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Some private health care systems are also studying vaccination failures among employees that will yield useful data, she said, though such studies are not necessarily reflective of broader trends.

It’s such a rare phenomenon, and it doesn’t change the trajectory of the pandemic,” said Dr. Amesh A. Adalja, a senior scholar at Johns Hopkins Center for Health Security.

he is still not back to her daily three-mile runs with her dog because of shortness of breath. “I’m young, 43, healthy, with no pre-existing conditions, but you often find me now on the couch resting,” Ms. Cohn said

t Rockefeller University, which routinely tests students and employees for the coronavirus, breakthrough infections were identified in two women who had been fully vaccinated and had developed robust immune responses after inoculation, according to a study published in The New England Journal of Medicine.

Many scientists agree: collecting more data is always preferable to collecting less. “The virus is constantly changing, and we need to stay three steps ahead of it,” said Michael Kinch, an immunologist and associate vice chancellor of the Centers for Research Innovation in Biotechnology at Washington University in St. Louis.

More than 10,000 of the 101 million people who were fully vaccinated as of April 30 caught the virus, according to a recent CDC report.

If scientists can't sequence genes from the virus, there's not much chance these people are contagious, and there's not much scientists can learn about the virus by studying them, the CDC and other researchers say.

Investigating the full spectrum of breakthrough infections could provide crucial information, including clues about whether some vaccines are working better than others and whether breakthroughs are happening more in some people than others, Bright and others say.

"These variants are spreading, and if you're just looking at the small percentage, then you're really missing the big picture,"

Careful study of breakthrough infections also could provide useful information for improving the vaccines as well as revelations about possible long-term health effects of these infections on people who don't initially develop symptoms or only become mildly ill.

At least some of those studies include examining the role of variants, according to Dr. Jennifer Verani, who's helping lead the CDC's vaccine effectiveness team.

Barack Obama’s administration, accelerating a process that had begun in the early 1960s under President Kennedy, was centralizing foreign-policy decision making in the White House’s National Security Council, marginalizing the State Department.

Finally, Kerry, a defeated presidential candidate, was devoid of the sexiness that automatically attaches to a figure, like Hillary Clinton, who remains a legitimate presidential prospect

The consensus in Washington was that Kerry was a boring if not irrelevant man stepping into what was becoming a boring, irrelevant job.

Nearly a year into his tenure, Kerry is the driving force behind a flurry of Mideast diplomacy the scope of which has not been seen in years. In the face of widespread skepticism, he has revived the Israeli-Palestinian peace process; brokered a deal with Russia to remove chemical weapons from Syria; embarked on a new round of nuclear talks with Iran, holding the highest-level face-to-face talks with Iranian diplomats in years; and started hammering out a new post-withdrawal security agreement with Afghan President Hamid Karzai.

it will be Kerry who is credited with making the State Department relevant again.

“He’s front and center on all these issues. That clearly represents a very ambitious first year for any secretary of state.”

Kerry has a bad habit of wandering off script. On a trip to Pakistan in August, he created two diplomatic incidents in a single interview. First he said that the Egyptian army was “restoring democracy” when it toppled the country’s democratically elected president.

President Obama had “a timeline” for ending U.S. drone strikes in Pakistan.

he overshot in the opposite direction, promising that any American strike against Syria would be “unbelievably small”—a bit of impressively self-defeating rhetoric that undermined days of administration efforts to argue that a few dozen Tomahawk cruise-missile strikes would be more than what hawkish critics were calling a pointless “pinprick.”

a word that comes up frequently in conversations about Kerry is gasbag. He had few close friends in the Senate, where he served for nearly 30 years. A former diplomat says Kerry’s recent foreign-policy successes have made him more insufferable than ever.

his gaffes are caused by arrogance and indiscipline. They say that even in a city swollen with egotism and pomposity, Kerry stands out.

“Nobody would challenge the notion that he’s been very much a team player and willing to take on really hard assignments from the president and go to the toughest places.”

(In one late-night press conference in Moscow last May, he uttered a staggering 95-word sentence.

“Even as a junior or senior, he was a pompous blowhard,” says someone who attended Yale with Kerry in the 1960s and asked not to be named.

he is not so much arrogant as awkward.

Liberal Democrats call his hawkish views on Syria a betrayal of his antiwar past. Republicans say he is a perennial flip-flopper: he fought in the Vietnam War and then protested against it; he supported the 2003 invasion of Iraq and then opposed it; he tried to negotiate with Bashar al‑Assad in 2009, then compared him to Adolf Hitler—and then reopened the door to negotiating with him again.

Kerry “just can’t dance.”

Washington mandarins dismiss Kerry’s foreign-policy ambitions as grandiose and overweening, especially relative to what America’s diminishing power can achieve after Iraq and Afghanistan

old foreign-policy hands say that instead of acknowledging the limits of American power in the post–Arab Spring Middle East, Kerry looks for misguided ways to apply power the country no longer has.

Current aides argue that Kerry’s recent successes belie the caricatures of him. “Show me where he hasn’t done this job well,” one demanded when I interviewed him in mid-October.

“I would ask John Kerry, ‘How can you ask a man to be the first one to die for a mistake?’ ”

Kerry seem “pompous” is that “oftentimes he tries too hard.” According to Manley and others, Kerry had a knack for walking up to fellow members on the Senate floor at precisely the wrong time.

His enormous ambition motivates him to aim for major breakthroughs despite daunting odds. And his healthy self-confidence allows him to believe that he can convince anyone of virtually anything.

Kerry also has bottomless reserves of patience that allow him to engage for hours in seemingly fruitless negotiations; he persists long past the time others would have given up in exhaustion.

The amount of time he’s spent negotiating with Afghanistan’s Hamid Karzai and Russia’s Sergey Lavrov alone should qualify him for some kind of diplomatic medal of honor.

an indifference to his own political standing.

Political calculations may have constrained the risks Hillary Clinton was willing to take. Kerry, in contrast, no longer needs to heed political consultants. Nor does he need to worry too much about what his detractors say.

“I don’t care at all,” he said. “I could care less about it. You know, David, I ran for president, so I’m not scared of failure.”

secretary of state is the job for which Kerry was born and bred

“I’m not worried about the politics,” Lowenstein recalls Kerry telling him. “I want to get things done.”

Obama, too, no longer has to worry about reelection; concerns about the 2012 election may have limited the president’s own appetite for diplomatic risk taking in the Mideast during his first term.

But his enthusiasm for his current job is unquestionable; one aide told me that he will have to be dragged from the office—fingernails scraping against the floor—at the end of his term.

As a presidential candidate, he had to downplay his obsession with foreign policy and his fluency in foreign languages, for fear that such things would play badly with voters; as secretary of state, he can freely leverage those qualities.

if there is no breakthrough with Iran, or if his efforts to broker peace in Syria fall short, or if the Israeli-Palestinian peace talks founder, history will likely view Kerry as the tragicomic figure his detractors already judge him to be.

“After you lose the presidency, you don’t have much else to lose.”

Following stints as an assistant district attorney and the lieutenant governor of Massachusetts, Kerry would, after his election to the Senate in 1984, go on to serve for 28 years on the same committee he had stood before in 1971, the Senate Foreign Relations Committee

(But for Ohio, where he lost to Bush by 119,000 votes, Kerry would have been president.

But Kerry stepped into the role at a singularly weak moment for the position. For one thing, America, weary after a decade of conflict, is turning inward; activist diplomacy is out of favor. For another, State Department employees I interviewed told me that morale is low.

the department is too hierarchical, inflexible, and risk-averse—and is in danger of becoming even more so in the aftermath of Benghazi.

the intensely controlling Obama administration has centralized foreign-policy decision making in the National Security Council, weakening the State Department.

Just a day after Kerry delivered one of the most impassioned speeches of his career, assailing Assad’s use of chemical weapons on civilians as a “crime against conscience” and sending a clear signal that U.S. air strikes on Syria were imminent, the president announced that missile strikes might in fact not be imminent, and that he would be seeking congressional authorization to attack Syria.

the president risked causing foreign leaders and negotiators to doubt whether any future warnings or statements issued by Kerry were backed by the White House.

Kerry conducted long interviews with every living former secretary of state—Kissinger, George Shultz, Baker, Madeleine Albright, Powell, Condoleezza Rice, and Clinton—and set out to model himself after Shultz, who, in six and a half years serving under Ronald Reagan, was seen as a combination of the two prototypes, both a great diplomat and a good manager.

“I don’t care about risk, honestly,” he said, leaning forward in his chair, spoiling for a fight. “The riskiest thing to do is to not act. I would far rather try and fail than fail not trying.”

When off the record, in relaxed settings, he is refreshingly direct, profane, and insightful, speaking bluntly about the limits of American power and caustically lamenting Washington’s growing paralysis and partisanship

He finishes sentences with phrases such as something like that or that’s about it or thanks, man. Toes tapping, head bobbing back and forth, he speaks with fervor and candor. His tenacity is palpable.

Recent secretaries of state have had different strengths. Henry Kissinger and James Baker, two secretaries who had close relationships with their presidents (Nixon in Kissinger’s case, George H. W. Bush in Baker’s), were powerful bureaucratic players.

But isn’t staking America’s credibility, and his own reputation, on long-odds breakthrough agreements with Tehran or Moscow, or on Israeli-Palestinian peace talks, a dubious exercise, as Obama’s failed first-term efforts at Mideast peace demonstrated?

Colin Powell lost a crucial internal administration battle in failing to halt the Bush White House’s march to war in Iraq—but was adored at the State Department for implementing sweeping administrative reforms.

Clinton embraced a new, Google Hangout era of town-hall diplomacy, and she elevated economic development and women’s issues. She was an architect of the administration’s “pivot to Asia,” and she took risks in supporting the Afghanistan troop surge and the intervention in Libya.

steered clear of the Middle East, delegating special envoys like Richard Holbrooke and George Mitchell to grapple with the Israeli-Palestinian peace process, peace talks with the Taliban

Clinton was much more prudent and careful than Kerry, whom one former State Department official describes as more of a “high-risk, high-reward”

“My view is that she was pretty sheltered,” he told me. “They were not interpersonally pleasant, and they were very protective of her. You can get into a cocoon.”

