Last week began with a Supreme Court decision declaring that the federal government had the authority to regulate greenhouse gas emissions and all but ordering the Bush administration to do so. It ended with a report from the Intergovernmental Panel on Climate Change — the world’s authoritative voice on global warming — warning that failure to contain these emissions will have disastrous environmental effects, especially in poorer countries, which are least able to defend themselves and their people against the consequences of climate change.

One would hope that these events would shake President Bush out of his state of denial and add his authority to the chorus of governors, legislators and business leaders calling for an aggressive regulatory and technological response to the dangers of global warming. They haven’t. When asked about the Supreme Court decision, the president said he thought he was already doing enough.

He argued further that there was little point in the United States’ doing any more unless other polluters like China acted as well. That ignores the reality that no developing country is going to move unless the United States — which produces one-fourth of the world’s emissions with only 5 percent of its population — takes the lead.

The report from the intergovernmental panel was the second of three due this year. The first concluded with “90 percent certainty” that humans had caused the rise in atmospheric temperatures over the last half-century. The most recent focused on the consequences, few of them positive.