The current international climate change conference in Montreal will conclude successfully if it produces a reasonable timetable for a post-Kyoto Protocol, the document guiding much of the world toward fewer greenhouse gas emissions. But even if that debate remains temporarily unresolved, the conference has already shown a widespread understanding of the human causes of climate change and a willingness to do something about it. This is fortunately true even within the most reluctant conference participant, the United States.

Representatives from U.S. states, cities and businesses are attending the conference, which runs through Dec. 9, because they can see the many climate changes and potential changes, from more intense weather to a shifting Gulf Stream to the increased spread of disease. States, especially those in the Northeast and on the West Coast, are acting to slow emission rates in the absence of federal action. The Northeast, for instance, is moving toward emissions cuts 10 percent below 1990 levels by 2020, something the Maine Legislature approved two years ago; California aims to reach 1990 levels by 2020.

Cities, many of them through the U.S. Mayors Climate Protection Agreement, are also working on climate protection. Businesses, which understand that greater energy efficiency often means lower cost, don’t want to be left behind their competitors in nations that are pushing new technologies.

All of this would be easier in the United States if the Bush administration stopped fiddling around with new ways to express inaction and at a minimum encouraged the states and cities that are acting responsibly in the face of mounting evidence. That seems unlikely, unfortunately, and others will answer the worldwide question of what happens post-Kyoto, in 2012.

A national policy is preferred because those policies tend to produce better enforcement and they reduce the chance of industries merely moving across state borders or states making gains at the expense of pollution levels in other states – outcomes called carbon leakage. An aggressive national policy is also a realistic response to a threat that becomes more apparent year by year.

Congress could help by passing serious cap-and-trade legislation that sets mandatory reductions over a reasonable time for industry. It could set much tougher rules for mobile sources of pollutants. Indeed, there is growing bipartisan consensus that such limits are both prudent and achievable. Passing them would certainly give the United States a better position from which to participate in the difficult global debate ahead on climate change.

Instead, Congress talks, the president obfuscates and the work is left to states and municipalities to work out. Think globally, act locally is a fine idea, but acting nationally would be a good idea too.