“My assessment was that she made a calculated political choice not to hang her hat on that thankless task,” Kim Ghattas,

the former secretary would have taken bolder risks but was reined in by the White House—especially during her first couple of years in office, when hostility from the bitter 2008 primary campaign still lingered between the Obama and Clinton staffs.

she actively engaged in Middle East talks, at one point meeting with Israeli Prime Minister Benjamin Netanyahu for seven hours in New York.

Kennan warned Powell about the dangers of traveling too much—of prioritizing activist diplomacy over providing the White House with solid foreign-policy analysis.

Powell gave a copy of Kennan’s letter to Kerry. So far, Kerry is not following the advice. As October came to a close, Kerry had already flown more than 213,000 miles and spent more than 100 days—roughly 40 percent of his time—outside the United States. In his first nine months, he’d traveled more miles than Clinton had in her entire first year in office.

In 2009, he convinced Afghan President Hamid Karzai to consent to a runoff in his country’s disputed presidential election.

2011, he was dispatched to Pakistan after the killing of Osama bin Laden to persuade local officials to return the tail of an American helicopter that had crashed at the site.

cemented Kerry’s bond with Obama was less his diplomatic achievements than his ability to impersonate another tall, wealthy Massachusetts politician with good hair: Kerry served as Mitt Romney’s surrogate during weeks of preparation for the 2012 presidential debates.

Kerry channeled Romney so effectively that, aides to both men say, he got under Obama’s skin.

Kerry agreed that the U.S. should try to revive Middle East negotiations before the Palestinians again pushed for statehood, at the United Nations General Assembly in September 2013.

In private meetings with Israeli Prime Minister Netanyahu and Palestinian President Mahmoud Abbas, Obama pushed for a resumption of negotiations. At a final press conference before returning to Washington, Obama announced that he was handing the pursuit of talks over to Kerry.

“What I can guarantee is that Secretary Kerry is going to be spending a good deal of time in discussions with the parties.”

He met alone with Abbas for two hours in Amman and then flew to Jerusalem to meet with Netanyahu and three of his aides.

Kerry pressed on, returning in April to Jerusalem and Ramallah, the de facto Palestinian capital in the West Bank. After 24 hours of talks with both sides, Kerry held a press conference at the airport in Tel Aviv.

Kerry held three meetings with Netanyahu and Abbas in three days, including one meeting with the Israeli prime minister that lasted six hours, until 3 a.m. On June 29, he canceled a trip to the United Arab Emirates so he could keep talking with Netanyahu and Abbas, raising expectations of a breakthrough. On June 30, he held another press conference at the Tel Aviv airport.

“We started out with very wide gaps, and we have narrowed those considerably.”

Five months into the job, Kerry was off to an ominous start. His wife was in the hospital. Syria was convulsing. Progress toward Israeli-Palestinian talks was stalled. Egypt was burning. And Republican attack ads were making it appear as though the secretary of state had spent the weekend yachting.

Kerry said, according to the aide. “The only thing I’m interested in is a serious negotiation that can lead to a final-status agreement.”

“On behalf of President Obama, I am pleased to announce that we have reached an agreement that establishes a basis for resuming direct final-status negotiations between the Palestinians and the Israelis,” Kerry said, calmly and deliberately. “This is a significant and welcome step forward.” He declined to take questions.

Nine days later, the Israeli cabinet approved the release of the 104 Palestinian prisoners. The next day, Israeli and Palestinian officials arrived in Washington to begin peace talks.

The smallness of his circle of aides, which had been seen early on as a detriment to his management of the State Department, now made it easier to keep information contained.

Working with consultants from McKinsey, diplomats estimated that $4 billion in long-term private investment would flow to the Palestinians in the wake of an agreement.

Palestinian officials appear to have compromised on their demand for a settlement freeze.

From the beginning, Kerry had insisted that the Obama administration not allow a halt in Israeli settlement construction to become a public precondition.

Kerry also reiterated a core argument: the security that Israel currently enjoys is temporary, if not illusory. Without a two-state solution, Israel will face a European-led campaign of delegitimization, a new intifada, and a Palestinian leader far more radical than Abbas.

The crucial concession—the release of the 104 prisoners—came from the Israeli side

“It takes time to listen, it takes time to persuade,” Frank Lowenstein told me. “This is where Kerry’s willingness to stay up all night pays off.”

The U.S. provided nonlethal aid to the opposition, but White House officials were so fearful of American assistance inadvertently falling into the hands of jihadists that the National Security Council Deputies Committee monitored the distribution of the aid in granular detail. Qatar and Saudi Arabia, meanwhile, were funneling cash and weapons to hard-line militants, including Al Nusra Front, an al-Qaeda affiliate.

Russia continued providing Syria with arms and blocking any action by the UN Security Council.

When Putin finally received Kerry, after a three-hour delay, Putin reportedly fiddled continuously with his pen and “more resembled a man indulging a long-ago scheduled visit from the cultural attaché of Papua New Guinea than participating in an urgent summit with America’s top diplomat,”

At a late-night press conference, a beaming Kerry announced that he and Lavrov would co-host a peace conference in Geneva.

“They were great efforts, and again, I reiterate my gratitude to President Putin for a very generous welcome here.”

Earlier, in April, after American intelligence officials had confirmed that Assad had carried out several small-scale chemical-weapons attacks, Obama had reluctantly agreed to mount a covert CIA effort to arm and train moderate rebels.

if the United States did not “impose consequences” for Assad’s use of chemical weapons, the Syrian leader would see it as “a green light for continued CW use.” But the White House did not alter course.

Both Obama and Kerry favored a military response—air strikes—according to a senior administration official. As American intelligence agencies accumulated evidence suggesting that Assad was responsible, Kerry offered to make the public case for strikes. White House officials welcomed the idea and vetted his speeches.

“My vision is that, if you can make peace, if you can get Israel and Palestine resolved and can get the Iranian threat of a nuclear weapon put to bed appropriately—even if Syria didn’t calm down—if you get those two pieces or one piece of that, you’ve got a hugely changed dynamic in a region that is in turmoil. And if you take just the Palestinian-Israeli situation, you have the potential to make peace with 57 nations—35 Muslim nations and 22 Arab nations. If the issue is resolved, they will recognize Israel.”

Putin answered the man’s question in a long statement, insisting that the only path to regulating the crisis lay in the existing Minsk agreements between Moscow and Kiev.

Kashin said that ideally, for Russia, the disputed territory would gradually become a region on the Russian border similar to Transnistria in Moldova, which is under Moscow’s domination but not part of Russia.

And details like the graphite dust that blanketed everyone. (Graphite was used as a “moderator,” to slow down neutrons so they could split uranium atoms.)

“We found out how coal miners feel. After eight hours of machining graphite, we looked as if we were made up for a minstrel. One shower would remove only the surface graphite dust. About a half-hour after the first shower the dust in the pores of your skin would start oozing. Walking around the room where we cut graphite was like walking on a dance floor. Graphite is a dry lubricant, you know, and the cement floor covered with graphite dust was slippery.”

The Chicago Pile was a genuine scientific breakthrough, but other, more famous milestones like the Trinity test and the Hiroshima bombing have also been pegged as the beginning of the atomic age.

When the 25th anniversary came around in 1967, World War II was receding from memory and the Cold War had come startlingly close to turning hot. It was atomic weapons that Americans were thinking about again. Volney Wilson, another physicist who worked on the Chicago Pile, speaking to the Schenectady Gazette, was far less optimistic: “It’s been a big disappointment to me ... I would have thought that the development of this horrible weapon would have been more of a force to bring the world together.”

The 50th anniversary came at a more optimistic time: 1992. The Soviet Union had dissolved. The United States was the world’s only superpower. The Soviet Union was not only dismantling its warheads, it was selling them to the United States for electricity.

Which brings us to the75th anniversary of the Chicago Pile. Nuclear power is on the decline in the United States today. Nuclear weapons are ever present in the news again. Yet nuclear science has also produced real breakthroughs in science and medicine. The legacy of the Chicago Pile is mixed, and it probably always will be—until, and such is the nature of nuclear weapons, the day it is clearly not.

“Being vaccinated doesn’t mean you are immune. It means you have a better chance of protection.”

Immunity is not a monolith, and the degree of defense roused by an infection or a vaccine will differ from person to person, even between identical twins. Some people might have underlying conditions that hamstring their immune system’s response to vaccination; others might simply, by chance, churn out fewer or less potent antibodies and T cells that can nip a coronavirus infection in the bud.

An ideal response to vaccination might create an arsenal of immune molecules and cells that can instantaneously squelch the virus, leaving no time for symptoms to appear. But sometimes that front line of fighters is relatively sparse

Should the virus make it through, “it becomes a race [against] time,” Ellebedy told me. The pathogen rushes to copy itself, and the immune system recruits more defenders. The longer the tussle drags on, the more likely the disease is to manifest.

The range of vaccine responses “isn’t a variation of two- to threefold; it’s thousands,”

dislikes the term breakthrough case, which evokes a barrier walling humans off from disease. “It’s very misleading,” she told me. “It’s like the virus ‘punches’ through our defenses.”

The number of post-vaccination infections is also contingent on “the ongoing transmission situation,” Omer told me. “It depends on how much people are mixing.”

Vaccination is actually more like a single variable in a dynamic playing field—a layer of protection, like an umbrella, that might guard better in some situations than others. It could keep a lucky traveler relatively dry in a light drizzle, but in a windy maelstrom that’s whipping heavy droplets every which way, another person might be overwhelmed.

under many circumstances, vaccines are still best paired with safeguards such as masks and distancing—just as rain boots and jackets would help buffer someone in a storm.

Even excellent vaccines aren’t foolproof, and they shouldn’t be criticized when they’re not. “We can’t expect it’s going to be perfect, on day one, always,” Borio said.

The numbers for asymptomatic infections are still crystallizing, but they’re likely to be lower.

“Whenever someone tests positive, the real question is, are they sick, and how sick are they? That’s a big difference.”

Efficacy, a figure specific to clinical trials, also doesn’t always translate perfectly to the messiness of the real world, where there’s immense variability in how, when, where, by whom, and to whom shots are administered

The vaccine’s performance under these conditions is tracked by a separate measure, called effectiveness. Studies rigorously examining vaccine effectiveness are challenging, but early data suggest that the Pfizer-BioNTech and Moderna shots are living up to their initial hype.

he circumstances of exposure to any version of the coronavirus will also make a difference. If vaccinated people are spending time with groups of unvaccinated people in places where the virus is running rampant, that still raises their chance of getting sick. Large doses of the virus can overwhelm the sturdiest of immune defenses, if given the chance.

