If the images of skyscrapers collapsed in heaps of ash were the end of one story — the U.S. safe on its isolated continent from the turmoil of the world — then the picture of the sodden Superdome with its peeling roof marks the beginning of the next story, the one that will dominate our politics in the coming decades: America befuddled about how to cope with a planet suddenly turned unstable and unpredictable.

Over and over last week, people said that the scenes from the convention center, the highway overpasses, and the other suddenly infamous Crescent City venues didn’t “look like America,” that they seemed instead to be straight from the Third World. That was almost literally accurate, for poor, black New Orleans (which had never previously been of any interest to the larger public) is not so different from other poor, black parts of the world: its infant mortality rates, life expectancy rates, and educational achievement statistics mirroring those of many African and Latin American enclaves.

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But it was accurate in another way, too, one full of portent for the future. A decade ago, environmental researcher Norman Myers began trying to add up the number of humans at risk of losing their homes from global warming. He looked at all the obvious places — coastal China, India, Bangladesh, the tiny island states of the Pacific and Indian oceans, the Nile delta, Mozambique, on and on — and predicted that by 2050 it was entirely possible that 150 million people could be “environmental refugees” [PDF], forced from their homes by rising waters. That’s more than the number of political refugees sent scurrying by the bloody century we’ve just endured.

Try to imagine, that is, the chaos that attends busing 15,000 people from one football stadium to another in the richest nation on earth, and then increase it by four orders of magnitude and re-situate it to the poorest nations on earth.

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And then try to imagine doing it over and over again — probably without the buses.

Because so far, even as blogs and websites all over the internet fill with accusations about the scandalous lack of planning that led to the collapse of the levees in New Orleans, almost no one is addressing the much larger problems: the scandalous lack of planning that has kept us from even beginning to address climate change, and the sad fact that global warming means the future will be full of just this kind of horror.

Consider the first problem for just a minute. No single hurricane is “the result” of global warming, but a month before Katrina hit, MIT hurricane specialist Kerry Emanuel published a landmark paper in the British science magazine Nature showing that tropical storms were now lasting half again as long and spinning winds 50 percent more powerful than just a few decades before. The only plausible cause: the ever-warmer tropical seas on which these storms thrive. Katrina, a Category 1 storm when it crossed Florida, roared to full life in the abnormally hot water of the Gulf of Mexico. It then punched its way into Louisiana and Mississippi — the latter a state now governed by Haley Barbour, who in an earlier incarnation as a GOP power broker and energy lobbyist helped persuade President Bush to renege on his promise to treat carbon dioxide as a pollutant.

So far the U.S. has done exactly nothing even to try to slow the progress of climate change: We’re emitting far more carbon than we were in 1988, when scientists issued their first prescient global-warming warnings. Even if, at that moment, we’d started doing all that we could to overhaul our energy economy, we’d probably still be stuck with the 1 degree Fahrenheit increase in global average temperature that’s already driving our current disruptions. Now scientists predict that without truly dramatic change in the very near future, we’re likely to see the planet’s mercury rise 5 degrees before this century is out. That is, five times more than we’ve seen so far.

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Which leads us to the second problem: For the 10,000 years of human civilization, we’ve relied on the planet’s basic physical stability. Sure, there have been hurricanes and droughts and volcanoes and tsunamis, but averaged out across the earth, it’s been a remarkably stable run. If your grandparents inhabited a particular island, chances were that you could too. If you could grow corn in your field, you could pretty much count on your grandkids being able to do likewise. Those are now suckers’ bets — that’s what those predictions about environmental refugees really mean.

Here’s another way of saying it: In the last century, we’ve seen change in human societies speed up to an almost unimaginable level, one that has stressed every part of our civilization. In this century, we’re going to see the natural world change at the same kind of rate. That’s what happens when you increase the amount of heat trapped in the atmosphere. That extra energy expresses itself in every way you can imagine: more wind, more evaporation, more rain, more melt, more … more … more.

And there is no reason to think we can cope. Take New Orleans as an example. It is currently pro forma for politicians to announce that the city will be rebuilt, and doubtless it will be. Once. But if hurricanes like Katrina go from once-in-a-century storms to once-in-a-decade-or-two storms, how many times will we rebuild it? Even in America there’s not that kind of money — especially if you’re also having to cope with, say, the effects on agriculture of more frequent and severe heat waves, and the effects on human health of the spread of mosquito-borne diseases like dengue fever and malaria, and so on ad infinitum. Not to mention the costs of converting our energy system to run on something less suicidal than fossil fuels, a task that becomes more expensive with every year that passes.

Our rulers have insisted by both word and deed that the laws of physics and chemistry do not apply to us. That delusion will now start to vanish. Katrina marks Year One of our new calendar, the start of an age in which the physical world has flipped from sure and secure to volatile and unhinged. New Orleans doesn’t look like the America we’ve lived in. But it very much resembles the planet we will inhabit for the rest of our lives.

This essay was originally published in TomDispatch.com.