Unlike Social Security debt, climate change is irreversible

On the Non-equivalence of Greenhouse Gases and Entitlement Spending

Paul Krugman, NYT

One fairly common trope in budget discussions - I'm pretty sure I've done it myself, somewhere along the line - is to compare attitudes toward fiscal issues and those toward environmental issues. The usual version, which I must have used, is to compare attitudes toward the long run: pointing out how strange it is that many people profess to be deeply concerned about the state of the Social Security trust fund in the year 2037, while being apparently indifferent to the state of the climate around the same time, which is all too likely to involve things like a permanent drought in the southwest and so on.

But can you make the analogy work in reverse, and say that liberals concerned about the future of the environment should be equally concerned about the long-run budget outlook? Tom Friedman recently made that argument, so it's worth pointing out, respectfully, why I disagree. And I think that explaining what's wrong here helps make the broader point that we are spending far too much time worrying about long-term budget projections.

So, let's start with climate change. Serious people are and should be deeply worried, indeed horrified, by the lack of action on greenhouse gases. But why? Why not just assume that when climate change becomes undeniable, we'll do whatever is necessary?

(More here.)