A vaccine with a recorded efficacy of 95 percent, for example, doesn’t give everyone who’s vaccinated a 5 percent chance of getting sick. Not all of those people will even encounter the virus

The key is how vaccination changes the outcome for those who are meaningfully exposed: Among 100 individuals who might have fallen ill without the vaccine, just five symptomatic cases might appear.

This artificial intelligence breakthrough, he argues, is being driven by cheap parallel computation technologies, big data collection and better algorithms. The upshot is clear, “The business plans of the next 10,000 start-ups are easy to forecast: Take X and add A.I.”

in 2001, the top 10 websites accounted for 31 percent of all U.S. page views, but, by 2010, they accounted for 75 percent of them.

The Internet has created a long tail, but almost all the revenue and power is among the small elite at the head.

Advances in artificial intelligence will accelerate this centralizing trend. That’s because A.I. companies will be able to reap the rewards of network effects. The bigger their network and the more data they collect, the more effective and attractive they become.

As a result, our A.I. future is likely to be ruled by an oligarchy of two or three large, general-purpose cloud-based commercial intelligences.”

engineers at a few gigantic companies will have vast-though-hidden power to shape how data are collected and framed, to harvest huge amounts of information, to build the frameworks through which the rest of us make decisions and to steer our choices. If you think this power will be used for entirely benign ends, then you have not read enough history.

The second implication is philosophical. A.I. will redefine what it means to be human. Our identity as humans is shaped by what machines and other animals can’t do

For the last few centuries, reason was seen as the ultimate human faculty. But now machines are better at many of the tasks we associate with thinking — like playing chess, winning at Jeopardy, and doing math.

On the other hand, machines cannot beat us at the things we do without conscious thinking: developing tastes and affections, mimicking each other and building emotional attachments, experiencing imaginative breakthroughs, forming moral sentiments.

In the age of smart machines, we’re not human because we have big brains. We’re human because we have social skills, emotional capacities and moral intuitions.

I could paint two divergent A.I. futures, one deeply humanistic, and one soullessly utilitarian.

In the humanistic one, machines liberate us from mental drudgery so we can focus on higher and happier things. In this future, differences in innate I.Q. are less important. Everybody has Google on their phones so having a great memory or the ability to calculate with big numbers doesn’t help as much.

In this future, there is increasing emphasis on personal and moral faculties: being likable, industrious, trustworthy and affectionate. People are evaluated more on these traits, which supplement machine thinking, and not the rote ones that duplicate it

In the cold, utilitarian future, on the other hand, people become less idiosyncratic. If the choice architecture behind many decisions is based on big data from vast crowds, everybody follows the prompts and chooses to be like each other. The machine prompts us to consume what is popular, the things that are easy and mentally undemanding.

That’s not to say that race relations in Europe are better than in the United States. As far as I am concerned, they are just as bad, if not worse, on average.

when I experienced racism in Eastern Europe, it was frequently harsh, even though I had the distinct advantage of being an American. Africans were treated far worse.

what I did enjoy about Eastern Europe, especially Ukraine, was that I was able to make many breakthroughs on race with locals that I have yet to experience in the United States. Instead of entrenching in their racial ignorance, Ukrainians were honest about their naiveté and open to learning about a different culture.

"One lesson from this is that you can do a deal with the North Koreans, and you can get substantial value out of a deal, which we did for about a decade," Gallucci said. "But you can also expect, from our perspective at least, that they will cheat on the deal."

Total funding for clean-tech start-ups fell during most of the past decade

But there are dozens, if not hundreds, of start-ups developing new technologies that address the issue.

Two major scientific organizations said last fall that even if greenhouse-gas emissions were reduced significantly, stopping drastic global warming would require technological breakthroughs that allowed for the removal of billions of tons of carbon dioxide already in the atmosphere.

Some promising methods for accomplishing that involve old-fashioned technologies, like planting trees and changing the ways farmers till their fields

In 2018, $6.6 billion was invested in clean tech, about 15 percent of what went to software start-ups. Carbon-removal start-ups got a tiny sliver of that.

So far, no one has found an obvious way to turn capturing carbon dioxide into a profitable business.

Noah Deich, the founder of Carbon180, a nonprofit that sponsored the event, said it was encouraging to see investors there. But he said he had not seen the commitment to investing that he believed was necessary to get the technologies working.

“For an internet company, even if you don’t have a real product, you can get money to develop one,” he said. “Here, it’s the opposite.

“It is tackling big markets and big challenges, but that doesn’t necessarily mean that those are going to be big businesses,”

a broad array of investors, including venture capitalists, will need to get involved. And they will need to wait more than three or four years to cash out

Mr. Oros said that his fund had not made an investment in the sector and that he did not see a way for the industry to take off without government policy encouraging it

for these businesses to succeed it would probably be necessary for governments to create a carbon tax or other subsidies as incentives for new businesses.

Mr. Lackner said investors should assume that governments would be willing at some point to pay for what these companies were doing.

“In the end, there is no way for the market to not exist,” he said. “This will be a brand-new industry at a huge scale.”

In the time it took Carbon Engineering to raise one round of $68 million, Slack, a messaging company founded the same year, has raised more than 10 times as much and is now preparing for an initial public offering that could value it at nearly $20 billion.

Everyone who discusses the difficulties these start-ups face points back to the clean-tech boom, when several venture capital firms put billions of dollars into solar energy and other technologies. While solar power has gained traction, most of the clean-tech funds were viewed as failures.

venture capitalists needed their investments to show returns within a few years

“There is a fundamental mismatch in time lines,”

One of the biggest investors in climate-focused start-ups is Breakthrough Energy Ventures, a $1 billion fund that seeks to support the development of world-saving technology that might not have a quick turnaround. The fund has received money from Bill Gates and several other billionaires.

money from major philanthropists would not be enough to get even one start-up up to speed, much less the dozens needed to meet the carbon-reduction goals set by international bodies like the Intergovernmental Panel on Climate Change

Ocean-Based Climate Solutions, has created a device that stirs up water in the ocean to promote the growth of phytoplankton, which are algae that can take carbon dioxide out of the air and deliver it to the bottom of the sea in solid form.

“We don’t need another photo-sharing app or another blockchain start-up,” said Mr. Rogers, who is investing his money through Incite Ventures, a fund he created with his wife, Swati Mylavarapu. “We need to solve the carbon crisis. But a lot of folks are chasing the easy money rather than taking responsibility for what needs to be done.”

Science has explained the problem: Certain gases in the atmosphere trap heat at the Earth’s surface. More of those gases in the atmosphere will trap more heat, unleashing a cascade of unpredictable effects.

As always with science, the unlocked knowledge reveals more mysteries to be plumbed. How will Earth’s complex climate react, and how quickly? And how will Earth’s most creative and adaptable species, human beings, react to shape the outcome?

The challenge of climate change demands an urgent response but not an apocalyptic one

For example: It has become common in certain circles for people to say they won’t have children because of the impending hellscape of drought, fire, flood and tempest that will ruin future lives. How common? A celebrity member of Congress gave an endorsement

“Basically, there’s a scientific consensus that the lives of children are going to be very difficult,” said Rep. Alexandria Ocasio-Cortez (D-N.Y.). She added: “And it does lead, I think, young people to have a legitimate question: Is it okay to still have children?

This is not the language of science. That gloomy “consensus” has no scientific claim

Instead, with so much still to be learned and such a powerful tool in science, optimism is the attitude worthy of the work ahead.

We scoff at the ignorance of our elders who searched comets for portents of The End. But how different are we?

what happens when an extraordinarily rich society can’t find enough new ideas that justify investing all its stockpiled wealth. We inflate bubbles and then pop them, invest in Theranos and then repent, and the supposed cutting edge of capitalism is increasingly defined by technologies that have almost arrived, business models that are on their way to profitability, by runways that go on and on without the plane achieving takeoff.

what this tells us, unfortunately, is that 21st-century growth and innovation are not at all that we were promised they would be.

slowly compounding growth is not the same as dynamism. American entrepreneurship has been declining since the 1970s: Early in the Jimmy Carter presidency, 17 percent of all United States businesses had been founded in the previous year; by the start of Barack Obama’s second term, that rate was about 10 percent. In the late 1980s, almost half of United States companies were “young,” meaning less than five years old; by the Great Recession, that share was down to only 39 percent, and the share of “old” firms (founded more than 15 years ago) rose from 22 percent to 34 percent over a similar period

From World War II through the 1980s, according to a recent report from Senator Marco Rubio’s office, private domestic investment often approached 10 percent of G.D.P.; in 2019, despite a corporate tax cut intended to get money off the sidelines, the investment-to-G.D.P. ratio was less than half of that.

This suggests that the people with the most experience starting businesses look around at their investment opportunities and see many more start-ups that resemble Theranos than resemble Amazon, let alone the behemoths of the old economy.

the dearth of corporate investment also means that the steady climb of the stock market has boosted the wealth of a rentier class — basically, already-rich investors getting richer off dividends — rather than reflecting surging prosperity in general.

In 2017 a group of economists published a paper asking, “Are Ideas Getting Harder to Find?” The answer was a clear yes: “We present a wide range of evidence from various industries, products, and firms showing that research effort is rising substantially while research productivity is declining sharply.”

In his 2011 book “The Great Stagnation,” Tyler Cowen cited an analysis from the Pentagon physicist Jonathan Huebner, who modeled an innovations-to-population ratio for the last 600 years: It shows a slowly ascending arc through the late 19th century, when major inventions were rather easy to conceive and adopt, and a steepening decline ever since, as rich countries spend more and more on research to diminishing returns.

the trends reveal a slowdown, a mounting difficulty in achieving breakthroughs — a bottleneck if you’re optimistic, a ceiling if you aren’t

the relative exception, the internet and all its wonders, highlights the general pattern.

The Northwestern University economist Robert Gordon, one of the most persuasive theorists of stagnation, points out that the period from 1840 to 1970 featured dramatic growth and innovation across multiple arenas — energy and transportation and medicine and agriculture and communication and the built environment.

in the last two generations, progress has become increasingly monodimensional — all tech and nothing else.

We used to travel faster, build bigger, live longer; now we communicate faster, chatter more, snap more selfies.

Take a single one of the great breakthroughs of the industrial age — planes and trains and automobiles, antibiotics and indoor plumbing — and it still looms larger in our everyday existence than all of the contributions of the tech revolution combined.

