What do we want from Copenhagen?

The huge scientific uncertainty about the cost of inaction has obscured a surprisingly strong economic consensus about the economic cost of stabilising global CO2 concentrations at the levels currently being debated by national governments, that is, in the range 450-550 ppm. The typical estimate of costs is 2 per cent of global income, plus or minus 2 per cent. There are no credible estimates above 5 per cent, and I don't think any serious economist believes in a value below zero (that is, a claim that we could eliminate most CO2 emissions using only 'no regrets' policies).

For anyone who, like me, is confident that the expected costs of doing nothing about emissions, relative to stabilisation, are well above 5 per cent of global income that makes the basic choice an easy one. Any agreement that comes out of Copenhagen or its successors will be better than no agreement.

Follow the link to Crooked Timber to read the whole thing.