torsdag, januar 04, 2007

Delong fortsætter med at se klart på global opvarmning

Delong forklarer overbevisende hvorfor man enten skal gøre noget ved global opvarmning eller gøre noget ved global fattigdom, set ud fra en logisk synsvinkel. Man kan nemt forstille sig at gøre begge ting samtidig også.

Money quote:

"The Australian economist John Quiggin has an illuminating discussion on his website ( ) that comes down on the side of a $0.50/gallon tax, because he projects that spending today to reduce carbon emissions is a good investment for the future. Assuming that annual per capita income grows at about 2% per year worldwide, a marginal expenditure of roughly $70 today to cut carbon emissions would be worth it if, accounting for damage from global warming and adjustment costs, the world of 2100 would be $500 richer in year-2006 purchasing power.

On the other hand, critics point out that the world today is poor: average annual GDP per capita at purchasing power parity is roughly $7,000. We expect improved technology and its spread to make the world of 2100, at a 2% annual growth rate, much richer: $50,000 per capita of year-2006 purchasing power. So the critics argue that we need the marginal $70 per capita today much more than the richer people of 2100 will need the $500 that they would gain from being spared the effects of global climate change.

But what the critics often don’t say is that the same logic applies to the world today. Average annual per capita incomes in the US, Japan, and Western Europe are currently around $40,000, and less than $6,000 for the poorer half of the world’s population. The same logic that says we need our $70 more than the people of 2100 need an extra $500 dictates that we should tax the world’s rich more, as long as each extra $500 in first-world taxes generates as little as an extra $70 in poor countries per capita incomes.

In short, if the world’s rich are stingy today toward our much richer descendants, and if we want to leave our environmental mess to them to deal with, we should be lavish toward the world’s poor. Likewise, if we are stingy today toward the world’s poor, we should be lavish toward our descendents."