With this stagnation comes social torpor. America is a more peaceable country than it was in 1970 or 1990, with lower crime rates and safer streets and better-behaved kids

it’s also a country where that supposedly most American of qualities, wanderlust, has markedly declined: Americans no longer “go west” (or east or north or south) in search of opportunity the way they did 50 years ago; the rate at which people move between states has fallen from 3.5 percent in the early 1970s to 1.4 percent in 2010. Nor do Americans change jobs as often as they once did.

Meanwhile, those well-behaved young people are more depressed than prior cohorts, less likely to drive drunk or get pregnant but more tempted toward self-harm

once we crossed over into permanent below-replacement territory, the birth dearth began undercutting the very forces (youth, risk -taking, dynamism) necessary for continued growth, meaning that any further gains to individual welfare are coming at the future’s expense.

then there is the opioid epidemic, whose spread across the unhappiest parts of white America passed almost unnoticed in elite circles for a while because the drug itself quiets rather than inflames, supplying a gentle euphoria that lets its users simply slip away, day by day and bit by bit, without causing anyone any trouble

In the land of the lotus eaters, people are also less likely to invest in the future in the most literal of ways. The United States birthrate was once an outlier among developed countries, but since the Great Recession, it has descended rapidly, converging with the wealthy world’s general below-replacement norm.

This demographic decline worsens economic stagnation; economists reckoning with its impact keep finding stark effects. A 2016 analysis found that a 10 percent increase in the fraction of the population over 60 decreased the growth rate of states’ per capita G.D.P. by 5.5 percent.

This doesn’t excuse the grifting or the rage stoking, especially presidential grifting and rage stoking, and it doesn’t make the mass shootings, when they come, any less horrific. But it’s important context for thinking about whether online politics is really carrying our society downward into civil strife

This feedback loop — in which sterility feeds stagnation, which further discourages childbearing, which sinks society ever-deeper into old age — makes demographic decline a clear example of how decadence overtakes a civilization

Both populism and socialism, Trump and Bernie Sanders, represent expressions of discontent with decadence, rebellions against the technocratic management of stagnation that defined the Obama era.

in practical terms the populist era has mostly delivered a new and deeper stalemate. From Trump’s Washington to the capitals of Europe, Western politics is now polarized between anti-establishment forces that are unprepared to competently govern and an establishment that’s too disliked to effectively rule.

The hysteria with which we’re experiencing them may represent nothing more than the way that a decadent society manages its political passions, by encouraging people to playact extremism, to re-enact the 1930s or 1968 on social media, to approach radical politics as a sport, a hobby, a kick to the body chemistry, that doesn’t put anything in their relatively comfortable late-modern lives at risk.

The terrorist in 21st-century America isn’t the guy who sees more deeply than the rest; he’s the guy who doesn’t get it, who takes the stuff he reads on the internet literally in a way that most of the people posting don’t

For adults, the increasingly legal drug of choice is marijuana, whose prototypical user is a relaxed and harmless figure — comfortably numb, experiencing stagnation as a chill good time.

It suggests that the virtual realm might make our battles more ferocious but also more performative and empty; and that online rage is a steam-venting technology for a society that is misgoverned, stagnant and yet, ultimately, far more stable than it looks on Twitter

in the real world, it’s possible that Western society is leaning back in an easy chair, hooked up to a drip of something soothing, playing and replaying an ideological greatest-hits tape from its wild and crazy youth.

Human beings can still live vigorously amid a general stagnation, be fruitful amid sterility, be creative amid repetition. And the decadent society, unlike the full dystopia, allows those signs of contradictions to exist

The last hundred-odd years of Western history offer plenty of examples of how the attempt to throw off decadence can bring in far worse evils, from the craving for Meaning and Action that piled corpses at Verdun and Passchendaele, to the nostalgic yearning for the Cold War that inspired post-9/11 crusading and led to a military quagmire in the Middle East.

So you can even build a case for decadence, not as a falling-off or disappointing end, but as a healthy balance between the misery of poverty and the dangers of growth for growth’s sake

A sustainable decadence, if you will, in which the crucial task for 21st-century humanity would be making the most of a prosperous stagnation: learning to temper our expectations and live within limits; making sure existing resources are distributed more justly; using education to lift people into the sunlit uplands of the creative class; and doing everything we can to help poorer countries transition successfully into our current position

this argument carries you only so far. Even if the dystopia never quite arrives, the longer a period of stagnation continues, the narrower the space for fecundity and piety, memory and invention, creativity and daring.

So decadence must be critiqued and resisted

by the hope that where there’s stability, there also might eventually be renewal,

The next renaissance will be necessarily different, but realism about our own situation should make us more inclined, not less, to look and hope for one — for the day when our culture feels more fruitful, our politics less futile and the frontiers that seem closed today are opened once again.

If the world had adopted the proposal widely endorsed at the end of the ’80s — a freezing of carbon emissions, with a reduction of 20 percent by 2005 — warming could have been held to less than 1.5 degrees.

Action had to be taken, and the United States would need to lead. It didn’t.

There can be no understanding of our current and future predicament without understanding why we failed to solve this problem when we had the chance.

The first suggestion to Rafe Pomerance that humankind was destroying the conditions necessary for its own survival came on Page 66 of the government publication EPA-600/7-78-019. It was a technical report about coal

‘This Is the Whole Banana’ Spring 1979

here was an urgent problem that demanded their attention, MacDonald believed, because human civilization faced an existential crisis. In “How to Wreck the Environment,” a 1968 essay published while he was a science adviser to Lyndon Johnson, MacDonald predicted a near future in which “nuclear weapons were effectively banned and the weapons of mass destruction were those of environmental catastrophe.” One of the most potentially devastating such weapons, he believed, was the gas that we exhaled with every breath: carbon dioxide. By vastly increasing carbon emissions, the world’s most advanced militaries could alter weather patterns and wreak famine, drought and economic collapse.

the Jasons. They were like one of those teams of superheroes with complementary powers that join forces in times of galactic crisis. They had been brought together by federal agencies, including the C.I.A, to devise scientific solutions to national-security problems: how to detect an incoming missile; how to predict fallout from a nuclear bomb; how to develop unconventional weapons, like plague-infested rats.

Agle pointed to an article about a prominent geophysicist named Gordon MacDonald, who was conducting a study on climate change with the Jasons, the mysterious coterie of elite scientists to which he belonged

During the spring of 1977 and the summer of 1978, the Jasons met to determine what would happen once the concentration of carbon dioxide in the atmosphere doubled from pre-Industrial Revolution levels. It was an arbitrary milestone, the doubling, but a useful one, as its inevitability was not in question; the threshold would most likely be breached by 2035.

The Jasons’ report to the Department of Energy, “The Long-Term Impact of Atmospheric Carbon Dioxide on Climate,” was written in an understated tone that only enhanced its nightmarish findings: Global temperatures would increase by an average of two to three degrees Celsius; Dust Bowl conditions would “threaten large areas of North America, Asia and Africa”; access to drinking water and agricultural production would fall, triggering mass migration on an unprecedented scale. “Perhaps the most ominous feature,” however, was the effect of a changing climate on the poles. Even a minimal warming “could lead to rapid melting” of the West Antarctic ice sheet. The ice sheet contained enough water to raise the level of the oceans 16 feet.

MacDonald explained that he first studied the carbon-dioxide issue when he was about Pomerance’s age — in 1961, when he served as an adviser to John F. Kennedy. Pomerance pieced together that MacDonald, in his youth, had been something of a prodigy: In his 20s, he advised Dwight D. Eisenhower on space exploration; at 32, he became a member of the National Academy of Sciences; at 40, he was appointed to the inaugural Council on Environmental Quality, where he advised Richard Nixon on the environmental dangers of burning coal. He monitored the carbon-dioxide problem the whole time, with increasing alarm.

They were surprised to learn how few senior officials were familiar with the Jasons’ findings, let alone understood the ramifications of global warming. At last, having worked their way up the federal hierarchy, the two went to see the president’s top scientist, Frank Press.

Thus began the Gordon and Rafe carbon-dioxide roadshow. Beginning in the spring of 1979, Pomerance arranged informal briefings with the E.P.A., the National Security Council, The New York Times, the Council on Environmental Quality and the Energy Department, which, Pomerance learned, had established an Office of Carbon Dioxide Effects two years earlier at MacDonald’s urging

. Out of respect for MacDonald, Press had summoned to their meeting what seemed to be the entire senior staff of the president’s Office of Science and Technology Policy — the officials consulted on every critical matter of energy and national security. What Pomerance had expected to be yet another casual briefing assumed the character of a high-level national-security meeting.

MacDonald would begin his presentation by going back more than a century to John Tyndall — an Irish physicist who was an early champion of Charles Darwin’s work and died after being accidentally poisoned by his wife. In 1859, Tyndall found that carbon dioxide absorbed heat and that variations in the composition of the atmosphere could create changes in climate. These findings inspired Svante Arrhenius, a Swedish chemist and future Nobel laureate, to deduce in 1896 that the combustion of coal and petroleum could raise global temperatures. This warming would become noticeable in a few centuries, Arrhenius calculated, or sooner if consumption of fossil fuels continued to increase.

Four decades later, a British steam engineer named Guy Stewart Callendar discovered that, at the weather stations he observed, the previous five years were the hottest in recorded history. Humankind, he wrote in a paper, had become “able to speed up the processes of Nature.” That was in 1939.

MacDonald’s history concluded with Roger Revelle, perhaps the most distinguished of the priestly caste of government scientists who, since the Manhattan Project, advised every president on major policy; he had been a close colleague of MacDonald and Press since they served together under Kennedy. In a 1957 paper written with Hans Suess, Revelle concluded that “human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.” Revelle helped the Weather Bureau establish a continuous measurement of atmospheric carbon dioxide at a site perched near the summit of Mauna Loa on the Big Island of Hawaii, 11,500 feet above the sea — a rare pristine natural laboratory on a planet blanketed by fossil-fuel emissions.

