For years, advocates of climate-change legislation have struggled to find a sales pitch that will sway even the most hardened of skeptics. Polar bears, green jobs, urgent pleas to think of the grandkids … none of them have quite done the trick. But recently, a new argument has come to the fore: the national security case for cutting carbon emissions. At a hearing in October, Senate Democrats invited military leaders and strategists to speak about both the dangers of America’s oil dependency and the potential for rising temperatures to create new security threats around the globe. Dennis McGinn, a retired Navy vice admiral, conjured up a not-too-distant future in which increased drought, flooding, and crop failures ravaged areas like sub-Saharan Africa or Bangladesh, fueling violent conflict. Meanwhile, he said, the U.S. military could find itself handcuffed by its over-reliance on oil if prices start spiking. “Continuing the United States’ pattern of energy usage in a business-as-usual manner,” McGinn warned, “creates an unacceptably high threat level.”

It’s a claim that resonates far and wide. In August, a poll by the American Security Project reported that most Americans agreed that global warming could “destabilize developing countries, creating the conditions for war and a breeding ground for terrorism.” A recent survey in Arkansas--hardly a hotbed of green sentiment--found that, when the security case was placed alongside the conservative mantra that capping carbon amounts to a giant tax, people favored cutting emissions 55 percent to 37 percent. The argument has even wooed conservatives who wouldn’t be caught dead at an Earth Day rally. Republican Lindsey Graham recently explained his interest in climate legislation by arguing that global warming could “make the world even a much more dangerous place. It’s not just me saying it. A bunch of generals are saying it.” The message is so effective that Democrats are counting on it to frame the climate debate: John Kerry, who has been working the security angle in private conversations with swing senators, was made lead sponsor of the Senate cap-and-trade bill for just this reason.

But even if climate-bill backers have finally found the potent argument they’ve been searching for, that still leaves the substantive issue: To what extent is global warming a national security concern for the United States? Right now, the Pentagon, the Armed Forces, and other security experts are trying to figure out just what dire consequences a warming planet might bring. And, as it turns out, the answers are more complex than the simple sales pitch might suggest.

The security argument comes in a variety of strains, but perhaps the one most commonly invoked has little to do with climate change per se--it involves oil. Military commanders in Iraq and Afghanistan, for instance, have become increasingly alarmed about their reliance on crude, not least because fuel convoys are ripe targets for attacks. “All the military departments are looking very specifically at how they take advantage of energy efficiency and lighten the burden of what our troops need to take to the front,” says Sherri Goodman, the former deputy under secretary of defense for environmental security during the Clinton administration. Then there’s the interrelated claim that America’s gas-guzzling ways help bankroll extremism in the Middle East. While this is a powerful reason to use less oil, it also only goes partway in making the case for tackling global warming--which, after all, requires an array of additional steps like zeroing out carbon emissions from coal plants and halting deforestation.

The more compelling climate-specific fear is the possibility that severe global-warming impacts could provoke conflicts around the world. In Sudan, there’s already evidence that warmer ocean temperatures have wreaked havoc on rainfall patterns, creating drought that pushed farmers in Darfur into competition for arable land with Arab pastoralists, with bloody results. That wasn’t the primary cause of the genocide there--the Khartoum government deserves the vast share of blame--but it’s an example of how ecological changes can tip tense situations over the brink. And climate science offers ample warning that similar disruptions could unfold across the globe. According to the Intergovernmental Panel on Climate Change, a global temperature rise of two degrees Celsius or more (which is precisely what climate campaigners are hoping to avert) would likely lead to more frequent droughts and crop failures across Africa, Asia, and Latin America; batter coastal regions with flooding and stronger storm surges; and aid the spread of infectious diseases. Glaciers in the Himalayas are expected to melt rapidly in the coming decades, shriveling up a key water source that Pakistan relies on for most of its crops, possibly setting the stage for conflict over rivers in Kashmir. And military experts have warned that greater resource scarcity could cause fragile governments to topple, pointing to events like the food shortages that helped lead to the fall of governments in Ethiopia and Niger in the 1970s. As a 2007 CNA report by a panel of retired military leaders describes, such failed states are ripe for terrorist havens and can succumb to the sort of anarchic violence that leads to calls for U.S. military intervention, as occurred in Somalia in the 1990s.

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These dystopian forecasts can sometimes get oversold--as they did in the ’90s, when Robert Kaplan’s influential Atlantic Monthly article, “The Coming Anarchy,” roiled Washington with its sensationalist vision of one African country after another disintegrating under the stress of dwindling water supplies and eroding cropland. In the years that followed Kaplan’s piece, many academics began poking holes in his thesis, pointing out that just as many, if not more, countries prove surprisingly resilient in the face of grave environmental stresses. And, as with Darfur, resources are only one risk factor; people themselves still have to decide to go to war. “You don’t want to frame it as a deterministic thing, that it’s all going to hell in a hand-basket,” says Geoff Dabelko, who directs the Environmental Change and Security Program at the Wilson Center. Still, Dabelko says, it’s understandable why the Pentagon is uneasy. “Look at Bangladesh. If sea levels rise and forty percent of the country is lost to inundation, where do those millions go? They’re going to India. Now we can say that’s not our problem, but there are two nuclear-armed states in the region. So, from the military’s perspective of risk analysis, if there’s a prospect of trouble, they’ve got to pay attention.”

Of course, whether many of these constitute a direct threat to U.S. security interests all depends on one’s view of what, exactly, U.S. security interests are--and what one thinks the military’s role in the world should be. At the moment, Pentagon planners are operating on the assumption that the military, whether it likes it or not, will be called on frequently to assist in a wide variety of climate-related crises, even ones that are primarily humanitarian in nature--as was the case in 2004 after a tsunami struck Indonesia. Yet not all experts think the implications of global warming should be defined so narrowly. “When you start talking about environmental issues this way, it brings the idea that you’re talking primarily about military solutions,” says Daniel Deudney, a political scientist at Johns Hopkins. “And, when we’re talking about climate, that’s not really where the most important actions are.”

It’s also possible that, in a few places, the security implications of climate change have been exaggerated. It’s not uncommon to see news stories hyping the notion that melting Arctic ice could create a mad scramble between the United States, Russia, Norway, and Canada for minerals and shipping lanes. Yet, as a Carnegie study of the subject found, “Overblown press coverage of Arctic security issues appears to be in inverse relationship to security realities. There are no large geopolitical fault lines, and no resource wars are anticipated.”

Likewise, for years, politicians have cautioned that ebbing water supplies could lead to an outbreak of “water wars.” But, experts point out, states have rarely gone to war over water--it’s much more common for them to cooperate and figure out ways to share resources, as with the Nile Basin Initiative in Africa. Peter Gleick of the Pacific Institute points out that the bigger concern should be violence within nations over water, which erupts quite frequently--in Ethiopia, between herdsmen, or in China, between local farmers wielding bombs. “More attention has been paid to those international disputes, because everyone’s worried about war,” says Gleick. “Yet those sub-national conflicts are much harder to address--and fewer resources have gone toward them.”

So framing climate change strictly as a national security problem for the United States may be an overly cramped way to think about the issue--even if it sells politically. Unchecked global warming will likely produce a lot of human misery around the world, but not all of that misery will create military threats. Then again, as retired General Gordon Sullivan wrote in the CNA report, there are also too many plausible high-risk scenarios to dismiss entirely. “We never have 100 percent certainty,” he observed. “If you wait until you have 100 percent certainty, something bad is going to happen on the battlefield.” In other words, we’d be nuts to sit back, let carbon emissions keep rising, and hope it all turns out okay.

Bradford Plumer is an assistant editor of The New Republic.

Not many Ph.D. students expect their research to generate outrage among Washington pundits decades later, but, as it turns out, that's exactly what happened to Stephen Schneider. Back in 1971, Schneider was studying plasma physics at Columbia and moonlighting as a research assistant at NASA's Goddard Institute for Space Studies. There, he co-authored an article for Science arguing that the warming effect caused by rising amounts of carbon-dioxide in the atmosphere would be swamped by the cooling effect caused by aerosol pollution like dust and smoke.

As it turned out, Schneider and his colleagues had made a calculation error--they neglected to account for the fact that aerosols were regional while CO2 was global--and their prediction of global cooling was later shown to be mistaken. Normally, that mistake would be unremarkable--a textbook example of how science advances and corrects its errors. Yet the paper is still, to this day, fodder for conservatives like George Will, who often bring up Schneider's earlier predictions as a reason why we shouldn't believe today's scientific consensus that the Earth is warming.

Nowadays, Schneider is one of the world's most prominent climatologists--in addition to his work as Professor of Biological Sciences and Interdisciplinary Environmental Studies at Stanford, he has been heavily involved in the Intergovernmental Panel on Climate Change (IPCC), a scientific body tasked with assessing the climate risks facing the planet. (Its most recent report, in 2007, concluded that most of the twentieth-century increase in global average temperatures was "very likely" due to human activities, and that world temperatures could rise between 1.1 and 6.4°C during the twenty-first century.) Notably, Schneider is also something of a scientific pugilist, known for his willingness to debate climate deniers and agitate publicly for sharp reductions in global greenhouse-gas emissions.

Schneider, whose new book, Science As A Contact Sport, just came out, sat down with The New Republic recently to talk about the current state of climate science, the difficulties in assessing risk, and how he balances his activist and scientific personas.

Given your early mistake about global cooling, why should we believe that scientists are better now at figuring out climate change?

There’s always the possibility of error. There’s always the possibility you left something out. But what we now have is an accumulated preponderance of evidence and that’s why the confidence is so much higher now than it was then.

And also continued uncertainty.

There is always uncertainty as well, but as scientists we’re always trying to move the needle toward more confidence. More confidence does not mean 100 percent confidence. The only thing the IPCC ever said it was 100 percent confident in was that it has been warming over the last 150 years. Some try to frame climate change by saying that as long as there remain open elements, it isn’t "proved." That’s a fraudulent frame. Nobody in this world--in medicine, investment banking, military security, environment--is ever 100 percent sure of anything in a complex system.

