The truth, however, is that the supposed scandals evaporate on closer examination, revealing only that climate researchers are human beings, too. Yes, scientists try to make their results stand out, but no data were suppressed. Yes, scientists dislike it when work that they think deliberately obfuscates the issues gets published. What else is new? Nothing suggests that there should not continue to be strong support for climate research.
And this brings me to my third point: models based on this research indicate that if we continue adding greenhouse gases to the atmosphere as we have, we will eventually face drastic changes in the climate. Let's be clear. We're not talking about a few more hot days in the summer and a bit less snow in the winter; we're talking about massively disruptive events, like the transformation of the Southwestern United States into a permanent dust bowl over the next few decades.
Krugman warned that climate models were getting more pessimistic (never mind that those same models failed to predict the earth's current cooling trend):
At this point, the projections of climate change, assuming we continue business as usual, cluster around an estimate that average temperatures will be about 9 degrees Fahrenheit higher in 2100 than they were in 2000. That's a lot - equivalent to the difference in average temperatures between New York and central Mississippi. Such a huge change would have to be highly disruptive. And the troubles would not stop there: temperatures would continue to rise.
Furthermore, changes in average temperature will by no means be the whole story. Precipitation patterns will change, with some regions getting much wetter and others much drier. Many modelers also predict more intense storms. Sea levels would rise, with the impact intensified by those storms: coastal flooding, already a major source of natural disasters, would become much more frequent and severe. And there might be drastic changes in the climate of some regions as ocean currents shift. It's always worth bearing in mind that London is at the same latitude as Labrador; without the Gulf Stream, Western Europe would be barely habitable.
Krugman turned up the volume:
You might think that this uncertainty weakens the case for action, but it actually strengthens it. As Harvard's Martin Weitzman has argued in several influential papers, if there is a significant chance of utter catastrophe, that chance - rather than what is most likely to happen - should dominate cost-benefit calculations. And utter catastrophe does look like a realistic possibility, even if it is not the most likely outcome.
Weitzman argues - and I agree - that this risk of catastrophe, rather than the details of cost-benefit calculations, makes the most powerful case for strong climate policy. Current projections of global warming in the absence of action are just too close to the kinds of numbers associated with doomsday scenarios. It would be irresponsible - it's tempting to say criminally irresponsible - not to step back from what could all too easily turn out to be the edge of a cliff.