The answer is, the usual suspects: greed and cowardice.

Paul Krugman on the Senate and House Climate Bills failure, in the NYT.

He goes on to identify the cowards:

``There are a number of such climate cowards, but let me single out one in particular: Senator John McCain.

There was a time when Mr. McCain was considered a friend of the environment. Back in 2003 he burnished his maverick image by co-sponsoring legislation that would have created a cap-and-trade system for greenhouse gas emissions. He reaffirmed support for such a system during his presidential campaign, and things might look very different now if he had continued to back climate action once his opponent was in the White House. But he didn’t — and it’s hard to see his switch as anything other than the act of a man willing to sacrifice his principles, and humanity’s future, for the sake of a few years added to his political career.

Alas, Mr. McCain wasn’t alone; and there will be no climate bill. Greed, aided by cowardice, has triumphed. And the whole world will pay the price.''