When I’m asked, "What is the probability that the Greenland ice sheet will melt if temperatures rise X degrees?," I speak in percentages. My very good friend and colleague Jim Hansen says, "One degree." I don’t think Jim knows that. I don’t think I know that. The problem is too complicated for us to know that, so I frame it as a risk management problem: One degree? 25 percent chance. Two degrees? 60 percent chance. Three degrees? 90 percent chance. Is that the truth? Of course not. That’s as honest as I can be based on my subjective reading of the evidence. However, just so you don’t think I’m an optimist relative to Jim, I also think there’s a 5 percent chance that it’s already too late.

What are some of the ways the IPCC’s risk assessment changed between 1990, when the First Assessment Report was published, and now?

As lead author on the climate science for 1995’s Second Assessment Report, I said that we needed to start quantifying what we meant by various kinds of uncertainty. What do we mean by "likely." What do we mean by "high confidence"? Well, my colleagues almost bit my head off! "You can’t do that! It’s not real science. Real science is empirical. Real science is modeling." I said, "We’re not doing science, guys. We’re doing science assessment." Most scientists are toilet-trained to do science. That’s okay, but that’s not IPCC’s job. IPCC was not asked by governments to do new science. It was asked to assess the existing literature base for quality and credibility, because there were so many false claims. The coal industry was saying, "Nobody knows anything." Greenpeace was saying, "The evidence is already too much." Scientists were saying, "We don’t know everything, so let’s not say anything." And the governments were saying, "We have to have some idea what the risk is."

You cannot address the problem of what to do, which is risk management, without addressing the problem of risk, which is probability times consequence. The fact that the event is in the future and the probability is subjective does not stop it from being expert. It’s still the judgment of people who understand as much or more than anyone in the world about how that system works. For the Third Assessment Report [in 2001], we were able to get an independent group to write a guidance paper on uncertainty. This was important to me because I knew that if we did not tell governments how likely climate change is, they would not listen to us about doing something about it.

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You talk about subjectivity, but isn’t science supposed to be objective?

No. Science is truthful, which doesn’t necessarily mean objective. How can science be objective about the future? How much data do we have for 2100? Try zero. We have data for 2009 and previous years. We take that data, analyze where we think it’s high quality, analyze where we’re not so sure of the quality, show how well the data explains multiple phenomena from the past, and ask how closely related those phenomena are to the future.

Then we build a model. It could just be a set of rules between how many watts of energy per square meter of heating we get between winter and summer and how much the temperature differs between winter and summer. That’s a model. Then we use it to predict how many watts per square meter from a doubling of CO2 in the atmosphere. Now, this model is not very good. We know enough to know it’s not very good. But that’s how you start thinking.

We then codify our knowledge in terms of the equations that best describe our understanding of each subsystem--atmosphere, oceans, chemistry, ecosystems, demography, economics, technology, etc. Every time we add a model, we add more uncertainty. This is called ‘theory,’ and everybody does theory, even data people. Then we create a super model, what we call an integrated system. None of the factors is known perfectly. But if we plot it as a bell curve we can bracket the answers. That’s why the IPCC says, "One to five degrees warming [by 2100]" for example. That is an expert judgment; it’s subjective, but built on objective modeling and data.

Our job is to examine our knowledge of the system and then make a diagnosis based on the way our models have predicted past events. If the models have done really well, we have more confidence. If they’ve done badly, we have low confidence. The models have done really well on temperature over a long time period so we trust that. They’ve done really badly on precipitation in the short run. We don’t trust that. So, we order the relative degree of credibility--not just in the model itself but in what the particular model predicts.

Therefore, the IPCC can say with very high confidence that we’re going to warm up a lot, and that warming will create fires and rising sea levels. Yet it has very low confidence in which year the fires will start to take off, where they will happen, and how severe they will be. But those are not inconsistent. 

Once we build our climate models, we must always make a subjective judgment, because it is going to be a prediction outside the realm of direct verifiability. We have to be able to predict whether this is a potential catastrophe for humanity. We can’t just hang around and wait.

In your book, you suggest a kind of continuum: from objective data to subjective determinations based on the data, and then to value judgments.

Right. What to do about what we know--that’s a question of values. But it’s values informed by science. In 1973, I got a call from the Council on Foreign Relations wanting me to talk about policy. I told them that if we’re using the atmosphere as a free sewer to dump our tailpipe wastes, and it’s going to cause change that could harm agriculture, ecosystems, ice sheets, and sea level, then maybe a smart move would be to slow down the rate at which we pollute. That’s a value judgment, and I’ve been making them from the beginning. I’m a very risk-averse person and I worry much more about the planetary life support system than the bottom line of the coal industry.

How then do you defend against charges that you’re an activist?

I am an activist. I want the world to be a better place, and I define specifically what I mean by that: If one group, the rich, benefits from an activity like dumping their waste in the atmosphere and the other group, the poor, are hurt by it and don’t get much benefit, that’s an inequity. Therefore, in my value system, that’s a higher criteria for action than aggregate dollars. I don’t have aggregate dollars as my moral principle. I look at who’s responsible. But I never say that without admitting that those are my values. So, that’s activism.

What’s the difference between being a climate-change skeptic and a denier?

Every good scientist is a skeptic. In fact, I would argue that every good citizen is a skeptic. We have to learn to discern, and listen to the quality and logic of an argument.

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For example, we don't understand to this day why smoking causes cancer, so we still retain an element of skepticism. But the data associating smokers with cancer is so statistically overwhelming that you would have to be a fool or a liar to deny it. It’s exactly the same in climate science. There’s an overwhelming preponderance of evidence that it’s warming, that the last thirty to forty years have been mostly due to human activities, that it’s raining more in higher latitudes, that there are more droughts and flooding, that ice is melting rapidly.

Then there is what’s going to happen to precipitation in Kansas. We don’t know. So the deniers come along and say, "We don’t know the precipitation in Kansas. These models are no damn good. It isn’t proved." That’s like saying "There are thirty-five tobacco studies; thirty-three of them show a dramatic statistical significance between smoking and cancer; two of them are equivocal. But until those two are resolved, it isn’t proved. Let’s not regulate cigarettes."

What else is in the climate denier’s toolkit?

“Theory not fact” is a favorite polemic. “Models not data” is another. There’s also “chartology,” where endpoints are cherry-picked to fit particular purposes. They pick the highest value of temperature many years ago and the lowest value now and draw a line through it and say there’s no warming trend. You can cherry-pick endpoints to exaggerate in either direction. That’s not how good science operates.

Another one is, "We have more scientists than you." In 1998, a group [Oregon Institute of Science and Medicine] sent out blanket emails to members of scientific societies--including medical societies, meteorology societies, etc.--and attached a petition saying, "We don’t believe in global warming." Seventeen thousand people signed it. The IPCC had only maybe two thousand people associated with it. So they said, "Many more scientists don’t believe it." But those who signed the petition are not [climate] experts and their opinion doesn’t matter.

Do you like the role you’ve come to play as the scientific pugilist?

I hate it. But my capacity to put down dishonesty is very good. I would rather that people have an honest and open debate--as in, "Excuse me, but I don’t really understand how you think this is unique and human-induced when it’s been warmer before." That’s a legitimate question. But the deniers do not like to argue with me and almost never do when I’m there.

In your book you note that you’ve sometimes been disgusted at how national interests trump planetary interests, but you also think we can overcome political inertia. How?

You overcome political inertia the way we’ve overcome it. California now has a climate policy, for example. You move very slowly. We’ve been talking climate policy in a serious way since 1988. We’ve got California. Now we have Waxman-Markey [the climate bill that passed the House this past June]. Sure, it’s going to be weak. It’s not enough, but it’s a move away from the wrong direction.

Oklahoma Republican James Inhofe, the most prominent global-warming denier in the Senate, has threatened to crash the upcoming climate negotiations in Copenhagen to make it clear to international leaders, he says, that the United States will never pass climate-change legislation.

Good. Let him. You think he isn’t going to be booed off the podium? They’ll hoot him down! I love to call him the Prevaricator Pro Tem.

What do you want to see happen at Copenhagen?

I want us to acknowledge that we need international cooperation; that poor countries have a right to develop but cannot expect to use traditional technologies to do it or we will pollute ourselves to death; and that rich countries, which created most of the initial problem, have an obligation to help those countries leapfrog over the industrial revolution to high technology.

I don’t care how much we cut by 2020 in terms of percentage points below 2005, which my environmental friends have focused on as the most important thing. Instead of getting hung up on what percentage we’re going to reduce, why don’t we talk about how many tens of billions of dollars each country is going to spend every year on helping ourselves out of the problem, and what cooperative strategies we can enter into with China, India, Indonesia, Brazil, and Mexico? Between our companies and their companies, we would share profits and patents.

I want policies and measures, not targets without teeth. I argued this in Kyoto and got shouted down. I wanted an international carbon tax, with revenue recycled to poor countries and directed toward inventions to get us out of the problem. Oh man, everybody hated that!

Will those of us arguing for such policies and measures succeed? I think partly. We will have weaker targets than any of us would like to see. We will have weaker policies than we’d like to see, but much stronger than we’ve ever seen before.

Marilyn Berlin Snell is a San Francisco-based journalist.

Nukes, nukes, and … nukes. These days, when it comes to energy and climate change, that seems to be all Republicans want to talk about. Throughout last week's hearings on the Senate climate bill, Lamar Alexander kept interjecting that a massive ramp-up of nuclear power was the only real solution to global warming, bringing up the subject at every turn. For many of his colleagues, it's one of the few energy ideas that piques any interest at all. "Certainly, nuclear production, advancing that would be important to my side of the aisle--regardless of what bill you are talking about," Bob Corker declared.

