At least to my mind, last week was extremely significant. Last week, George W. Bush for the first time believably acknowledged that human beings are the principal cause of global warming.

Now, I know, I know: There are a few instances from the past where if you listen really, really closely, Bush sorta kinda said as much. But then he would come out and say something else different and contradictory–or Dick Cheney would. Or Bush would get revealed to have gotten his science advice from Michael Crichton. Or we’d see more interference with climate scientists by the administration. Anyways, something would always happen to make you slide the administration right back into the “skeptic”/denialist camp again.

Not any more, though. I now believe it: Bush accepts the scientific consensus. But he’s still unacceptably tardy in doing so, and has probably gambled the whole planet in the process. His behavior is still unforgivable.

The administration seems to have two ways of explaining why Bush has only come around now about the science, as opposed to doing the right thing and acknowledging it up front when Bush first took office. Neither excuse holds water.

The first is the argument that Bush hasn’t come around at all, because he always accepted the scientific consensus on global warming. Or as a White House letter put it earlier this year: “Beginning in June 2001, President Bush has consistently acknowledged climate change is occurring and humans are contributing to the problem.”

This assertion depends upon some clever rewriting of history. During his June 2001 Rose Garden speech, Bush did not say forthrightly that humans were causing global warming. Rather, he said we were causing an increase in atmospheric greenhouse gas concentrations, but carefully avoided acknowledging the central causal link between those emissions and the global warming trend.

Members of the administration have gone so far as to misquote the president himself in order to make it seem like he was in line with the science in 2001, but the attempt doesn’t stand up to any intellectually serious scrutiny.

Second comes the argument that the scientific consensus now is stronger than it was when Bush came into office, and that’s why the president is now accepting to it. Or as the president himself now put it late last week: “Our understanding of climate change has come a long way. A report issued earlier this year by the U.N. Intergovernmental Panel on Climate Change concluded both that global temperatures are rising and that this is caused largely by human activities.”

Bush is being deceptive here. It’s true that over the past six years, scientists have indeed gone from “likely” to “very likely” in terms of ascribing a certainty level to the conclusion that humans are driving global warming. Such is scientific progress.

However, Bush could just as easily have acknowledged that “global temperatures are rising and…this is caused largely by human activities” in 2001. The 2001 IPCC report–released prior to his Rose Garden speech–stated plainly that “most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations.” What’s more, when the administration asked the National Academy of Sciences whether the IPCC was right, the NAS quickly fired back with an analysis stating: “Greenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise. Temperatures are, in fact, rising. The changes observed over the last several decades are likely mostly due to human activities…”

Bush also had this report in hand in time for the Rose Garden speech in 2001.

The truth is that whether scientists are giving you 2/3 odds (“likely,” 2001) or 9/10 odds (“very likely,” 2007) that something bad is happening, it’s silly to just wait for more proof to come in–especially when that something bad is going to become something worse if you’re dilatory. Once again, then, the argument for taking global warming seriously was as strong in 2001 as it is in late 2007.

Granted, the administration might argue back that at least on his own terms, Bush has been consistent. The president has always defined global warming as a “problem” to be addressed, after all, and has always proposed more or less the same strategy for addressing it: more research combined with voluntary action. Is my disagreement with Bush’s record therefore merely at the level of policy, rather than at the level of science?

I don’t think so. If Bush always defined global warming as a problem, and always had a “policy” for dealing with it, my sense is that was more about having something to say and point to whenever the inevitable questions arose from the media (which happened far too infrequently in any event). But if you’re serious about an issue, you don’t meddle with the science in the way the administration repeatedly did. You don’t act as if you have something to hide, as the administration repeatedly did.

Many others will tell you that even if Bush now accepts the science, he isn’t contributing helpfully to the policy mess anyway with his continuing insistence on voluntary action to address global warming. I certainly don’t disagree. But if that’s not what I choose to emphasize, it’s for this reason: I still can’t get over the dishonest, wrongheaded, and frankly immature behavior of this administration over the past six years regarding climate science. Bush’s concession now only seals the case: He has been a deeply and disastrously irresponsible president.

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