After nearly a decade of observation, Revelle had shared his concerns with Lyndon Johnson, who included them in a special message to Congress two weeks after his inauguration. Johnson explained that his generation had “altered the composition of the atmosphere on a global scale” through the burning of fossil fuels, and his administration commissioned a study of the subject by his Science Advisory Committee. Revelle was its chairman, and its 1965 executive report on carbon dioxide warned of the rapid melting of Antarctica, rising seas, increased acidity of fresh waters — changes that would require no less than a coordinated global effort to forestall.Yet emissions continued to rise, and at this rate, MacDonald warned, they could see a snowless New England, the swamping of major coastal cities, as much as a 40 percent decline in national wheat production, the forced migration of about one-quarter of the world’s population. Not within centuries — within their own lifetimes.

On May 22, Press wrote a letter to the president of the National Academy of Sciences requesting a full assessment of the carbon-dioxide issue. Jule Charney, the father of modern meteorology, would gather the nation’s top oceanographers, atmospheric scientists and climate modelers to judge whether MacDonald’s alarm was justified — whether the world was, in fact, headed to cataclysm.

If Charney’s group confirmed that the world was careering toward an existential crisis, the president would be forced to act.

Hansen turned from the moon to Venus. Why, he tried to determine, was its surface so hot? In 1967, a Soviet satellite beamed back the answer: The planet’s atmosphere was mainly carbon dioxide. Though once it may have had habitable temperatures, it was believed to have succumbed to a runaway greenhouse effect: As the sun grew brighter, Venus’s ocean began to evaporate, thickening the atmosphere, which forced yet greater evaporation — a self-perpetuating cycle that finally boiled off the ocean entirely and heated the planet’s surface to more than 800 degrees Fahrenheit

At the other extreme, Mars’s thin atmosphere had insufficient carbon dioxide to trap much heat at all, leaving it about 900 degrees colder. Earth lay in the middle, its Goldilocks greenhouse effect just strong enough to support life.

We want to learn more about Earth’s climate, Jim told Anniek — and how humanity can influence it. He would use giant new supercomputers to map the planet’s atmosphere. They would create Mirror Worlds: parallel realities that mimicked our own. These digital simulacra, technically called “general circulation models,” combined the mathematical formulas that governed the behavior of the sea, land and sky into a single computer model. Unlike the real world, they could be sped forward to reveal the future.

The government officials, many of them scientists themselves, tried to suppress their awe of the legends in their presence: Henry Stommel, the world’s leading oceanographer; his protégé, Carl Wunsch, a Jason; the Manhattan Project alumnus Cecil Leith; the Harvard planetary physicist Richard Goody. These were the men who, in the last three decades, had discovered foundational principles underlying the relationships among sun, atmosphere, land and ocean — which is to say, the climate.

When, at Charney’s request, Hansen programmed his model to consider a future of doubled carbon dioxide, it predicted a temperature increase of four degrees Celsius. That was twice as much warming as the prediction made by the most prominent climate modeler, Syukuro Manabe, whose government lab at Princeton was the first to model the greenhouse effect. The difference between the two predictions — between warming of two degrees Celsius and four degrees Celsius — was the difference between damaged coral reefs and no reefs whatsoever, between thinning forests and forests enveloped by desert, between catastrophe and chaos.

The discrepancy between the models, Arakawa concluded, came down to ice and snow. The whiteness of the world’s snowfields reflected light; if snow melted in a warmer climate, less radiation would escape the atmosphere, leading to even greater warming. Shortly before dawn, Arakawa concluded that Manabe had given too little weight to the influence of melting sea ice, while Hansen had overemphasized it. The best estimate lay in between. Which meant that the Jasons’ calculation was too optimistic. When carbon dioxide doubled in 2035 or thereabouts, global temperatures would increase between 1.5 and 4.5 degrees Celsius, with the most likely outcome a warming of three degrees.

within the highest levels of the federal government, the scientific community and the oil-and-gas industry — within the commonwealth of people who had begun to concern themselves with the future habitability of the planet — the Charney report would come to have the authority of settled fact. It was the summation of all the predictions that had come before, and it would withstand the scrutiny of the decades that followed it. Charney’s group had considered everything known about ocean, sun, sea, air and fossil fuels and had distilled it to a single number: three. When the doubling threshold was broached, as appeared inevitable, the world would warm three degrees Celsius

The last time the world was three degrees warmer was during the Pliocene, three million years ago, when beech trees grew in Antarctica, the seas were 80 feet higher and horses galloped across the Canadian coast of the Arctic Ocean.

After the publication of the Charney report, Exxon decided to create its own dedicated carbon-dioxide research program, with an annual budget of $600,000. Only Exxon was asking a slightly different question than Jule Charney. Exxon didn’t concern itself primarily with how much the world would warm. It wanted to know how much of the warming Exxon could be blamed for.

“It behooves us to start a very aggressive defensive program,” Shaw wrote in a memo to a manager, “because there is a good probability that legislation affecting our business will be passed.”

Shaw turned to Wallace Broecker, a Columbia University oceanographer who was the second author of Roger Revelle’s 1965 carbon-dioxide report for Lyndon Johnson. In 1977, in a presentation at the American Geophysical Union, Broecker predicted that fossil fuels would have to be restricted, whether by taxation or fiat. More recently, he had testified before Congress, calling carbon dioxide “the No.1 long-term environmental problem.” If presidents and senators trusted Broecker to tell them the bad news, he was good enough for Exxon.

The company had been studying the carbon-dioxide problem for decades, since before it changed its name to Exxon. In 1957, scientists from Humble Oil published a study tracking “the enormous quantity of carbon dioxide” contributed to the atmosphere since the Industrial Revolution “from the combustion of fossil fuels.” Even then, the observation that burning fossil fuels had increased the concentration of carbon in the atmosphere was well understood and accepted by Humble’s scientists.

The American Petroleum Institute, the industry’s largest trade association, asked the same question in 1958 through its air-pollution study group and replicated the findings made by Humble Oil. So did another A.P.I. study conducted by the Stanford Research Institute a decade later, in 1968, which concluded that the burning of fossil fuels would bring “significant temperature changes” by the year 2000 and ultimately “serious worldwide environmental changes,” including the melting of the Antarctic ice cap and rising seas.

The ritual repeated itself every few years. Industry scientists, at the behest of their corporate bosses, reviewed the problem and found good reasons for alarm and better excuses to do nothing. Why should they act when almost nobody within the United States government — nor, for that matter, within the environmental movement — seemed worried?

Why take on an intractable problem that would not be detected until this generation of employees was safely retired? Worse, the solutions seemed more punitive than the problem itself. Historically, energy use had correlated to economic growth — the more fossil fuels we burned, the better our lives became. Why mess with that?

That June, Jimmy Carter signed the Energy Security Act of 1980, which directed the National Academy of Sciences to start a multiyear, comprehensive study, to be called “Changing Climate,” that would analyze social and economic effects of climate change. More urgent, the National Commission on Air Quality, at the request of Congress, invited two dozen experts, including Henry Shaw himself, to a meeting in Florida to propose climate policy.

On April 3, 1980, Senator Paul Tsongas, a Massachusetts Democrat, held the first congressional hearing on carbon-dioxide buildup in the atmosphere. Gordon MacDonald testified that the United States should “take the initiative” and develop, through the United Nations, a way to coordinate every nation’s energy policies to address the problem.

During the expansion of the Clean Air Act, he pushed for the creation of the National Commission on Air Quality, charged with ensuring that the goals of the act were being met. One such goal was a stable global climate. The Charney report had made clear that goal was not being met, and now the commission wanted to hear proposals for legislation. It was a profound responsibility, and the two dozen experts invited to the Pink Palace — policy gurus, deep thinkers, an industry scientist and an environmental activist — had only three days to achieve it, but the utopian setting made everything seem possible

We have less time than we realize, said an M.I.T. nuclear engineer named David Rose, who studied how civilizations responded to large technological crises. “People leave their problems until the 11th hour, the 59th minute,” he said. “And then: ‘Eloi, Eloi, Lama Sabachthani?’ ” — “My God, my God, why hast thou forsaken me?”

The attendees seemed to share a sincere interest in finding solutions. They agreed that some kind of international treaty would ultimately be needed to keep atmospheric carbon dioxide at a safe level. But nobody could agree on what that level was.

William Elliott, a NOAA scientist, introduced some hard facts: If the United States stopped burning carbon that year, it would delay the arrival of the doubling threshold by only five years. If Western nations somehow managed to stabilize emissions, it would forestall the inevitable by only eight years. The only way to avoid the worst was to stop burning coal. Yet China, the Soviet Union and the United States, by far the world’s three largest coal producers, were frantically accelerating extraction.

“Do we have a problem?” asked Anthony Scoville, a congressional science consultant. “We do, but it is not the atmospheric problem. It is the political problem.” He doubted that any scientific report, no matter how ominous its predictions, would persuade politicians to act.

The talk of ending oil production stirred for the first time the gentleman from Exxon. “I think there is a transition period,” Henry Shaw said. “We are not going to stop burning fossil fuels and start looking toward solar or nuclear fusion and so on. We are going to have a very orderly transition from fossil fuels to renewable energy sources.”

What if the problem was that they were thinking of it as a problem? “What I am saying,” Scoville continued, “is that in a sense we are making a transition not only in energy but the economy as a whole.” Even if the coal and oil industries collapsed, renewable technologies like solar energy would take their place. Jimmy Carter was planning to invest $80 billion in synthetic fuel. “My God,” Scoville said, “with $80 billion, you could have a photovoltaics industry going that would obviate the need for synfuels forever!”

nobody could agree what to do. John Perry, a meteorologist who had worked as a staff member on the Charney report, suggested that American energy policy merely “take into account” the risks of global warming, though he acknowledged that a nonbinding measure might seem “intolerably stodgy.” “It is so weak,” Pomerance said, the air seeping out of him, “as to not get us anywhere.”

Scoville pointed out that the United States was responsible for the largest share of global carbon emissions. But not for long. “If we’re going to exercise leadership,” he said, “the opportunity is now.

One way to lead, he proposed, would be to classify carbon dioxide as a pollutant under the Clean Air Act and regulate it as such. This was received by the room like a belch. By Scoville’s logic, every sigh was an act of pollution. Did the science really support such an extreme measure? The Charney report did exactly that, Pomerance said.

Slade, the director of the Energy Department’s carbon-dioxide program, considered the lag a saving grace. If changes did not occur for a decade or more, he said, those in the room couldn’t be blamed for failing to prevent them. So what was the problem?