That view is not wholly without merit. Many projections for a low-carbon future do envision a supporting role for nuclear power--indeed, a cap-and-trade system for greenhouse gases, by making fossil fuels pricier, could help usher in the first new wave of reactors in the United States since the 1970s. But that's not enough for the GOP, which wants to put nuclear into overdrive. The party's energy plan, released in July, calls for a whopping 100 new reactors built by 2030. That's twice as many as even the most optimistic industry forecasts envision, and, given that the plants are estimated to cost at least $6-$10 billion a pop and have difficulty attracting private investment, they would likely need hefty subsidies--something the right is supposed to frown at. "For reasons I don't fully understand," says Joe Romm of the Center for American Progress, "nuclear power has a magical place in the hearts of conservatives."

The debate over nukes has long exacerbated the deadlock over climate policy. Of the handful of Republicans who think global warming is a serious problem--like Alexander--most refuse to address it unless nuclear power gets a starring role. But many Democrats and green groups are loath to lavish even more money on an industry that has received countless subsidies to date--including $18.5 billion in federal loan guarantees in 2005--yet still struggles to procure financing for new plants, to say nothing of concerns about safety and waste disposal. John McCain has chalked up his refusal to support the very cap-and-trade policies he once championed to "left-wing environmentalist organizations that are not allowing us to move forward with nuclear power."

Now, however, that deadlock may be dissolving. In October, John Kerry, the lead sponsor of the Senate cap-and-trade bill, co-authored a New York Times op-ed with Republican Lindsey Graham outlining a possible bipartisan deal that would include offshore drilling and nukes. "Nuclear power needs to be a core component of electricity generation if we are to meet our emission reduction targets," they wrote, endorsing the need to "jettison cumbersome regulations" and help utilities "secure financing for more plants." Graham has hinted that sufficient nuclear incentives could get "at least half a dozen" Republicans on board--allowing a climate bill to squeak through the Senate. As a result, many liberals and environmental groups are gritting their teeth and nervously bracing for a possible compromise. But that raises the question: If Democrats do haggle on nukes, will Republicans actually step up and agree to tackle global warming?

Tracing the GOP's love affair with the atom isn't easy. For much of the postwar era, nuclear power had broad bipartisan support in Congress. It wasn't until the early 1970s, when environmental and consumer groups began fretting about issues like reactor safety, that divisions emerged. "Democrats started advocating a slower approach, with tougher regulations, rather than the all-engines approach that had been the norm," says Robert Duffy, author of Nuclear Politics in America. In the 1980s, as one nuclear project after another stalled in the face of cost overruns, conservatives blamed excessive regulations and green meddling for the industry's woes. Even as Ronald Reagan's Nuclear Regulatory Commission was revising rules to make it easier for utilities to build plants, says Duffy, "there was always this perspective that government was to blame."

The battle lines of this earlier clash are still visible today. McCain, for one, "feels instinctively that nuclear has been dealt an unfair hand," as one of his campaign advisers told me last year. Alexander was governor of Tennessee in the 1980s when the Tennessee Valley Authority, much to his chagrin, mothballed three planned reactors due to soaring costs. Local politics matter, too: Graham's state of South Carolina is home to seven reactors, and his political campaigns have relied on generous support from nuclear utilities. Plus, of course, hyping a low-carbon energy source lets conservatives scoff at environmentalists for not being "serious" about global warming.

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Whatever the reason, the issue has often thrown a wrench in climate politics. When McCain brought his cap-and-trade bill up for a vote in 2005, he added a slew of nuclear subsidies--and lost four liberal Democrats who had voted for his 2003 version, including Barbara Boxer, Tom Harkin, and Russ Feingold. When, in 2007, Joe Lieberman and Virginia Republican John Warner put forward their own cap-and-trade bill, they shied away from nuclear altogether--and lost McCain. "We wanted to discuss it, but we were hamstrung by what we could get through working with Boxer," recalls Chelsea Maxwell, a former Warner aide.

Now that a climate bill has a realistic shot at passing, however, liberals may be softening their stance. In October, President Obama told a town-hall crowd in New Orleans, "There's no reason why, technologically, we can't employ nuclear power in a safe and effective way." (Alex Flint, a lobbyist for the Nuclear Energy Institute, or NEI, pointed to Obama's remarks as a sign that the tide was turning.) Boxer, who is co-sponsoring the Senate climate bill, may not be thrilled with the idea of more goodies for the nuclear industry, but she did allow Tom Carper, a pro-nuke Democrat, to draft a few small provisions on things like training new nuclear engineers. Even Harkin, a staunch nuclear critic, is staying cautious: While he thinks the industry gets enough support as is, Senate sources say he's still in wait-and-see mode. "Right now, everyone's staying open-minded," says one staffer working on the issue.

Granted, much depends on what nuclear backers actually ask for. NEI recently circulated a wish-list to Congress calling for new tax breaks and a green bank that would dole out $100 billion in loan guarantees for clean-tech projects, including nuclear. Critics fear a disproportionate focus on nukes would crowd out more cost-effective energy projects and tie up money in plants that can take a decade to build and have a high risk of default. (A 2009 Moody's report called new reactors a "‘bet the farm' endeavor for most companies" and said that federal support would only "modestly" mitigate this risk.) More contentious still, NEI and its allies have stressed the need to "streamline" the licensing process and reduce the delays that have plagued the industry and scared off investors.

At the moment, few environmental groups will publicly say what their red lines on nuclear are, but, privately, some suggest that any moves to weaken safety oversight or restrict public participation over the siting of new plants could repel even moderate greens. "There are a lot of very technical issues at stake here, and we don't think Congress should be tying the Nuclear Regulatory Commission's hands," says Ed Lyman of the Union of Concerned Scientists, a nuclear watchdog organization.

Plus, there's little point in acceding to the GOP's nuclear demands without getting anything in return. Alexander, for one, recently admitted that, even though he's taking part in talks over new nuclear provisions, nothing will persuade him to support a cap on carbon--which is the crux of any climate bill. "That's something to watch out for," grumbles one observer. "Is NEI actually going to work to bring new votes to the table?" Perhaps it's finally time to see just how much this love affair is worth.

Bradford Plumer is an assistant editor of The New Republic.

In 2001, an entrepreneur named Tom Casten traveled down to southern Louisiana, near the small town of Franklin, with a clever idea. For decades, the area had sustained a pair of chemical plants that produced carbon black, a grimy powder used in printer ink and tire rubber. But the owner of one of the plants, Cabot Corporation, was struggling to compete against cheap tire imports from abroad, and desperately seeking ways to cut costs. That’s where Casten came in. He pointed out that the gas left over from the carbon-black process was just getting wasted--burned off and flared up into the sky. He proposed building a recycling facility that could capture the gas and use it to generate electricity. Not only would this make the plant slightly cleaner--carbon-black plants are notorious polluters--but there’d be enough juice to run Cabot’s operations, and for less than it cost to buy power from the local utility. In all, the company could save up to $1.3 million per year.

It's been a long year--Barack Obama has faced, in rough order, John McCain, global financial collapse, Mahmoud Ahmadinejad, the Blue Dogs, the Progressive Caucus, the Gang of Six, Glenn Beck, Representative Joe Wilson (R-Hissy), and the third of Republicans convinced he was born somewhere else. Of course, minus the birth certificates, roughly the same has been true for Hu Jintao and Nicolas Sarkozy, for Angela Merkel and Manmohan Singh. That's what politics is--a series of challenges, which are rarely won or lost completely. You get part of what you wanted (everyone with health insurance), and maybe you leave other stuff for another day (the public option). That's why we call politics the pursuit of the possible.

Our oceans have been the victims of a giant Ponzi scheme, waged with Bernie Madoff–like callousness by the world’s fisheries. Beginning in the 1950s, as their operations became increasingly industrialized--with onboard refrigeration, acoustic fish-finders, and, later, GPS--they first depleted stocks of cod, hake, flounder, sole, and halibut in the Northern Hemisphere. As those stocks disappeared, the fleets moved southward, to the coasts of developing nations and, ultimately, all the way to the shores of Antarctica, searching for icefishes and rockcods, and, more recently, for small, shrimplike krill. As the bounty of coastal waters dropped, fisheries moved further offshore, to deeper waters. And, finally, as the larger fish began to disappear, boats began to catch fish that were smaller and uglier--fish never before considered fit for human consumption. Many were renamed so that they could be marketed: The suspicious slimehead became the delicious orange roughy, while the worrisome Patagonian toothfish became the wholesome Chilean seabass. Others, like the homely hoki, were cut up so they could be sold sight-unseen as fish sticks and filets in fast-food restaurants and the frozen-food aisle.

This Saturday afternoon, at the Values Voter Summit in Washington, the time for ideological issue training had arrived, and a breakout session on climate change was packed. An organizer in a long black skirt swept through and instructed people to move their chairs to the side, like her father’s Baptist congregation would do when space got tight.

"It’s already warmer in here, all the CO2 in the room," chuckled a tall, suited attendee.

"This is a hot topic!" cracked another.

In the winter of 1984, a young scientist named Steven Chu was working as the new head of the quantum electronics division at AT&T's Bell Labs in Holmdel, New Jersey. For months, he'd been struggling to find ways to trap atoms with light so that he could hold them in place and study them better. It was an idea he'd picked up from an older colleague, Arthur Ashkin, who had wrangled with the problem all through the 1970s before finally being told to shut the project down--which he did, until Chu came along. ("I was this new, young person who he could corrupt," Chu later joked.) Now Chu, too, had hit an impasse until, one night, a fierce snowstorm swirled through New Jersey. Everyone at Bell had left early except for Chu, who lived nearby and decided to stay a bit longer. As he watched the snow drift outside, he realized they'd been approaching the problem incorrectly: He first needed to cool the atoms, so that they were moving only as fast as ants, rather than fighter jets; only then could he predict their movements and trap them with lasers. It was a key insight, and Chu's subsequent work on cooling atoms eventually earned him a share of the Nobel Prize in physics.

