Advocates of tighter governmental rules to curb the human causes of climate change can draw at least three lessons from a recent announcement that some major corporations have teamed up with environmental groups to demand caps on the production of carbon dioxide. They are lessons Congress should follow closely.

The corporations are Alcoa, Caterpillar, DuPont and General Electric, joined by BP, Duke Energy, FPL, Lehman Bros., PG&E and PNM Resources. Their partners are Environmental Defense, Natural Resources Defense Council, Pew Center on Global Climate Change and World Resources Institute. The groups agreed to call on Washington to produce a cap-and-trade system for carbon emissions that would lead to reductions of 10 to 30 percent over the next 15 years.

One of the reasons the corporations say they are urging Congress to act is that they fear states devising their own standards, creating dozens of different sets of rules with dozens of advocacy groups pushing for even tougher standards to make their lives miserable and perhaps unprofitable. A federal standard would be more predictable and a fight to prevent it from being raised would be simpler.

Still, when doubters point out that state rules don’t do much to reduce pollution nationally, one response is that they get the attention of those being regulated.

Politics have changed at the state level because the public has come to accept what the vast majority of scientists and large majority of politicians, including those in the Bush administration, accept: that human-generated pollution is changing the climate and this will result in harmful consequences that will likely outweigh any positive ones. The corporations understand the public will accept and even encourage government action on this issue; the question is how severe the coming regulation will be.

Having lost a Republican majority in Congress, those who want as few climate-change regulations as possible are now counting on President Bush. But even there, they will find movement toward curbing greenhouse gases, including some mild reforms proposed Tuesday in the State of the Union address among encouragement for alternative fuels. According to the Wall Street Journal, DuPont believes tougher regulations will raise demand for energy-efficiency products and the utility Entergy Corp. could benefit from a fuel-mix that includes low-carbon fuels.

The demand for Congress to set cap-and-trade standards is meaningful only if the cap is tough enough to make a substantial reduction in carbon dioxide emissions. The levels agreed to by the corporations aren’t there yet, but they are a start. Congress should be interested in pushing them forward now under a fairly short time frame and thinking long-term about tightening them further.