While the Baker-Hamilton report from the Iraq Study Group dominates the news in recent weeks with its rebuke of the colossal mess the United States has made in Iraq, there is another report released at the end of October -- even more vital in its import -- that has gone virtually unnoticed. I'm referring to the Stern Review on the Economics of Climate Change, released by the U.K. government, which has received far too little attention in the U.S. press. It too is about a colossal mess we've made, not in a single nation but in the atmosphere of the entire planet, with possible consequences for all life on earth.

If the news in the Stern Review is scary to think about, it's ultimately a message of hope: It's not too late to act on global warming -- provided we take strong, united global action, starting now and increasing over the next 10 years. Indeed, "delay would be dangerous and much more costly," the Review warns. What's powerful about the report is that it positions the issue in easy-to-grasp economic terms. It estimates that acting now to stabilize climate change could cost 1 percent of global GDP each year -- which is relatively manageable -- but not acting could create losses that dwarf that. Likely the losses from inaction, the Review estimates, would reach 5 percent to 20 percent of global GDP year after year, "now and forever."

For politicians who argue that taking action now to reduce global warming emissions is too costly in economic terms, the Stern Review offers a stern rebuke: The real economic damage will come not from action but inaction. And as a measure of the report's economic credibility, it was commissioned by the British Chancellor of the Exchequer, was prepared by one of the world's leading economists, Sir Nicholas Stern, and has been endorsed by four Nobel Prize-winning economists plus the president of the World Bank.

The Stern Review offers powerful economic ammunition for the global warming debates that will play out in politics in coming months and years. But as useful as it is, it takes us only part of the way. An analysis by my colleagues at the Tellus Institute shows that the report stops short on two counts.

First, it looks only at environmental damages that can be monetized and quantified, when the risk of catastrophic changes in the climate and ecological systems are far more unknowable. "The Stern Review should be considered a conservative estimate of the dangers," says Tellus President Paul Raskin. By using only monetized values, he added, "it's like looking at a mountain through a pinhole."

Second -- and more consequential -- is the question of how we get to a world of reduced emissions. The Stern Review concludes that climate stabilization will require that annual greenhouse gas emissions be brought down more than 80 percent below current levels. And it predicts that this can be achieved without significantly compromising world economic growth -- since the shift to a low-carbon economy will create huge business opportunities in developing low-carbon and high-efficiency products. As the U.K. Treasury put it in a public statement,
"Tackling climate change is the pro-growth strategy."

While this optimistic assessment may in an economic sense prove true, it underplays the enormous lifestyle changes that will ultimately be necessary if massive global climate change is to be averted. "It's a question of both necessity and opportunity," Raskin says. The necessity is that we can't get to a sustainable world by any other pathway than that of deep and fundamental changes in how we live. The opportunity is that this could lead us "to a world of greater human fulfillment," he adds.

Imagine, for a moment, that each of us reduced our own personal energy use by 80 percent. Families might have one car rather than two, we might drive dramatically less often -- staying home rather than going to the mall, living closer to where we work -- and we might travel less frequently, in all instances leaving us more time for our families, potentially more connected to our neighbors. We might choose smaller houses that are far more energy-efficient, and we'd likely be buying local -- giving up our Italian sparkling water shipped halfway around the world. We might eat fruits and vegetables in season, reestablishing our relationship to the rhythm of the seasons.

We might, in short, have better, happier lives. We might have less stuff, yet closer relations with nature and our fellow human beings, and greater well-being as a result.

Climate change might, in the end, prove itself an optimal crisis. It could be among the catalytic forces -- along with reaching peak oil production and other forms of ecological exhaustion -- that are grave enough to break us out of our cultural trance, yet not so insurmountable as to crush our spirit. It might spur human society to the fundamental transformation that our culture so desperately needs, to move us from a culture of consumption and waste and isolation to one of sustainability and community and, yes I'll say it, happiness.

In his new book, "The Upside of Down: Catastrophe, Creativity, and the Renewal of Civilization," Thomas Homer-Dixon makes precisely this point. Many religious people think we're entering end times, he writes, and their intuition is largely right. "Some kind of real trouble does lie ahead. That trouble doesn't have to be calamitous in its ultimate results, though," he writes.

Homer-Dixon -- like many people today -- sees that some kind of societal breakdown is increasingly likely. But it can give rise to what he terms "catagenesis," a collapse or breakdown that leads to genesis, to the birth of "something new, unexpected, and potentially good."

Constrained breakdown can "shatter the forces standing in the way of change," he writes. "It can, in short, be a source of immense creativity -- a shock that opens up political, social, and psychological space for fresh ideas, actions, institutions, and technologies that weren't possible before."

The breakdown of the Iraq war has already proven such an event. We might view it culturally as the shock to the system that opened up a new political space, sweeping the Democrats into power. And the Democrats, even before they've taken office, have begun to propose action on global warming that goes beyond what any of us dreamed was politically possible just a few short months ago.

Future speaker of the House Nancy Pelosi -- along with 109 others -- has recently endorsed legislation, sponsored by Rep. Henry Waxman of California, that sets a target of reducing greenhouse gas emissions by 80 percent by 2050. Which corresponds to the Stern Review assessment.

Imagine that: One of the most powerful leaders in Congress endorsing 80 percent reductions in greenhouse gases. Somebody pinch me. On Oct. 30 -- when the Stern Review came out -- I would have told you such a goal would remain politically unmentionable for a decade or more. But all that changed two days later, when Nov. 2 elections unfolded.

Things can change dramatically, and they can change overnight, and that change can make our lives better. That's the hidden opportunity in global warming. In a word, hope.