While it may sound inevitable in retrospect, big breakthroughs like that don't come along too often. Nowadays, though, Chu is betting that they will-- and must. As the U.S. energy secretary, Chu has been tasked with reshaping the country's trillion-dollar energy economy, to reduce America's reliance on fossil fuels and cut greenhouse-gas emissions 80 percent or more by mid-century- -essential to avoiding catastrophic climate change. It's an enormous goal, and Chu believes the only way to achieve it is with multiple Nobel-caliber leaps in energy technology. "I mean technology that is game-changing, as opposed to merely incremental," he told Congress in March--technology that, as a recent Department of Energy (DOE) task force described it, will require an understanding of basic physics and chemistry "beyond our present reach."

Not everyone agrees that the fate of the planet hinges on such far-reaching advances. Given the increasingly dire revelations of climate science-- greenhouse-gas emissions are rising more quickly than projected, Arctic sea ice is melting faster than once thought possible--many analysts believe we need to act with all due haste, before the planet hits a tipping point. And much of the green movement tends to follow Al Gore's oft-stated assurance that, "to save the future, we have everything we need except the political will." Chu's view also sits uneasily alongside that of the U.N. Intergovernmental Panel on Climate Change (ipcc), which, in 2007, declared that stabilizing carbon in the atmosphere below safe levels could be done with a mix of technologies that were either currently available (like wind power) or just around the bend (plug-in hybrids, for instance). This camp argues that, while existing clean-energy gadgets may have flaws, they'll get steadily better and cheaper as they're deployed, and, in any case, the immense urgency of the climate problem leaves us little alternative.

Chu, for his part, acknowledges that the threat posed by global warming requires a wide array of practical and immediate responses, including a cap on carbon emissions to make fossil fuels less competitive. Still, according to those familiar with his thinking, Chu sees the challenge of spurring breakthroughs in energy research as an even larger priority than setting a carbon price and promoting existing clean-energy sources. "I think science and technology can generate much better choices," he told The New York Times in February. "It has, consistently, over hundreds and hundreds of years."

It's an attractive vision. There's no question, after all, that investments in energy R&D have become dangerously anemic over the years, and that better technology would make the task of curbing emissions far less arduous. But Chu's stance raises plenty of knotty questions. What's the best way to promote innovation? And can these vast leaps in scientific understanding arrive in time to fend off rising global temperatures? And, most importantly, what happens if they don't? As it turns out, there's reason to worry that counting on radical breakthroughs to save the planet may be a fraught and uncertain venture.

Talk to chemists and physicists toiling on the frontiers of clean energy research and it's easy to be dazzled by the possibilities. Take solar power. The sun radiates more energy down to Earth in an hour than humans use in a year. It's just that, right now, even the best solar photovoltaic panels are relatively inefficient at harvesting that resource--and storing the energy for when the sun isn't shining remains tricky. So, some scientists have gone back to the drawing board and tried to pursue artificial photosynthesis, mimicking the deft process that plants use to turn sunlight and water into fuel.

Progress has been slow, but, in 2008, Daniel Nocera, a chemist at MIT, made headlines for a breakthrough in one small piece of this project. He created a cheap chemical catalyst that could use solar energy to break down water into oxygen and hydrogen, which could then be stored or run through a fuel cell to generate electricity. "In theory, if you could use the sun's energy to convert just one-third of the amount of water in an Olympic-sized swimming pool into hydrogen and oxygen per second, you could take care of the world's energy needs, " Nocera explains. At the time it was announced, one researcher called it "probably the most important single discovery of the century" for solar power, and the news conjured up shiny visions of leaf-like catalysts creating hydrogen fuel to power homes and cars--provided, of course, that a flurry of follow-up problems could be resolved: how to absorb sunlight more efficiently, how to build the fuel cells, how to store the hydrogen cheaply, and so on. Those hurdles are formidable, and Nocera has his fair share of doubters, but the broad concept is undeniably appealing.

Over the past few years, the DOE's Office of Basic Energy Sciences has released a series of reports that have taken such "if only..." notions quite seriously. The premise of these reports is that existing clean-energy technologies--from batteries to nuclear power--have hit ceilings that can't be surpassed by engineering alone or by the tinkering that private companies are now doing at the margins. In many cases, cracking these limits will require dramatic strides in scientific understanding. "Companies are doing great work, but it's all been based on an existing set of basic concepts and understandings to which we need to continue to add," says Mark Ratner, a chemist at Northwestern University who contributed to the DOE reports.

These next-level breakthroughs may, in effect, require a whole new type of science. Ratner explains that, during the twentieth century, scientists became increasingly sophisticated at studying quantum effects and examining matter at an ever-smaller scale--leading to the discovery of key materials such as superconductors and carbon nanotubes. Now, he says, the big challenge is to step beyond observation and figure out how to actually control and direct matter and energy at the atomic level. "We still don't really know how to control chemical reactions at that level, for instance," he says. "Something like that could really deepen what we could do."

Last December, the office released an "energy challenges" report that offered a lavish vision of what a new "control science" could accomplish. If, for instance, the steel used to make nuclear reactors was built by manipulating atoms at the nanoscale, rather than through traditional bulk processes, we could have materials that self-heal and better resist chemical corrosion and intense radiation, allowing the construction of nuclear reactors that operate at much higher temperatures and efficiencies--meaning more power and less waste. Or ultra-light materials could be used to build cars that require far less energy to propel. Or batteries built on chemistry yet unknown could allow electric vehicles to vastly surpass their currently limited range. Or solid- state lighting that used just a fraction of the power that incandescent light bulbs use, and without the glare of compact fluorescent lights, could drop the percentage of electricity the nation needs for lighting from 22 to 2 percent.

While the DOE reports were drafted during the Bush years--conservatives have often touted technological upheaval as the solution to climate change, but mainly as an excuse to put off carbon regulations--the findings have particularly resonated with Chu, who has long agreed that deep research and disruptive new technologies are necessary for solving our energy woes. With funds pouring in from the Obama administration, the DOE's labs are beginning to channel their basic research efforts toward specific energy problems, both big and small. "There's always a question of how much you focus on engineering and how much on targeted, basic research," says George Crabtree, a scientist at Argonne National Laboratory who helped oversee the DOE reports. "It's dangerous to say this, because I love engineering-- the plug-in hybrid, that was engineering. But we need to shift back a bit to the basic sciences side."

As alluring as this scientific vision may be, we may not have time to wait for radical advances to emerge. Global warming is happening now, and many of the changes needed to slow or stop it will have to be made in the next few decades. According to the ipcc, wealthy countries need to cut their carbon- dioxide emissions by up to 40 percent below 1990 levels by 2020, and by more than 80 percent by 2050, in order to have a shot at stabilizing atmospheric carbon levels below 450 parts per million. Skate past that number and we run a high risk of triggering carbon-cycle feedbacks beyond our control, putting the world on course for massive sea-level rises, widespread drought, and other assorted horrors.

"We need to replace the entire energy system in three or four decades," says Joseph Romm, a Clinton-era Energy Department official and one of the fiercest critics of those banking on major technological breakthroughs. "The notion that technology that doesn't even exist yet could be invented, demonstrated, and then commercialized in that time frame--it's absurd."

Indeed, the question of timing turns out to be utterly central. Chu is mindful of this: In addition to his longer-term vision, he has put an emphasis on intermediate advances that can scale up in just five to ten years with proper support--from improved batteries to sensor-based technology to cut energy use in buildings. Yet many of the truly sweeping breakthroughs envisioned by the DOE task force could take far longer, and the energy industry tends to evolve at a sluggish pace, with major new discoveries often taking decades to filter into the marketplace.

Consider, for instance, the high-temperature superconductor. In 1986, two researchers at IBM's labs in Zurich, Alex Muller and Georg Bednorz, announced that they had discovered a new brittle ceramic compound that could conduct electricity with little resistance at relatively high temperatures (previous superconductors needed to be cooled with expensive liquid helium, making them impractical for most uses except boutique applications, such as MRIs and particle accelerators). Condensed-matter physicists everywhere swooned over the news. The press giddied itself over a "Jetsons"-esque future replete with magnetically levitated trains, ultrafast computers, and new transmission lines that could carry five times as much electricity as normal lines over long distances with low losses--a true game-changer for electricity markets. "That summer, I made a lot of money as a consultant," chuckles Bruce Strauss, a high- energy physicist who now works for DOE. "You saw venture capitalists running around with open checkbooks, asking, 'Where should I invest?' I kept telling them you're not going to see real applications for twenty or thirty years--they looked at me like I was a doomsayer." Sure enough, more than 20 years later, those transmission lines are still in the embryonic stage. The superconductors perform admirably in demonstration projects, but no one has mastered a way to bring production costs down to halfway reasonable levels.

While counterexamples exist, some analysts warn that the superconductor case is all too illustrative. Romm cites a 2001 study by Royal Dutch/Shell Group, which found that, historically, "it has taken 25 years after commercial introduction for a primary energy form to obtain a 1 percent share of the global market." Silicon solar photovoltaic cells, for instance, ranked as a major advance when they were developed more than half a century ago, yet they still provide less than 0.1 percent of America's electricity today. How much longer might it take for even more complex inventions--artificial photosynthesis, say--to journey from the laboratory out into widespread use? (Even Chu recognizes that some inventions may not emerge in a reasonable time frame: He recently cut federal support for hydrogen-powered cars, arguing that widely deploying these vehicles in the next few decades would require "four significant technological breakthroughs"--too improbable for even the most fervent believers in science.)

There may be an even more basic problem, too: Science has to continue rapidly advancing--or even speed up--for many of these big breakthroughs to occur in the first place. Last year's DOE report argued that achieving its futuristic vision would require significantly increasing the rate of scientific discovery, in part because, as the materials and phenomena under study get more complex, entirely new scientific laws often need to be grasped at each step of the way. "Look at superconductivity," explains Graham Fleming, a chemist at the University of California, Berkeley who contributed to the DOE reports. "It's got what's called an emergent property--just knowing the properties of the parts doesn't help a lot. Having a better theoretical understanding of those emergent systems is something we need. Right now there's an awful lot of trial and error in making materials that are much more efficient and effective."

