Environmental economics : Which model? Who cares?

Extrait de: Environmental economics : Which model? Who cares?, The Economist, Mar 16th 2011,

CLINKING along within the background noise of the wonkosphere in recent years has been an ongoing debate between environmental policy experts and economists over how society should approach climate policy.

The feud has turned bitter at times, as the environmentalists have grown increasingly frantic about the signals their data are sending them while economists continue to council a moderate approach, based on the idea that economies tend to grow and are quite adaptive. This is a bit of an oversimplification: within economics there are serious debates over how to model the dispiriting array of unknowns involved in climate scenarios. How, for instance, should one go about predicting the impact of large-scale climate migration on global trade at a point fifty years down the road? It's hard stuff, but important stuff.

Brad Johnson, of the Centre for American Progress, spoke to economist Lord Stern about one particular disagreement, namely, the rightness or wrongness of the Congressional Budget Office's assessment of likely climate costs. Have a look


Mr Johnson posts the video, then goes on to slam economists generally, including Lord Stern, who "consistently underestimate[s] the consequences of climate change".

Personally, I don't find this to be a particularly helpful approach to the debate, for several reasons. In my view, climate economists are working to find the right approach to what are, let me reiterate, very difficult questions. I think it's possible—indeed, likely—that current models are failing to adequately capture the impact of climate change on the global economy. But this is how science works. You approximate reality poorly, then you learn from that and do a better job, and then you do a better job still. Current research in the economics of climate change is a discussion about how to treat all the variables involved.

Now, environmentalists argue that, that aside, economists are putting us all at risk by opining beyond their models in unhelpful ways on the country's op-ed pages and by assuring policymakers that, for example, a lower carbon tax is acceptable.

To this I say, first, that individual economists are not equivalent to "economists". Second, as I've argued before, economists are very bad at getting policymakers to believe what they say when what they say goes against the interest of powerful entities. And third, economists are clearly not the bottleneck to action.

Most economists, as best I can tell, support policy action to reduce emissions. Republicans in the House of Representatives, on the other hand, are almost uniformly in denial that climate change is even a real problem. The debate in Washington is so drastically out of step with the discussion among scientists and economists that it would be funny if it weren't terribly tragic.

Environmentalists and economists are fundamentally on the same side, supporting the use of data and the scientific method to reach reasonable, peer-reviewed conclusions and appropriate policy recommendations. Their differences are nothing in comparison to the gulf between those who prefer that peer-reviewed research inform a policy debate and those who'd rather cite email forwards. Until a way can be found to convince deniers to appreciate the reality of the situation, inter-disciplinary bickering is mostly a waste of time.