The Lieberman-Warner Climate Security Act (CSA) will reach the Senate floor this week -- the first climate bill to do so in three years -- and the Tribune editorial board gives its cautious endorsement today:

No one expects the Warner-Lieberman bill to become law this year. But next year could be a different story. All three of the major party presidential candidates have expressed support for a carbon cap-and-trade program. This is an enormously complex bill that still needs work to make sure its benefits outweigh its burdens. But it is on the right track.

For a valuable overview of the bill and its prospects for passage, check out Kate Sheppard's comprehensive primer at Grist. The bill itself is relatively weak -- the emissions targets fall short of the levels advocated by the Intergovernmental Panel on Climate Change and $3.4 trillion worth of carbon credits would be distributed to polluting industries. It also stands no chance of passage, given President Bush's hostility to a mandatory emissions cap.

But it sets the stage for 2009: Barack Obama has already signaled that alternative energy legislation would be one of his first priorities and an expanded Democratic Senate majority -- including renowned conservationists like the Udall cousins -- would give hope to enviromentalists desperate for action. Sen. Barbara Boxer (D-CA) agrees:

No matter how it all turns out, serious deliberation of climate legislation is itself a sign of progress.

"We have to start the debate, and this is a very good place to start it," said Boxer. "We may well pass a very good bill, we may get derailed. But however far we take it, it's very important to start now. Landmark bills don't pass in a day or a week."