So what are the odds that the pace of scientific discovery can accelerate? This is a hotly debated topic, with a wide spectrum of answers. In 2005, Jonathan Huebner, a physicist working at Pentagon's Naval Air Warfare Center in China Lake, California, published a controversial paper looking at the rate of U.S. patents awarded over time. He argued that the rate of technological innovation has actually been slowing since around 1873--the age of Edison--and that the world could be entering a new Dark Age of innovation by the 2020s. Huebner's paper came under heavy fire from a number of innovation scholars, including Ray Kurzweil, a futurist who is inordinately bullish on the rate of technological progress and who, to his credit, has made a number of bang-on forecasts. (He famously predicted that a computer would be able to beat a grandmaster in chess by the late 1990s.) Kurzweil has suggested that technological change will continue zooming forward until artificial- intelligence machines start replicating themselves. At that point--in or around 2045--the pace of innovation will happen so blindingly fast as to be inconceivable. Presumably the answer to our carbon troubles would materialize, as if by magic, at this point.

Most scientists, though, tend to sit in the middle: optimistic that science and technology will continue to push ahead, but not gambling on any particular game-changer. "You can't make those predictions," says Jae Edmonds, a scientist at the Joint Global Change Research Institute in College Park, Maryland. "What I do know is that you increase the likelihood of getting breakthroughs if you both invest in the underlying science and have policies that signal a limit on emissions. If you do that, it's reasonable to expect the technology to come."

That brings up another big question mark: Is there anything the government can do to quicken the pace of innovation, and convert those laboratory insights into commercial reality more swiftly? It's easy to point to the Manhattan Project or Apollo Program as examples where the government faced a seemingly intractable scientific problem, opened its checkbook, unleashed the nation's brightest minds, and watched the obstacles melt away. But that analogy is inapt. Michael Oppenheimer, a geoscientist at Princeton, has pointed out that the Manhattan Project was set up to create a unique product for a single customer-- the U.S. government--for whom money was no object. The government can't pursue the same strategy with energy, because price is a pivotal concern.

On this score, the government's record is murkier. Regulations like the Clean Air Act and fuel-economy standards have helped prod private companies to innovate, but shepherding major scientific advances from birth to commercial readiness is another matter entirely, and a difficult task. "It's a complicated, messy, recursive process," says Robert Fri, a former Environmental Protection Agency official who now works at the think tank Resources for the Future. "That's not always the way the government goes about doing stuff." Fri points to the Energy Department's synthetic fuels program in the 1970s, which struggled to invent a viable alternative to oil and fell apart when the price of crude sank back down. To be sure, Chu is aggressively pursuing new ways for the Energy Department to bridge this gap between basic science and the marketplace. He has read, among other things, a recent Brookings report arguing for closer collaboration among DOE's national labs, universities, and private industry, and he is trying to retool the Energy Department along similar lines. Those efforts are promising, but the results remain to be seen.

That doesn't mean it's time to despair. It may be difficult to translate Nobel-caliber insights into everyday household gadgets. But there's another job that the government has been fairly good at doing over the years: supporting technologies that are already viable but, for whatever reason, face barriers to gaining a toehold in the real world. "Historically, when the government has thought through what those barriers were, and targeted that barrier quite precisely, it could have a terrific positive impact," says Fri. In the 1970s, he notes, Energy Department labs realized that using electronic ballasts in fluorescent light bulbs could make the bulbs vastly more energy-efficient. The big roadblock was that, at the time, two ballast manufacturers dominated the market, and neither had any incentive to adopt the new technology, since if one did, the other would quickly follow, and no one would gain any market advantage- -they'd just have spent a bit more money. So the Energy Department seeded a few small start-up firms that demonstrated the ballasts and prompted the bigger companies to follow suit, leading to large savings for the public.

These deployment strategies, it turns out, can spur another type of innovation--marketplace learning--which can sometimes be just as crucial as cutting-edge scientific research. "There are three ways of lowering the cost of something," explains Romm. "There's a major technological advance; there are economies of scale; and then there's what's called the experience learning curve. The third one is arguably the most important--as you deploy stuff, you realize what needs to be improved. Where the stress fractures in a wind turbine are. How the mirrors [of a solar thermal plant] perform in a desert after a few months. Or in manufacturing--how you use silicon more efficiently, or make it thinner, or recycle it. None of this is Nobel-caliber." As existing technologies like wind turbines become more widely used, performance steadily improves, incremental research gets adopted, and the costs start falling--a process that can be more reliable than waiting for breathtaking new scientific advances. Studies of wind turbines, for example, have found that costs come down by as much as 17 percent each time production doubles, as a result of learning-by-doing.

That's a good thing, because it's this sort of incremental innovation that the planet may need to lean on most heavily, at least in the near term. A substantial body of evidence suggests that the world can make huge emission cuts in the next few decades without needing to wait for grandiose new technologies to arrive. In 2004, two Princeton scientists, Stephen Pacala and Robert Socolow, published a much-discussed paper in Science laying out 15 carbon-cutting strategies that have already been field-tested, which they dubbed "wedges." Solar power constituted one wedge, nuclear another, stricter fuel-economy standards for cars a third, reversing deforestation a fourth, and so on. The world, Pacala and Socolow showed, could cut emissions dramatically and still satisfy growing energy demand by deploying just seven of those wedges on a grand scale. (That's no mean task: One "wedge" of nuclear power, say, would mean building 21 new plants each year between now and 2050.) While some experts now believe we need even more wedges to meet the ipcc targets, several research efforts have reached similar conclusions: By combining everything we now have on hand, we can tackle a sizeable chunk of the problem at a reasonable cost. A 2008 McKinsey Global Institute analysis pegged the investments needed by 2030 at around 0.6 to 1.4 percent of global GDP and noted that the impact on the world's economic growth rate would be minimal, "even with currently known technologies."

The IPCC lists a wide array of technologies either available now or very likely to surface in the near future that could help reduce emissions. The former category includes (among other things) nuclear power, hydropower, wind power, geothermal, fuel-efficient vehicles, hybrids, biofuels, public transit, reforestation, and landfill methane recovery. The list of just-around-the- corner strategies includes carbon sequestration for coal-fired plants, advanced nuclear plants, tidal and wave power, cellulosic biofuels, and advanced electric vehicles. While no single solution will make more than a modest dent in the world's emissions--none of those items has the vast potential of, say, artificial photosynthesis--when combined together, they should steadily chip away at carbon emissions.

One particularly promising example is solar thermal power, in which large arrays of mirrors heat a liquid that can either generate electricity or be stored for when it's cloudy or dark. Such plants are being built now, and, if Congress passed a carbon price that made them more competitive with coal and natural-gas plants, they'd become even more prevalent and the price would continue nudging downward: The National Renewable Energy Laboratory has already estimated that these plants will be able to compete with existing natural-gas plants by 2015, and solar-power expert Ken Zweibel has estimated that they could, in theory, supply up to 69 percent of America's electricity by 2050. It would require a fair amount of government support and infrastructure investments, as well as further R&D, but not a whole new level of science. In the short term, meanwhile, one of the biggest reductions in emissions will come from making buildings and homes more energy-efficient, which typically requires no fancy new technology at all--just smarter regulations.

It's true that, eventually, existing technologies will hit a wall. If electric cars powered by lithium-ion batteries become widespread, for instance, then world lithium supplies could conceivably dwindle. Or, at a certain point, the need for cost-effective electrical-power storage could become a serious issue. (Right now, Denmark gets nearly 20 percent of its electricity from wind, but can only "store" that power by exporting the excess to Sweden and Norway, which send back hydropower when the wind isn't blowing-- a clever workaround that will prove less feasible as renewables spread.) "There are a bunch of things we know how to do now, and we want to use all the incentives we can to get those things out there," says Argonne's George Crabtree. "But, eventually, their impact will saturate, as soon as they're fully deployed--and that's where you'll need serious innovation."

By mid-century or so, we really may need the sorts of artificial leaves and futuristic batteries we can barely begin to imagine right now. And it is far less outlandish to expect that, by that time, science will be able to deliver such breakthroughs. But all of those sci-fi technologies decades from now won't mean much if we've long since blown past our carbon budget. That means doing as much as we can now--and fast.

If the news reports are accurate, Senator Ken Salazar of Colorado has been tapped by Barack Obama to head up the Department of Interior. Let's hope he knows what he's getting into. After the last eight years, the Interior Department has become fairly dysfunctional, and this may end up being one of the most difficult jobs in the Obama administration—not to mention one that gets remarkably little attention. 

Looking back historically, the Interior Department has been a mess from the very beginning. It was created in 1849 essentially to handle the government's odds and ends, from exploring the West to conducting the decennial census to managing the D.C. jail system, and quickly became a massive patronage reservoir: Walt Whitman was famously fired from the department in 1866 by a reformer secretary trying to weed out sinecures. The public-land giveaways in the 1890s were frequently plagued by fraud--a precursor to the Teapot Dome scandal under Warren Harding--and the Indian Bureau has been criticized for corruption and inefficiency for as long as anyone can remember. 

During the 20th century, as the urban population increased and Americans started caring about parks and conservation, the agency's mandate shifted away from simply handing off public land to extractive industries and more toward preserving natural resources. But regulatory capture at the agency has always been a problem. Carl Pope, the director of the Sierra Club, explained to me that in the 1970s, the environmental movement was focused on reforming the "Iron Triangle," in which regulators were dominated by the industries they were supposed to regulate. "With the Clean Air Act, the Clean Water Act, we were trying to break that triangle and create independent oversight mechanisms--like mandating public comments for new regulations," he said. But there was one place the reform movement left largely untouched--the Interior Department, which still operates under rules like the 1872 mining law, which still allows mining companies to stake claims in environmentally sensitive areas with little public comment. 

That means that more than most departments, what the Interior Department does really depends on who's sitting in the White House. Pope pointed out to me that, for instance, virtually all of the egregious EPA decisions under the Bush administration have been repudiated by the courts--such as its attempts to weaken mercury-emissions rules. But that's not the case for Interior, and never has been. During the Reagan years, James Watt was able to lease millions of acres of public land, weaken rules on oil and mining companies, and almost single-handedly rewrite strip mining laws. 

