Given the sheer number of candidates for “worst legacy of the Bush years,” it may seem perverse to pick the hundreds of coal-fired power plants that have opened across China during his administration. But given their cumulative effect — quite possibly the concrete block that broke the climate-camel’s already straining back — I think they may be what history someday seizes on. And they are emblematic of George W. Bush’s utter failure to help the world rein in carbon emissions at what may have been the last possible moment.

When Bush first took office, China (and really India as well) were right at the bottom of their energy takeoff. China had actually become steadily more energy efficient over the previous decade, as absurd state industries began to shut down. But both countries were poised, thanks to the creation of the World Trade Organization, for the true explosion of their export economies, and for the subsequent rapid migration of rural residents to the factory cities that became the largest exodus in human history.

The obvious, easy, and cheap candidate to power that boom was always going to be coal: China has its own vast stockpiles and the kind of labor force and rail links to make exploiting it relatively easy. But by 2000 we already knew enough to conclude just how dangerous it would be if China went whole-hog into the coal business. George W., remember, had pledged during the 2000 campaign that he would enact a “four-pollutant bill” for America’s own coal-fired power plants, forcing them to start reducing carbon dioxide.

But Bush abandoned that plan within weeks of taking office, kneecapping Christine Todd Whitman, his EPA chief, just before her first foreign trip. She grinned and took it, and the rest of the world winced and took it. From that day forward there was no real chance that the world would make substantive progress against carbon during the Bush years.

For one thing, the lack of U.S. action provided everybody else who didn’t want to change with a perfect scapegoat, an unbeatable excuse for doing nothing. The Chinese, for instance, could say with perfect justice that they certainly shouldn’t have to take the lead — because they’ve been burning fossil fuel only a short time, it will be decades before they’re as responsible for global warming as the U.S., never mind their much higher population. (Not only that, of course, but a huge percentage of the Chinese emissions come from building stuff for us, now that we’ve gutted our manufacturing economy.)

And so the Chinese took the path of least resistance. Anyone who has visited there in recent years knows the result: cities choked in coal haze, shiny new high-tension lines draping every ridge and valley in the same hypnotic swoop and fall as the Great Wall itself. And anyone who reads the rising carbon numbers from the instruments on the side of Mauna Loa knows the larger consequence: The world is now above even the bleakest “business as usual” paths laid out just a few years ago by climate policy experts.

But even for those — Europe and Japan — that wanted to do something about climate, the U.S. refusal to engage meant that nothing much could happen. Yes, the Kyoto treaty was finally ratified — somewhat miraculously, since without our participation it required virtually every other developed nation to sign on. But because of America’s recalcitrance (right back to the Clinton years) they were never strong enough to do much in any event. The eight Bush years turned into an international interregnum on climate policy. The American delegations sabotaged international meetings, slowed down any proposal to actually change, and in general served as the anchor thrown off the back of the caboose.

It’s not entirely clear that even the most well-intentioned president could have headed off the China coal binge. It would have taken a shrewd mix of diplomacy, technology-sharing, and moral pressure to head them in a different direction. But even subtle nudges in their trajectory in the early years of the decade would have resulted in far less damage than we see today. And, of course, we’ll never know since Bush didn’t try. If anything, his team cheered on the Chinese.

As a result of all this planned malfeasance, Bush leaves Obama in the worst possible place to do anything substantial about carbon. For one thing, the Chinese now have all those coal-fired power plants and so, just like us, an enormous problem with sunk costs if they ever try to shut them down. (And shut them down is what Jim Hansen has told us must happen; if the earth is not done burning coal by 2030, then 350 parts per million CO2 goes forever by the board.) And because the Chinese are now producing as much CO2 as we are, our own coal lobby has a powerful rhetorical argument to use against any real action close to home. You can hear it anytime you want on C-Span — some coal-state Republican or another announcing piously that it “will do no good for America to reign in its carbon emissions until China does the same.”

Negotiating away the results of these eight years will be Obama’s biggest environmental task, bigger even than figuring out how to limit our own emissions. By Copenhagen next December, the Americans and the Chinese will need to have rechoreographed entirely the poisonous dance they’ve spent the last decade perfecting. If they can’t, the possibility of a breakthrough agreement is nil.

Oh, and since the most important element of that breakthrough will doubtless be finding some way to partially compensate China (still an overwhelmingly poor nation) for the cost of switching to more expensive fuel sources, the recession that Bush leaves us with is yet one more obstacle. If he’d set out to purposefully screw up the chances for dealing with global warming, it’s unlikely Bush could have done a better job. (But the purposeful party was no doubt Dick Cheney.)