The $2 trillion question – 29 March 2012, The Economist

PUTTING a price on something that is priceless is, well, tricky. It is, however, possible to assign a number to how much damage is being done to that thing. In the case of the oceans, a conservative estimate of the cost of climate change is that by the year 2100 it will amount to nearly $2 trillion annually in 2010 dollars, or about 0.4% of global GDP. Any number that purports to describe an economy nine decades hence must be taken with a dollop of salt, of course. But it should not be dismissed out of hand.