The current Bush administration has gone further still. Bush's Interior transition team, after all, included GOP lobbyist Jack Abramoff and stuffed the department full of former industry officials, many of whom were unqualified to do the conservation jobs they were given. The key figure early on was deputy secretary Steven Griles, an ex-mining executive who flouted ethics rules by conferring with former coal clients over mountaintop mining and coal-bed methane drilling. (His meetings were discovered by Kirsten Sykes, a young staffer at Friends of the Earth.) Griles was eventually ousted after the Abramoff scandal, when it was revealed that he had pledged to block approval for an Indian casino that Abramoff was fighting to kill while the lobbyist poured money into a front group run by Griles's girlfriend. (Griles later served ten months in prison for obstruction of justice.) 

During the Bush years, Interior officials catered entirely to miners, ranchers, and loggers--and paid virtually no attention to conservation. The tone was set from the beginning, when the Bureau of Reclamation diverted thousands of gallons from the Klamath River at the behest of farmers, despite scientific findings that the diversions would lead to massive kills of endangered salmon and suckerfish. (Later reporting revealed that Dick Cheney had pressured the department to divert the water.) Bush's first Interior secretary, Gale Norton, interfered with scientific assessments of the impact on Arctic drilling, suppressed a report on mountaintop removal mining, and refused to list a single new endangered species. 

Again, the difference with what was going on in the EPA was stark--Jeff Ruch of the Public Employees for Environmental Responsibility, whose group works with whistleblowers at both agencies, told me that at the EPA, scientific recommendations would simply be excluded from consideration by political appointees; at Interior, however, officials like Julie MacDonald, the deputy assistant secretary for Fish & Wildlife & Parks, would order the conclusions reversed. (MacDonald, semi-hilariously, resigned after it was revealed that, among other things, she was sharing internal agency documents with a teenage online gaming friend via his father's e-mail account.) 

Then, of course, there was the spectacularly sordid ongoing scandal at the Minerals Management Service (MMS), the federal agency that sells oil and gas collected as royalties from energy companies drilling on federal lands. As an inspector general's report revealed earlier this year, MMS employees were receiving thousands of dollars of gifts from the oil companies they were supposed to oversee. Stacy Leyshon, who had received $2,887 worth of meals, drinks, and golf passes from oil companies between 2002 and 2006, later allowed companies to revise their bids for oil after they had been awarded--118 amendments that cost the government $4.4 million. The manager of the royalty program was steering contracts to his outside consulting firm, all while buying cocaine from and sleeping with subordinates. This was all going on as taxpayers were being fleeced of billions of dollars thanks to royalty underpayments by oil companies, an undercovered scandal that has prompted a parade of suits by whistleblowers and auditors since the late 1990s.

Can Salazar clean out these stables? It helps that the Interior secretary has a lot of discretion to set the tone of the agency. During the Clinton years, then-Interior Secretary Bruce Babbitt helped tilt the balance back toward preservation, pioneering the use of "habitat conservation" plans under the Endangered Species Act, and negotiating a federal land-swap to set aside Utah's two-million acre Grand Staircase-Escalante a national monument. But there was a limit to how "green" the Clinton administration could and would get. Even Babbitt occasionally told staffers to rewrite endangered-species recommendations to avoid fights with landowners and developers. And Jim Baca resigned as head of BLM in 1994 after an internal revolt over attempts to raise grazing fees on ranchers to promote conservation. "They grew up in a culture that said that mining and logging and livestock was the reason they were there, so it was their job to make it very easy and inexpensive for those extractive industries to operate " Baca declared when he left. 

Salazar, for his part, is a relatively green pick. He has an 81 percent lifetime score from the League of Conservation Voters, and has been critical of the Bush administration's plans to expedite oil-shale drilling in Colorado and other Western states, on account of the environmental damage it would wreak. He's reportedly close to Obama, which will bolster his effectiveness, as will his longstanding ties to the American West. But he'll still have his hands full trying to balance the use of public lands with conservation, and overseeing everything from wildlife to mineral rights, from development to grazing. If his department begins listing endangered species that were neglected under the current administration, there will be an inevitable outcry from developers and landowners. He'll be under constant pressure to hand out oil and mining leases to companies accustomed to getting their way. And he'll be contending with agencies that are utterly broken, from MMS to the Bureau of Indian Affairs. Jeff Rosen recently wrote in The New Republic about how whoever heads up the Department of Homeland Security will have perhaps the single most impossible job in the Cabinet. Salazar may have just landed the runner-up.

The first hundred days of any presidency rarely go off as planned, but, for now, Barack Obama seems to know what's at the top of his to-do list. In late October, he told Time's Joe Klein that "a new energy economy" would "be my number-one priority when I get into office." But then, as if to cut off a lurking objection, Obama quickly tacked on a qualifier: "assuming, obviously, that we have done enough to just stabilize the immediate economic situation." The caveat seemed to nod at a nascent conventional wisdom: Now that the United States is staring down the barrel of a nasty recession, many Washington types wonder if Obama will have to tear up that to-do list and rein in his ambitious climate and energy proposals.

True, not all of Obama's green ideas are controversial: You can't pick up a newspaper op-ed page these days without seeing yet another economist argue that government spending on clean energy and eco-friendly infrastructure could provide the Keynesian boost necessary to haul the economy out of its mire. But the linchpin of Obama's energy platform wasn't new spending; it was an economy- wide cap on carbon-dioxide emissions, in which a decreasing number of tradeable pollution permits would be auctioned off each year, so as to ratchet down greenhouse gases and help avert drastic global warming. Energy experts tend to agree that it's not enough for the government to fund alternative-energy sources; the only way to usher in the "new energy economy" Obama envisions is to make it costlier to burn fossil fuels. But that's the catch: Since Obama's cap-and-trade proposal would essentially act as a tax and increase the price of oil, gas, and coal, he downplayed this aspect of his plan on the trail--and it's the one idea that now looks most vulnerable. As House energy and commerce chair John Dingell recently told The Wall Street Journal, "In times of economic downturns, members [of Congress] are extremely reluctant to add burdens to the economy, and we're going to confront that problem."

The queasiness is understandable. On the surface, it really doesn't sound like a hot idea to impose broad new regulations on a struggling economy. In this case, though, the fear is misguided. Global warming is urgent enough that the next administration will need to go all-out on the issue, passing not just a green stimulus package but especially a cap on carbon. And, not only is the recession a poor excuse to hold back, it may even be all the more reason to act.

If there's any upside to a recession (and it's hardly much consolation), it's that the accompanying decline in energy use gives us some breathing room to meet long-term emissions targets. (The rough consensus among climate scientists is that the world should aim to cut greenhouse-gas emissions 50 percent below 1990 levels by 2050, a goal that sounded increasingly preposterous in recent years as countries were belching up carbon dioxide at a pace exceeding even the direst forecasts of the Intergovernmental Panel on Climate Change.) The downside, however, is that the fall of oil and gas prices is forcing investors to shelve alternative-energy projects: The WilderHill index of clean-tech stocks has tumbled more than 50 percent since September, and even T. Boone Pickens is putting aside his beloved wind farms for now. The main reason the solar and wind industries aren't facing total collapse is government policy: Some 30 states have laws requiring utilities to get a fixed percentage of their electricity from renewable sources by a certain date.

More problematic still, a recession makes it trickier for politicians to contemplate new environmental rules. Conservatives like Oklahoma Senator James Inhofe have been thundering that an emissions cap--or any policy that raises the price of carbon--will be the death blow for an already atrophying economy. Now, climate-change skeptics are always saying that carbon caps will put us in the poorhouse, recession or no. (Last year, when the economy was still chugging along, the Chamber of Commerce aired an anti-cap-and-trade ad showing a family forced to cook breakfast by candlelight and huddle together in bed for warmth.) The question is whether Obama should pay these naysayers more heed during a slump, or whether he should follow the example of European leaders like Nicolas Sarkozy, who, despite the financial crisis, are working to tighten the EU's emissions-trading regime.

As it turns out, a recession isn't a bad time to get started on climate legislation. Even if Congress raced to pass a cap-and-trade bill in 2009, it would take some time--likely a few years--just to set up a complex new regulatory regime. Moreover, as David Wheeler, a climate-policy expert at the Center for Global Development, points out, an economic slump actually offers a prime opportunity to start trading: If Congress sets the initial economy-wide cap at pre-recession levels, then pollution permits will be exceedingly cheap as long as the economy--and hence energy use--is still shrinking. (Indeed, the downturn in Europe has caused the price of carbon to hit rock-bottom levels.) This would give companies time to learn the system and plan for the future without being assailed right away by high prices.

Congress could then use the interim years to go full speed ahead on a green stimulus package. Both Obama and Al Gore have stressed the need for a new electric grid that could link up to faraway wind and solar farms and better manage electricity demand. It's a good idea: According to a new report by the North American Electric Reliability Council, any attempt to make major emissions cuts could put unbearable strain on the grid unless it's revamped. Other programs to boost the energy efficiency of the economy--retrofitting buildings, say, or capturing and using waste heat from factories--are also needed. All these measures would help utilities and businesses make reductions more cheaply once the cap does start clamping down.

Granted, no cap on greenhouse gases will be totally cost-free. But it's important to be clear about what those costs really are. One recent survey of five respected economic models from academic and government groups found that cap-and-trade policies like the Lieberman-Warner bill considered by Congress this summer would shave off about three-hundredths of a percentage point of the country's annual GDP growth. (The size of the U.S. economy, in other words, would reach $26 trillion in April rather than January of 2030.) Jay Apt, a professor at Carnegie Mellon's Electric Industry Center, explains that the bulk of cuts under a cap-and-trade regime would likely come from the country's electric utilities--and he estimates that the electric-power sector could avoid or capture 80 percent of its emissions for about $65-$90 billion per year, on average. That, he notes, is comparable to the cost of compliance at the peak of the original Clean Air Act, which, contrary to doomsday predictions from industry lobbyists, didn't put any noticeable dents in the economy. (The law did, however, help midwife new businesses that sold scrubbers, particulate matter filters, and flue gas desulfurization technologies to the rest of the world.)

