Global Warming, con't
By Arnold Kling
Three top climate researchers claim that the greenhouse gases already in the atmosphere should have warmed the world more than they have. The reason they have not, they say, is that the warming is being masked by sun-blocking smoke, dust and other polluting particles put into the air by human activity.
But they warn that in future this protection will lessen due to controls on pollution. Their best guess is that, as the mask is removed, temperatures will warm by at least 6°C by 2100. That is substantially above the current predictions of 1.5 to 4.5°C.
This makes more sense to me than the consensus forecast. As I pointed out in previous posts, human activity has grown exponentially over the past century, yet the consensus model of global warming is approximately linear–going backward as well as forward.
To me, this is bizarre. I think it’s fairly common to have a linear treatment variable and a linear response variable. I think it’s fairly common to have exponential treatment and exponential response. And I think it’s even common to have linear treatment and exponential response. But exponential treatment and linear response?
The only example I can come up with is an economic example–diminishing returns. You could have exponentially increasing labor on a plot of land, and only linear increases in output. But why should the human impact on climate exhibit diminishing returns–that is, the more we spew into the air, the less effect our spewing has?
Instead of a consensus around a linear forecast, it seems to me that we should have divergence involving various nonlinear forecasts. Maybe that sort of divergence would confuse the general public. But it would make more sense to me!