“Call it whatever.” Besides, Pomerance added, they didn’t have to ban coal tomorrow. A pair of modest steps could be taken immediately to show the world that the United States was serious: the implementation of a carbon tax and increased investment in renewable energy. Then the United States could organize an international summit meeting to address climate change

these two dozen experts, who agreed on the major points and had made a commitment to Congress, could not draft a single paragraph. Hours passed in a hell of fruitless negotiation, self-defeating proposals and impulsive speechifying. Pomerance and Scoville pushed to include a statement calling for the United States to “sharply accelerate international dialogue,” but they were sunk by objections and caveats.

They never got to policy proposals. They never got to the second paragraph. The final statement was signed by only the moderator, who phrased it more weakly than the declaration calling for the workshop in the first place. “The guide I would suggest,” Jorling wrote, “is whether we know enough not to recommend changes in existing policy.”

Pomerance had seen enough. A consensus-based strategy would not work — could not work — without American leadership. And the United States wouldn’t act unless a strong leader persuaded it to do so — someone who would speak with authority about the science, demand action from those in power and risk everything in pursuit of justice.

The meeting ended Friday morning. On Tuesday, four days later, Ronald Reagan was elected president.

‘Otherwise, They’ll Gurgle’ November 1980-September 1981

In the midst of this carnage, the Council on Environmental Quality submitted a report to the White House warning that fossil fuels could “permanently and disastrously” alter Earth’s atmosphere, leading to “a warming of the Earth, possibly with very serious effects.” Reagan did not act on the council’s advice. Instead, his administration considered eliminating the council.

After the election, Reagan considered plans to close the Energy Department, increase coal production on federal land and deregulate surface coal mining. Once in office, he appointed James Watt, the president of a legal firm that fought to open public lands to mining and drilling, to run the Interior Department. “We’re deliriously happy,” the president of the National Coal Association was reported to have said. Reagan preserved the E.P.A. but named as its administrator Anne Gorsuch, an anti-regulation zealot who proceeded to cut the agency’s staff and budget by about a quarter

Reagan “has declared open war on solar energy,” the director of the nation’s lead solar-energy research agency said, after he was asked to resign). Reagan appeared determined to reverse the environmental achievements of Jimmy Carter, before undoing those of Richard Nixon, Lyndon Johnson, John F. Kennedy and, if he could get away with it, Theodore Roosevelt.

When Reagan considered closing the Council on Environmental Quality, its acting chairman, Malcolm Forbes Baldwin, wrote to the vice president and the White House chief of staff begging them to reconsider; in a major speech the same week, “A Conservative’s Program for the Environment,” Baldwin argued that it was “time for today’s conservatives explicitly to embrace environmentalism.” Environmental protection was not only good sense. It was good business. What could be more conservative than an efficient use of resources that led to fewer federal subsidies?

Meanwhile the Charney report continued to vibrate at the periphery of public consciousness. Its conclusions were confirmed by major studies from the Aspen Institute, the International Institute for Applied Systems Analysis near Vienna and the American Association for the Advancement of Science. Every month or so, nationally syndicated articles appeared summoning apocalypse: “Another Warning on ‘Greenhouse Effect,’ ” “Global Warming Trend ‘Beyond Human Experience,’ ” “Warming Trend Could ‘Pit Nation Against Nation.’

Pomerance read on the front page of The New York Times on Aug. 22, 1981, about a forthcoming paper in Science by a team of seven NASA scientists. They had found that the world had already warmed in the past century. Temperatures hadn’t increased beyond the range of historical averages, but the scientists predicted that the warming signal would emerge from the noise of routine weather fluctuations much sooner than previously expected. Most unusual of all, the paper ended with a policy recommendation: In the coming decades, the authors wrote, humankind should develop alternative sources of energy and use fossil fuels only “as necessary.” The lead author was James Hansen.

Pomerance listened and watched. He understood Hansen’s basic findings well enough: Earth had been warming since 1880, and the warming would reach “almost unprecedented magnitude” in the next century, leading to the familiar suite of terrors, including the flooding of a 10th of New Jersey and a quarter of Louisiana and Florida. But Pomerance was excited to find that Hansen could translate the complexities of atmospheric science into plain English.

7. ‘We’re All Going to Be the Victims’ March 1982

Gore had learned about climate change a dozen years earlier as an undergraduate at Harvard, when he took a class taught by Roger Revelle. Humankind was on the brink of radically transforming the global atmosphere, Revelle explained, drawing Keeling’s rising zigzag on the blackboard, and risked bringing about the collapse of civilization. Gore was stunned: Why wasn’t anyone talking about this?

Most in Congress considered the science committee a legislative backwater, if they considered it at all; this made Gore’s subcommittee, which had no legislative authority, an afterthought to an afterthought. That, Gore vowed, would change. Environmental and health stories had all the elements of narrative drama: villains, victims and heroes. In a hearing, you could summon all three, with the chairman serving as narrator, chorus and moral authority. He told his staff director that he wanted to hold a hearing every week.

The Revelle hearing went as Grumbly had predicted. The urgency of the issue was lost on Gore’s older colleagues, who drifted in and out while the witnesses testified. There were few people left by the time the Brookings Institution economist Lester Lave warned that humankind’s profligate exploitation of fossil fuels posed an existential test to human nature. “Carbon dioxide stands as a symbol now of our willingness to confront the future,” he said. “It will be a sad day when we decide that we just don’t have the time or thoughtfulness to address those issues.”

That night, the news programs featured the resolution of the baseball strike, the ongoing budgetary debate and the national surplus of butter.

There emerged, despite the general comity, a partisan divide. Unlike the Democrats, the Republicans demanded action. “Today I have a sense of déjà vu,” said Robert Walker, a Republican from Pennsylvania. In each of the last five years, he said, “we have been told and told and told that there is a problem with the increasing carbon dioxide in the atmosphere. We all accept that fact, and we realize that the potential consequences are certainly major in their impact on mankind.” Yet they had failed to propose a single law. “Now is the time,” he said. “The research is clear. It is up to us now to summon the political will.”

Hansen flew to Washington to testify on March 25, 1982, performing before a gallery even more thinly populated than at Gore’s first hearing on the greenhouse effect. Gore began by attacking the Reagan administration for cutting funding for carbon-dioxide research despite the “broad consensus in the scientific community that the greenhouse effect is a reality.” William Carney, a Republican from New York, bemoaned the burning of fossil fuels and argued passionately that science should serve as the basis for legislative policy

the experts invited by Gore agreed with the Republicans: The science was certain enough. Melvin Calvin, a Berkeley chemist who won the Nobel Prize for his work on the carbon cycle, said that it was useless to wait for stronger evidence of warming. “You cannot do a thing about it when the signals are so big that they come out of the noise,” he said. “You have to look for early warning signs.”

Hansen’s job was to share the warning signs, to translate the data into plain English. He explained a few discoveries that his team had made — not with computer models but in libraries. By analyzing records from hundreds of weather stations, he found that the surface temperature of the planet had already increased four-tenths of a degree Celsius in the previous century. Data from several hundred tide-gauge stations showed that the oceans had risen four inches since the 1880s

It occurred to Hansen that this was the only political question that mattered: How long until the worst began? It was not a question on which geophysicists expended much effort; the difference between five years and 50 years in the future was meaningless in geologic time. Politicians were capable of thinking only in terms of electoral time: six years, four years, two years. But when it came to the carbon problem, the two time schemes were converging.

“Within 10 or 20 years,” Hansen said, “we will see climate changes which are clearly larger than the natural variability.” James Scheuer wanted to make sure he understood this correctly. No one else had predicted that the signal would emerge that quickly. “If it were one or two degrees per century,” he said, “that would be within the range of human adaptability. But we are pushing beyond the range of human adaptability.” “Yes,” Hansen said.

How soon, Scheuer asked, would they have to change the national model of energy production? Hansen hesitated — it wasn’t a scientific question. But he couldn’t help himself. He had been irritated, during the hearing, by all the ludicrous talk about the possibility of growing more trees to offset emissions. False hopes were worse than no hope at all: They undermined the prospect of developing real solutions. “That time is very soon,” Hansen said finally. “My opinion is that it is past,” Calvin said, but he was not heard because he spoke from his seat. He was told to speak into the microphone. “It is already later,” Calvin said, “than you think.”

From Gore’s perspective, the hearing was an unequivocal success. That night Dan Rather devoted three minutes of “CBS Evening News” to the greenhouse effect. A correspondent explained that temperatures had increased over the previous century, great sheets of pack ice in Antarctica were rapidly melting, the seas were rising; Calvin said that “the trend is all in the direction of an impending catastrophe”; and Gore mocked Reagan for his shortsightedness. Later, Gore could take credit for protecting the Energy Department’s carbon-dioxide program, which in the end was largely preserved.

8. ‘The Direction of an Impending Catastrophe’ 1982

Following Henry Shaw’s recommendation to establish credibility ahead of any future legislative battles, Exxon had begun to spend conspicuously on global-warming research. It donated tens of thousands of dollars to some of the most prominent research efforts, including one at Woods Hole led by the ecologist George Woodwell, who had been calling for major climate policy as early as the mid-1970s, and an international effort coordinated by the United Nations. Now Shaw offered to fund the October 1982 symposium on climate change at Columbia’s Lamont-Doherty campus.

David boasted that Exxon would usher in a new global energy system to save the planet from the ravages of climate change. He went so far as to argue that capitalism’s blind faith in the wisdom of the free market was “less than satisfying” when it came to the greenhouse effect. Ethical considerations were necessary, too. He pledged that Exxon would revise its corporate strategy to account for climate change, even if it were not “fashionable” to do so. As Exxon had already made heavy investments in nuclear and solar technology, he was “generally upbeat” that Exxon would “invent” a future of renewable energy.

Hansen had reason to feel upbeat himself. If the world’s largest oil-and-gas company supported a new national energy model, the White House would not stand in its way. The Reagan administration was hostile to change from within its ranks. But it couldn’t be hostile to Exxon.

The carbon-dioxide issue was beginning to receive major national attention — Hansen’s own findings had become front-page news, after all. What started as a scientific story was turning into a political story.

The political realm was itself a kind of Mirror World, a parallel reality that crudely mimicked our own. It shared many of our most fundamental laws, like the laws of gravity and inertia and publicity. And if you applied enough pressure, the Mirror World of politics could be sped forward to reveal a new future. Hansen was beginning to understand that too.

1. ‘Caution, Not Panic’ 1983-1984

in the fall of 1983, the climate issue entered an especially long, dark winter. And all because of a single report that had done nothing to change the state of climate science but transformed the state of climate politics.