Of course, it's one thing to suggest that emissions restrictions won't be half as crippling as opponents claim, but is it possible that cap-and-trade could actually bolster the economy? Perhaps. If, for instance, the revenues raised by auctioning off pollution permits were rebated to consumers, most families could see their incomes rise, according to one University of Massachusetts study. What's more, the certainty that clear rules on carbon are finally on the way could help get private investment flowing again. As Chuck Gray, the executive director of the National Association of Regulatory Utility Commissioners, explained, "climate-change legislation is essential no matter what the economic situation," because "it will remove many of the uncertainties that are preventing state regulators, utilities, and others from planning and financing new electricity investments." Venture capitalists have lately been dipping their toes in the clean-tech pool--investing $2.2 billion in more than 200 deals in 2007--but many financiers, as a recent New York Times Magazine story made clear, are still waiting for a more supportive policy framework to emerge. Sounds like cap-and-trade should be at the top of someone's to-do list after all.  

It’s difficult to think of a skyscraper--the ultimate inanimate object--as having much to do with environmentalism. But the concept of green building has arrived--if not front and center in Washington, at least in the minds of a diverse coalition of green activists. As part of TNR TV’s series on contemporary environmentalism, this episode explores how the concept of sustainable design has leapt from the pages of glossy magazines like Vanity Fair to the long-term planning of corporations, real estate developers large and small, and an increasing number of everyday Americans.

Most surprising about the rise of green building is its rare, Wall Street-to-Main Street synergy, which acknowledges that, as Doug Gatlin of the U.S. Green Building Council (USGBC) put it, green building is “good for business and good for the environment.”

Capital costs for green building are still somewhat elevated, but innovative schemes to make green building accessible are growing. This includes public housing projects like Melrose Commons in the Bronx, featured in this video, but also initiatives like those of the New York State Energy Research and Development Association, designed to train thousands more in the nuances of green building. Similar initiatives in education, government, and the private sector will rapidly accelerate the pace of innovation and the ability of businesses and homes to choose green. Further, deploying an army of energy auditors to small businesses and mixed-use real estate developers across the region will provide well-paying, high skilled employment opportunities.

As Carlton Brown and numerous others told me, in a bad economy--particularly one where real estate prices are in freefall and new construction is flatlining--worries about sustaining the jobs and economic productivity in this sector (again, 20 percent of American economic activity) are paramount. As if on cue, the USGBC recently rolled out a new set of standards and practices based on LEED, this time for existing buildings. Green jobs advocates aim to reduce emissions while providing family-sustaining employment; the USGBC’s recommended retrofits (for example, plugging leaks via weatherization, top-line insulation, and window treatments) offer the chance to do just that, keeping the trades humming even as the U.S. economy creeps toward recession.

Click here to watch Olopade's video exploring the efforts of environmental activists in the South Bronx trying to changer the color of "green." Click here to see Olopade's conversations with environmental activist Kate Gordon and policy specialist Bracken Hendricks as they discuss whether "green jobs" can actually help solve the current economic crisis.

As the age of cheap oil comes to a close, it's springtime for gloomy futurists. Visions of a brutish world marked by violent squabbles over dwindling reserves, of junkyards littered with abandoned cars, of suburban slums overrun by weeds, of the collapse of industrial agriculture--none of this sounds as outlandish as it once did. Still, most of these horror stories are likely overstated: Energy experts tend to agree that, with a little ingenuity and a generous helping of political will, we could transition away from fossil fuels without being forced to give up our modern lifestyles.

But there's one big exception--an area where a post-carbon world really could mean a radical shift in the way we live. That's the world of commercial flight.

Early signs of an aviation apocalypse are already upon us. As oil prices flirt with $130 per barrel and the dollar struggles, airlines are paying nearly 80 percent more for fuel than they did a year ago. Twenty-five airlines have gone belly-up this year--three to four times the usual yearly rate. Major carriers like American, Northwest, and United, still reeling from the industry downturn after September 11, go barely a month without announcing layoffs and capacity cuts.

And it gets worse from there. Despite recent fluctuations, a growing number of economists are bracing for oil to hit or surpass $200 per barrel in a few years, and most industry analysts agree with Douglas Runte, of RBS Greenwich Capital, who told The Wall Street Journal in June, "Many airline business models cease to work at $135-a-barrel oil prices." After all, most airlines barely figured out how to be profitable in a world of low fuel costs. Jeff Rubin, chief economist of Canadian investment bank CIBC World Markets, has predicted that gasoline will hit $7 per gallon by 2010, forcing some 10 million cars in the United States off the road. If that happens, he told me, "You're going to see an even bigger exit in the airline industry."

As if one plague wasn't enough, the threat of climate change could mean further doom for airlines. In Great Britain, green groups are lobbying hard in favor of aviation fuel taxes and against a proposed third runway at Heathrow Airport, wewhile activist groups, like one called Plane Stupid, have taken to unfurling banners from atop Westminster Palace and elsewhere with slogans like WE FLY, WE DIE. They argue that, at a time when greenhouse gases are pushing global temperature to perilous levels, flying--one of the most energy-intensive forms of travel around--is a luxury the planet simply can't afford. (While aviation currently accounts for just 3 percent of man-made carbondioxide emissions, it's one of the fastest-growing sources, and the true climate impact of flight is around 2.7 times that of carbon dioxide alone, thanks to the added warming effects of nitrogen-oxide emissions and jet contrails.)

As a result of this advocacy, a social stigma against flying is slowly spreading across Europe. While air travel isn't covered by the Kyoto Protocol, the next round of climate-treaty talks will likely address the issue, and the EU has recently announced that it will bring aviation into its emissions-trading regime--forcing airlines to pay for 15 percent of their carbon use starting in 2012. "That's the real deal," says Bill Swelbar, a research engineer at MIT's International Center for Air Transportation. "When you look at some of the taxes and fees being discussed in Europe, we might as well bankrupt our industry today." John Whitelegg, a transportation expert at York University's Stockholm Environment Institute, estimates that requiring airlines to pay the full environmental costs of flight could raise fares as much as five-fold.

Few of the analysts I interviewed wanted to venture predictions about aviation's end of days. One far-reaching scenario, however, was put forward by Anthony Perl and Richard Gilbert, two Canadian transportation experts who, in their new book Transport Revolutions, envision a world in which rising oil prices have reduced domestic flying in the United States roughly 40 percent by 2025--even assuming that airlines improve fuel efficiency by about 50 percent. In such a scenario, the United States could go from having nearly 400 primary airports down to 50 or so; instead of dozens of flights each day between New York and San Francisco carrying 200 people apiece, there might be only a handful carrying 800 or more in new extra-jumbo jets.

The Federal Aviation Administration, for its part, remains bullish on flight, predicting that U.S. airlines will carry 1.3 billion passengers by 2025, nearly double the current number. But even the FAA is starting to soften its outlook, since, already this year, fares in the United States have risen nearly 15 percent on average and some 2.7 million fewer people are expected to fly this summer than last. American Airlines has announced a 12 percent cut in domestic capacity for the rest of the year; United Airlines, a 16 percent cut. Regional jets--smaller planes carrying fewer than 50 passengers that account for one-fourth of all flights today--are being grounded en masse. In the short term, cuts may prove healthy for many airlines, letting them scale back to profitable core markets. But, if oil prices do soar past $200 per barrel, major carriers could start downsizing sharply, abandoning more routes and smaller hubs, and even going out of business for good.

Maybe the gloomy futurists have a point after all, and mass aviation could be coming to an end. No longer would air travel be like the Internet or television--a cheap technology available to virtually anyone, shaping our world in countless little ways. If that happened, the result would mean more than just the end of easy weekend jaunts to Bermuda or annual Christmas visits home. It could mean major shifts in the economy, changes in immigration patterns across the world, and perhaps even a remapping of the planet as we know it.

In the 1950s, flying was a special event: You could hardly find a ticket from New York to Europe for less than $5,000; men put on suits, women wore hats and heels, and some of the luxury planes, like Pan Am's Clipper, had bridal suites, dining salons, and beds. But, in the late '70s, under pressure from consumer groups and business interests, Congress deregulated the industry, allowing upstarts to open up new routes more easily and compete on price, ushering in the modern age of mass aviation. Between 1975 and 2005, inflation-adjusted airfares in the United States plunged some 40 percent, while the annual number of passengers more than tripled. A similar shift swept across the Europe in the '90s, as deregulation gave rise to popular "no-frills" carriers like Ryanair and Easyjet. By 2001, The Atlantic Monthly was envisioning a dawning age of "air taxis"--small planes that would make flight as quotidian as hailing a cab.

Deregulation had its costs: Airlines ditched amenities and service to offer rock-bottom fares; congestion and delays plagued travelers; and the industry itself became tempestuous for individual companies and their workers. Yet these seemed like minor sacrifices for the democratization of flight, as middle-class travelers were able to visit places once accessible only by books. Attractions changed: Small museums and historic sites tucked away on interstates began to collect dust, while popular hotspots like Cancún and Waikiki became choked with tourists.

Other sociological changes wrought by cheap air travel have also been striking. Since 1980, the number of international migrants has doubled to nearly 200 million, as skilled workers and low-wage immigrants alike, knowing they could affordably return home, became more willing to set off for foreign shores. Within Europe, low-budget airlines like the Hungarian carrier Wizz Air will transport Poles and Hungarians to Western Europe for as low as $26, which has enabled a surge of Eastern European migrant workers into the United Kingdom--most of whom stay for less than three months, according to a recent study by the Institute for Public Policy Research in London. "You'll have, for instance, a Polish doctor who spends most of his time in Poland but commutes to Scotland for a long weekend shift when most Scottish doctors aren't working," says Danny Sriskandarajah, who co-authored the report. "That would've been unheard of five years ago."