After the publication of the Charney report in 1979, Jimmy Carter had directed the National Academy of Sciences to prepare a comprehensive, $1 million analysis of the carbon-dioxide problem: a Warren Commission for the greenhouse effect. A team of scientist-dignitaries — among them Revelle, the Princeton modeler Syukuro Manabe and the Harvard political economist Thomas Schelling, one of the intellectual architects of Cold War game theory — would review the literature, evaluate the consequences of global warming for the world order and propose remedies

Then Reagan won the White House.

the incipient report served as the Reagan administration’s answer to every question on the subject. There could be no climate policy, Fred Koomanoff and his associates said, until the academy ruled. In the Mirror World of the Reagan administration, the warming problem hadn’t been abandoned at all. A careful, comprehensive solution was being devised. Everyone just had to wait for the academy’s elders to explain what it was.

The committee’s chairman, William Nierenberg — a Jason, presidential adviser and director of Scripps, the nation’s pre-eminent oceanographic institution — argued that action had to be taken immediately, before all the details could be known with certainty, or else it would be too late.

Better to bet on American ingenuity to save the day. Major interventions in national energy policy, taken immediately, might end up being more expensive, and less effective, than actions taken decades in the future, after more was understood about the economic and social consequences of a warmer planet. Yes, the climate would change, mostly for the worst, but future generations would be better equipped to change with it.

Government officials who knew Nierenberg were not surprised by his conclusions: He was an optimist by training and experience, a devout believer in the doctrine of American exceptionalism, one of the elite class of scientists who had helped the nation win a global war, invent the most deadly weapon conceivable and create the booming aerospace and computer industries. America had solved every existential problem it had confronted over the previous generation; it would not be daunted by an excess of carbon dioxide. Nierenberg had also served on Reagan’s transition team. Nobody believed that he had been directly influenced by his political connections, but his views — optimistic about the saving graces of market forces, pessimistic about the value of government regulation — reflected all the ardor of his party.

That’s what Nierenberg wrote in “Changing Climate.” But it’s not what he said in the press interviews that followed. He argued the opposite: There was no urgent need for action. The public should not entertain the most “extreme negative speculations” about climate change (despite the fact that many of those speculations appeared in his report). Though “Changing Climate” urged an accelerated transition to renewable fuels, noting that it would take thousands of years for the atmosphere to recover from the damage of the last century, Nierenberg recommended “caution, not panic.” Better to wait and see

The damage of “Changing Climate” was squared by the amount of attention it received. Nierenberg’s speech in the Great Hall, being one-500th the length of the actual assessment, received 500 times the press coverage. As The Wall Street Journal put it, in a line echoed by trade journals across the nation: “A panel of top scientists has some advice for people worried about the much-publicized warming of the Earth’s climate: You can cope.”

On “CBS Evening News,” Dan Rather said the academy had given “a cold shoulder” to a grim, 200-page E.P.A. assessment published earlier that week (titled “Can We Delay a Greenhouse Warming?”; the E.P.A.’s answer, reduced to a word, was no). The Washington Post described the two reports, taken together, as “clarion calls to inaction.

George Keyworth II, Reagan’s science adviser. Keyworth used Nierenberg’s optimism as reason to discount the E.P.A.’s “unwarranted and unnecessarily alarmist” report and warned against taking any “near-term corrective action” on global warming. Just in case it wasn’t clear, Keyworth added, “there are no actions recommended other than continued research.”

Edward David Jr., two years removed from boasting of Exxon’s commitment to transforming global energy policy, told Science that the corporation had reconsidered. “Exxon has reverted to being mainly a supplier of conventional hydrocarbon fuels — petroleum products, natural gas and steam coal,” David said. The American Petroleum Institute canceled its own carbon-dioxide research program, too.

Exxon soon revised its position on climate-change research. In a presentation at an industry conference, Henry Shaw cited “Changing Climate” as evidence that “the general consensus is that society has sufficient time to technologically adapt to a CO₂ greenhouse effect.” If the academy had concluded that regulations were not a serious option, why should Exxon protest

2. ‘You Scientists Win’ 1985

3. The Size of The Human Imagination Spring-Summer 1986

Curtis Moore’s proposal: Use ozone to revive climate. The ozone hole had a solution — an international treaty, already in negotiation. Why not hitch the milk wagon to the bullet train? Pomerance was skeptical. The problems were related, sure: Without a reduction in CFC emissions, you didn’t have a chance of averting cataclysmic global warming. But it had been difficult enough to explain the carbon issue to politicians and journalists; why complicate the sales pitch? Then again, he didn’t see what choice he had. The Republicans controlled the Senate, and Moore was his connection to the Senate’s environmental committee.

Pomerance met with Senator John Chafee, a Republican from Rhode Island, and helped persuade him to hold a double-barreled hearing on the twin problems of ozone and carbon dioxide on June 10 and 11, 1986

F.Sherwood Rowland, Robert Watson, a NASA scientist, and Richard Benedick, the administration’s lead representative in international ozone negotiations, would discuss ozone; James Hansen, Al Gore, the ecologist George Woodwell and Carl Wunsch, a veteran of the Charney group, would testify about climate change.

As Pomerance had hoped, fear about the ozone layer ensured a bounty of press coverage for the climate-change testimony. But as he had feared, it caused many people to conflate the two crises. One was Peter Jennings, who aired the video on ABC’s “World News Tonight,” warning that the ozone hole “could lead to flooding all over the world, also to drought and to famine.”

The confusion helped: For the first time since the “Changing Climate” report, global-warming headlines appeared by the dozen. William Nierenberg’s “caution, not panic” line was inverted. It was all panic without a hint of caution: “A Dire Forecast for ‘Greenhouse’ Earth” (the front page of The Washington Post); “Scientists Predict Catastrophes in Growing Global Heat Wave” (Chicago Tribune); “Swifter Warming of Globe Foreseen” (The New York Times).

After three years of backsliding and silence, Pomerance was exhilarated to see interest in the issue spike overnight. Not only that: A solution materialized, and a moral argument was passionately articulated — by Rhode Island’s Republican senator no less. “Ozone depletion and the greenhouse effect can no longer be treated solely as important scientific questions,” Chafee said. “They must be seen as critical problems facing the nations of the world, and they are problems that demand solutions.”

The old canard about the need for more research was roundly mocked — by Woodwell, by a W.R.I. colleague named Andrew Maguire, by Senator George Mitchell, a Democrat from Maine. “Scientists are never 100 percent certain,” the Princeton historian Theodore Rabb testified. “That notion of total certainty is something too elusive ever to be sought.” As Pomerance had been saying since 1979, it was past time to act. Only now the argument was so broadly accepted that nobody dared object.

The ozone hole, Pomerance realized, had moved the public because, though it was no more visible than global warming, people could be made to see it. They could watch it grow on video. Its metaphors were emotionally wrought: Instead of summoning a glass building that sheltered plants from chilly weather (“Everything seems to flourish in there”), the hole evoked a violent rending of the firmament, inviting deathly radiation. Americans felt that their lives were in danger. An abstract, atmospheric problem had been reduced to the size of the human imagination. It had been made just small enough, and just large enough, to break through.

Four years after “Changing Climate,” two years after a hole had torn open the firmament and a month after the United States and more than three dozen other nations signed a treaty to limit use of CFCs, the climate-change corps was ready to celebrate. It had become conventional wisdom that climate change would follow ozone’s trajectory. Reagan’s E.P.A. administrator, Lee M. Thomas, said as much the day he signed the Montreal Protocol on Substances That Deplete the Ozone Layer (the successor to the Vienna Convention), telling reporters that global warming was likely to be the subject of a future international agreement

Congress had already begun to consider policy — in 1987 alone, there were eight days of climate hearings, in three committees, across both chambers of Congress; Senator Joe Biden, a Delaware Democrat, had introduced legislation to establish a national climate-change strategy. And so it was that Jim Hansen found himself on Oct. 27 in the not especially distinguished ballroom of the Quality Inn on New Jersey Avenue, a block from the Capitol, at “Preparing for Climate Change,” which was technically a conference but felt more like a wedding.

John Topping was an old-line Rockefeller Republican, a Commerce Department lawyer under Nixon and an E.P.A. official under Reagan. He first heard about the climate problem in the halls of the E.P.A. in 1982 and sought out Hansen, who gave him a personal tutorial. Topping was amazed to discover that out of the E.P.A.’s 13,000-person staff, only seven people, by his count, were assigned to work on climate, though he figured it was more important to the long-term security of the nation than every other environmental issue combined.

Glancing around the room, Jim Hansen could chart, like an arborist counting rings on a stump, the growth of the climate issue over the decade. Veterans like Gordon MacDonald, George Woodwell and the environmental biologist Stephen Schneider stood at the center of things. Former and current staff members from the congressional science committees (Tom Grumbly, Curtis Moore, Anthony Scoville) made introductions to the congressmen they advised. Hansen’s owlish nemesis Fred Koomanoff was present, as were his counterparts from the Soviet Union and Western Europe. Rafe Pomerance’s cranium could be seen above the crowd, but unusually he was surrounded by colleagues from other environmental organizations that until now had shown little interest in a diffuse problem with no proven fund-raising record. The party’s most conspicuous newcomers, however, the outermost ring, were the oil-and-gas executives.

That evening, as a storm spat and coughed outside, Rafe Pomerance gave one of his exhortative speeches urging cooperation among the various factions, and John Chafee and Roger Revelle received awards; introductions were made and business cards earnestly exchanged. Not even a presentation by Hansen of his research could sour the mood. The next night, on Oct. 28, at a high-spirited dinner party in Topping’s townhouse on Capitol Hill, the oil-and-gas men joked with the environmentalists, the trade-group representatives chatted up the regulators and the academics got merrily drunk. Mikhail Budyko, the don of the Soviet climatologists, settled into an extended conversation about global warming with Topping’s 10-year-old son. It all seemed like the start of a grand bargain, a uniting of factions — a solution.

Hansen was accustomed to the bureaucratic nuisances that attended testifying before Congress; before a hearing, he had to send his formal statement to NASA headquarters, which forwarded it to the White House’s Office of Management and Budget for approval. “Major greenhouse climate changes are a certainty,” he had written. “By the 2010s [in every scenario], essentially the entire globe has very substantial warming.”