In large countries such as the United States, cheap airfare has helped facilitate the geographic dispersion of families and businesses alike. In the 1980s, some onlookers predicted that these trends would spell the demise of large urban centers. That never happened--there are still advantages to agglomeration--but new patterns did emerge. Academics took it for granted that they could toss around ideas with far-flung colleagues at conferences. Trade shows and conventions attracting millions changed the way business was conducted. For a growing subset of college grads, traveling abroad became a way of "finding themselves" before settling down. Long-distance relationships became commonplace--one recent survey in Europe found that three million Brits were looking for love abroad rather than at home, as flying to the continent for dates was just as cheap as taking trains around Britain. Of course, there was a dark side, too: Democratic air travel created new opportunities for terrorism and, as the 2003 SARS epidemic made clear, new pathways for the rapid spread of disease.

More important, if less evident, was the air-freight revolution of the 1980s, as companies like Federal Express bought up planes and transformed logistics and shipping in the United States, creating a system that sped up deliveries, gave the economy vast new flexibility, and fueled the rise of Internet distributors like Amazon and eBay. Air freight now plays a huge role globally, carrying, for instance, one-third of the value of all U.S. imports. And the system relies heavily on cheap fuel: Every night, FedEx keeps a number of empty planes up in the air, to better respond to requests at a moment's notice.

Airports themselves, rapidly expanding both in number and size, have become engines of urban growth. At the extreme end sits Brasília, which was not only conceived in the 1950s as both a capital and a major air hub, but had its first building materials flown in by air and was designed to look like an airplane from above. But airport-driven development is increasingly common in the United States, as well: John Kasarda, a University of North Carolina business professor, has coined the term "aerotropolis" to describe the mini-cities that have grown up around airports, bringing in first hotels for business travelers, then office parks packed with pharmaceutical and tech companies that need to ship out their products quickly. In the '80s, Dallas-Fort Worth's status as a major air hub brought in hundreds of thousands of distribution and manufacturing jobs, along with a conglomeration of high-tech firms that now rivals Silicon Valley.

Even in the most pessimistic scenarios, the social changes wrought by cheap airfares are not going to run perfectly in reverse, like the bombing of Dresden in Slaughterhouse Five. Kasarda, for instance, is skeptical that even large increases in fuel prices will mean the end of aerotropolises, which have become largely self-sustaining. But what if a hefty decline in air travel is upon us? What would that mean?

To start with, flight may become once again largely confined to a more elite jet-setting class. The rest of us may have to vacation closer to home: Even the relatively modest 30 percent dip in air travel after September 11 proved a boon to old-fashioned local attractions like the Texas State Fair and the Bronx Zoo. And many people may think twice about relocating a flight away from family members. "It will involve a shift in people's decisions of whether they have to move," says Vered Amit, a professor of anthropology at Concordia College who studies transnational mobility. "If people are separated for longer, don't see each other as often, it's going to hurt."

Immigration, meanwhile, did not begin with the birth of Easyjet, but some migration flows could cool off--the 465,000 Poles who have flown off on low-cost carriers to work in the United Kingdom since 2004, for instance, or the 70, 000 Filipinos who migrate to the United States each year, or the Caribbean workers, skilled and unskilled alike, who fly frequently up to North America, often maintaining homes in both places.

As for the economy, no doubt a number of business fliers--who account for roughly one-third of all air travelers--will start teleconferencing instead. (Those who do still fly will enjoy the drops in both congestion and delays that come with capacity cuts.) Air freight could be harder hit, which may mean, among other things, that Americans can no longer walk into a Whole Foods in January and find blueberries flown 12,000 miles from Tasmania. During the early '90s, local produce distributors were heralding the fact that air freight had nearly quadrupled the number of items available in U.S. supermarkets. Perhaps not for much longer.

As people stop crossing the globe so frequently, the landscape will change, too. Popular tourist resorts accessible mainly by air, like Orlando and Las Vegas, could decline--much as, ironically, Atlantic City did in the latter half of the twentieth century, when air travel made it easier for East Coasters to fly off and gamble in the Nevada desert. The entire state of Alaska--whose denizens have been called "the flyingest people under the American flag"--would be dramatically altered if the small planes dotting the small airports and frozen lakes across the state could no longer afford to fly quite so often.

Dismal fates could await areas with high per capita concentrations of airport employment, such as Dallas-Fort Worth, Miami, and Tucson. Jack Kyser, chief economist for the Los Angeles County Economic Development Corporation, points out that some California cities like Fresno have managed to attract business by promising easy air access from L.A. in precisely the sort of regional jets that are now endangered. And what about the airports themselves--which, as the greens engaged in pitched battles at Heathrow remind us, were often financed based on projections of near-infinite growth and $60-per-barrel oil? Will many of them become, as one industry analyst quipped to me, "half-empty mausoleums"?

Small towns will be especially vulnerable to losing scheduled air service. That's already happened to nearly 30 U.S. cities in the past year, from Wilmington, Delaware (population 72,000) to Boulder City, Nevada (14,000). Hagerstown, Maryland, lost all commercial air service recently, rendering its new $61.8 million, 7,000-foot runway useless. Some of the towns in danger--like Massena, New York, nestled along the Canadian border--lie nowhere near four-lane highways and have been connected to the outside world primarily by airplanes, which they rely on to bring in business clients or take residents to medical centers. One local official in northern Wisconsin recently offered to Milwaukee Magazine a theory on the influx of new residents who don't mind the harsh winters: "They know they're not stuck here. They can fly out for a month or two."

For now, the federal government picks up a large part of the tab for flights to roughly 140 smaller communities with its Essential Air Service Program, which costs $110 million per year and provides subsidies as large as $1,300 per passenger. As fuel prices rise, Congress will have to decide if it wants to directly bankroll ever larger portions of the air network.

Meanwhile, even worse troubles might afflict the developing world, where the global tourism industry brought in $205 billion in 2005; many poorer countries, like those in the Caribbean, have tourism-based economies that depend on cheap air travel. True, there are parts of the world under heavy environmental strain from stampeding tourists--the Gálapagos Islands were recently added to UNESCO's "danger list." But a decline in flight-based tourism could also hurt local ecologies as governments, seeking to replace lost tourist cash, raid their own natural resources: In Ethiopia, for instance, Germany recently funded an eco-tourism project to forestall illegal logging in the Bale Mountains.

Is there a way to avoid this fate? I reached Richard Gilbert, one of the analysts warning of a potentially drastic decline in U.S. air travel over the next two decades, as he was returning from a meeting in Toronto with the U.S. Transportation Research Board, a government research body. I asked him what sort of response he gets when he discusses his book with industry insiders. "You see three arguments," Gilbert told me. "One is that ingenuity, American or otherwise, will overcome the problem in terms of oil prices. The second is that we'll wrestle it to the ground with technology. And the third type of response--and this one doesn't have a specific argument--is that this just can't happen."

It's always dangerous to bet against human ingenuity. But, while most of the technology needed to replace gas-guzzling cars with, say, plug-in hybrids either exists or sits just over the horizon, decarbonizing air travel is a much harder prospect, not least because of the massive amounts of energy needed to lift a large passenger plane in the air. The industry has already boosted the fuel efficiency of jets 70 percent in the last four decades, and is now left sanding down the rough spots--tinkering with ultralight materials, flying more slowly, or even charging passengers for extra bags. Propeller planes use less fuel than jets but are only really viable for some short-haul flights. Engine manufacturers say that more advanced technologies like fuel cells and carbon capture are still technically infeasible, while "blended wing" designs--planes shaped like stealth bombers to reduce drag--have barely left the drawing board. Improvements in air-traffic control will reduce both the length of flights and fuel-wasting delays, but may not be enough to surmount $200-per-barrel oil.

Virgin Airlines CEO Richard Branson has held out high hopes for jet biofuels, though spikes in food prices and massive deforestation have dimmed ethanol's star. Someday we may get solar-powered jets or hydrogen fuel cells, but, as the Intergovernmental Panel on Climate Change concluded in its landmark 1999 aviation study, "There would not appear to be any practical alternatives to kerosenebased fuels for commercial jet aircraft for the next several decades." The military may be one exception: The Pentagon, worried about peak oil scenarios, has pushed to fuel its Air Force with liquefied coal, which may keep fighter jets aloft, but would have horrifying climate consequences if used on a broad scale.

That means, in the next few decades, high-speed trains-which require considerably less energy per passenger than airplanes--may prove the most viable alternative to flight. York University's Whitelegg notes that, in Europe, trips shorter than 300 miles make up about 45 percent of all flights; most could be traversed nearly as quickly by train, if the proper infrastructure were built. Hank Dittmar, CEO of the Prince's Foundation for the Built Environment, sees airports morphing into "travelports" that seamlessly link rail and air networks, with the latter used largely for long-distance.

Trains, of course, can't span oceans. Perhaps the most unlikely alternative to emerge in recent months is the rebirth of the dirigible or airship, as companies have already been unveiling new designs for niche tourist trips and transporting cargo. The good news is that modern helium airships are far safer than the Hindenburg and emit a great deal less carbon than jumbo jets. The bad news is that natural reserves of helium may be running low and, more to the point, airships can't carry many people at a time, don't handle heavy weather well, and are quite slow: A flight from New York to London would take around 40 hours. (Fast passenger ships would take twice as long, though modern ocean liners suffer in peak oil scenarios, too.)

In an age when American consultants can commute weekly by air and return home to their spouses on the weekends, or when Manchester United soccer fans think nothing of hopping on a flight to follow their team for a quick game in Turin, it's almost impossible to imagine a world in which employers gave workers, say, three weeks off so that they could board a modern-day zeppelin and float home for the holidays. As even George Monbiot, the British environmentalist who has thundered most furiously about the need to downsize air travel in order to stave off drastic climate change, concedes, abandoning the age of mass aviation would be a hugely disorienting change. "It flies in the face of everything we have been encouraged to regard as progress," he has written. But the end of oil, or the urgency of global warming, or both, could well force that change upon us. Is that something our world, increasingly accustomed to its frenetic, globe-trotting pace, could handle?

Bradford Plumer is an assistant editor of The New Republic.