By all appearances, plans for major policy continued to advance rapidly. After the Johnston hearing, Timothy Wirth, a freshman Democratic senator from Colorado on the energy committee, began to plan a comprehensive package of climate-change legislation — a New Deal for global warming. Wirth asked a legislative assistant, David Harwood, to consult with experts on the issue, beginning with Rafe Pomerance, in the hope of converting the science of climate change into a new national energy policy.

In March 1988, Wirth joined 41 other senators, nearly half of them Republicans, to demand that Reagan call for an international treaty modeled after the ozone agreement. Because the United States and the Soviet Union were the world’s two largest contributors of carbon emissions, responsible for about one-third of the world total, they should lead the negotiations. Reagan agreed. In May, he signed a joint statement with Mikhail Gorbachev that included a pledge to cooperate on global warming.

Al Gore himself had, for the moment, withdrawn his political claim to the issue. In 1987, at the age of 39, Gore announced that he was running for president, in part to bring attention to global warming, but he stopped emphasizing it after the subject failed to captivate New Hampshire primary voters.

5. ‘You Will See Things That You Shall Believe’ Summer 1988

It was the hottest and driest summer in history. Everywhere you looked, something was bursting into flames. Two million acres in Alaska incinerated, and dozens of major fires scored the West. Yellowstone National Park lost nearly one million acres. Smoke was visible from Chicago, 1,600 miles away.

In Nebraska, suffering its worst drought since the Dust Bowl, there were days when every weather station registered temperatures above 100 degrees. The director of the Kansas Department of Health and Environment warned that the drought might be the dawning of a climatic change that within a half century could turn the state into a desert.

On June 22 in Washington, where it hit 100 degrees, Rafe Pomerance received a call from Jim Hansen, who was scheduled to testify the following morning at a Senate hearing called by Timothy Wirth. “I hope we have good media coverage tomorrow,” Hansen said.

Hansen had just received the most recent global temperature data. Just over halfway into the year, 1988 was setting records. Already it had nearly clinched the hottest year in history. Ahead of schedule, the signal was emerging from the noise. “I’m going to make a pretty strong statement,” Hansen said.

Hansen returned to his testimony. He wrote: “The global warming is now large enough that we can ascribe with a high degree of confidence a cause-and-effect relationship to the greenhouse effect.” He wrote: “1988 so far is so much warmer than 1987, that barring a remarkable and improbable cooling, 1988 will be the warmest year on record.” He wrote: “The greenhouse effect has been detected, and it is changing our climate now.”

“We have only one planet,” Senator Bennett Johnston intoned. “If we screw it up, we have no place to go.” Senator Max Baucus, a Democrat from Montana, called for the United Nations Environment Program to begin preparing a global remedy to the carbon-dioxide problem. Senator Dale Bumpers, a Democrat of Arkansas, previewed Hansen’s testimony, saying that it “ought to be cause for headlines in every newspaper in America tomorrow morning.” The coverage, Bumpers emphasized, was a necessary precursor to policy. “Nobody wants to take on any of the industries that produce the things that we throw up into the atmosphere,” he said. “But what you have are all these competing interests pitted against our very survival.”

Hansen, wiping his brow, spoke without affect, his eyes rarely rising from his notes. The warming trend could be detected “with 99 percent confidence,” he said. “It is changing our climate now.” But he saved his strongest comment for after the hearing, when he was encircled in the hallway by reporters. “It is time to stop waffling so much,” he said, “and say that the evidence is pretty strong that the greenhouse effect is here.”

The press followed Bumpers’s advice. Hansen’s testimony prompted headlines in dozens of newspapers across the country, including The New York Times, which announced, across the top of its front page: “Global Warming Has Begun, Expert Tells Senate.”

Rafe Pomerance called his allies on Capitol Hill, the young staff members who advised politicians, organized hearings, wrote legislation. We need to finalize a number, he told them, a specific target, in order to move the issue — to turn all this publicity into policy. The Montreal Protocol had called for a 50 percent reduction in CFC emissions by 1998. What was the right target for carbon emissions? It wasn’t enough to exhort nations to do better. That kind of talk might sound noble, but it didn’t change investments or laws. They needed a hard goal — something ambitious but reasonable. And they needed it soon: Just four days after Hansen’s star turn, politicians from 46 nations and more than 300 scientists would convene in Toronto at the World Conference on the Changing Atmosphere, an event described by Philip Shabecoff of The New York Times as “Woodstock for climate change.”

Pomerance had a proposal: a 20 percent reduction in carbon emissions by 2000. Ambitious, Harwood said. In all his work planning climate policy, he had seen no assurance that such a steep drop in emissions was possible. Then again, 2000 was more than a decade off, so it allowed for some flexibility.

Mintzer pointed out that a 20 percent reduction was consistent with the academic literature on energy efficiency. Various studies over the years had shown that you could improve efficiency in most energy systems by roughly 20 percent if you adopted best practices.

Of course, with any target, you had to take into account the fact that the developing world would inevitably consume much larger quantities of fossil fuels by 2000. But those gains could be offset by a wider propagation of the renewable technologies already at hand — solar, wind, geothermal. It was not a rigorous scientific analysis, Mintzer granted, but 20 percent sounded plausible. We wouldn’t need to solve cold fusion or ask Congress to repeal the law of gravity. We could manage it with the knowledge and technology we already had.

Besides, Pomerance said, 20 by 2000 sounds good.

The conference’s final statement, signed by all 400 scientists and politicians in attendance, repeated the demand with a slight variation: a 20 percent reduction in carbon emissions by 2005. Just like that, Pomerance’s best guess became global diplomatic policy.

Hansen, emerging from Anniek’s successful cancer surgery, took it upon himself to start a one-man public information campaign. He gave news conferences and was quoted in seemingly every article about the issue; he even appeared on television with homemade props. Like an entrant at an elementary-school science fair, he made “loaded dice” out of sections of cardboard and colored paper to illustrate the increased likelihood of hotter weather in a warmer climate. Public awareness of the greenhouse effect reached a new high of 68 percent

global warming became a major subject of the presidential campaign. While Michael Dukakis proposed tax incentives to encourage domestic oil production and boasted that coal could satisfy the nation’s energy needs for the next three centuries, George Bush took advantage. “I am an environmentalist,” he declared on the shore of Lake Erie, the first stop on a five-state environmental tour that would take him to Boston Harbor, Dukakis’s home turf. “Those who think we are powerless to do anything about the greenhouse effect,” he said, “are forgetting about the White House effect.”

His running mate emphasized the ticket’s commitment to the issue at the vice-presidential debate. “The greenhouse effect is an important environmental issue,” Dan Quayle said. “We need to get on with it. And in a George Bush administration, you can bet that we will.”

This kind of talk roused the oil-and-gas men. “A lot of people on the Hill see the greenhouse effect as the issue of the 1990s,” a gas lobbyist told Oil & Gas Journal. Before a meeting of oil executives shortly after the “environmentalist” candidate won the election, Representative Dick Cheney, a Wyoming Republican, warned, “It’s going to be very difficult to fend off some kind of gasoline tax.” The coal industry, which had the most to lose from restrictions on carbon emissions, had moved beyond denial to resignation. A spokesman for the National Coal Association acknowledged that the greenhouse effect was no longer “an emerging issue. It is here already, and we’ll be hearing more and more about it.”

By the end of the year, 32 climate bills had been introduced in Congress, led by Wirth’s omnibus National Energy Policy Act of 1988. Co-sponsored by 13 Democrats and five Republicans, it established as a national goal an “International Global Agreement on the Atmosphere by 1992,” ordered the Energy Department to submit to Congress a plan to reduce energy use by at least 2 percent a year through 2005 and directed the Congressional Budget Office to calculate the feasibility of a carbon tax. A lawyer for the Senate energy committee told an industry journal that lawmakers were “frightened” by the issue and predicted that Congress would eventually pass significant legislation after Bush took office

The other great powers refused to wait. The German Parliament created a special commission on climate change, which concluded that action had to be taken immediately, “irrespective of any need for further research,” and that the Toronto goal was inadequate; it recommended a 30 percent reduction of carbon emissions

Margaret Thatcher, who had studied chemistry at Oxford, warned in a speech to the Royal Society that global warming could “greatly exceed the capacity of our natural habitat to cope” and that “the health of the economy and the health of our environment are totally dependent upon each other.”

The prime ministers of Canada and Norway called for a binding international treaty on the atmosphere; Sweden’s Parliament went further, announcing a national strategy to stabilize emissions at the 1988 level and eventually imposing a carbon tax

the United Nations unanimously endorsed the establishment, by the World Meteorological Organization and the United Nations Environment Program, of an Intergovernmental Panel on Climate Change, composed of scientists and policymakers, to conduct scientific assessments and develop global climate policy.

One of the I.P.C.C.’s first sessions to plan an international treaty was hosted by the State Department, 10 days after Bush’s inauguration. James Baker chose the occasion to make his first speech as secretary of state. “We can probably not afford to wait until all of the uncertainties about global climate change have been resolved,” he said. “Time will not make the problem go away.”

: On April 14, 1989, a bipartisan group of 24 senators, led by the majority leader, George Mitchell, requested that Bush cut emissions in the United States even before the I.P.C.C.’s working group made its recommendation. “We cannot afford the long lead times associated with a comprehensive global agreement,” the senators wrote. Bush had promised to combat the greenhouse effect with the White House effect. The self-proclaimed environmentalist was now seated in the Oval Office. It was time.

8. ‘You Never Beat The White House’ April 1989

After Jim Baker gave his boisterous address to the I.P.C.C. working group at the State Department, he received a visit from John Sununu, Bush’s chief of staff. Leave the science to the scientists, Sununu told Baker. Stay clear of this greenhouse-effect nonsense. You don’t know what you’re talking about. Baker, who had served as Reagan’s chief of staff, didn’t speak about the subject again.

despite his reputation as a political wolf, he still thought of himself as a scientist — an “old engineer,” as he was fond of putting it, having earned a Ph.D. in mechanical engineering from M.I.T. decades earlier. He lacked the reflexive deference that so many of his political generation reserved for the class of elite government scientists.

Since World War II, he believed, conspiratorial forces had used the imprimatur of scientific knowledge to advance an “anti-growth” doctrine. He reserved particular disdain for Paul Ehrlich’s “The Population Bomb,” which prophesied that hundreds of millions of people would starve to death if the world took no step to curb population growth; the Club of Rome, an organization of European scientists, heads of state and economists, which similarly warned that the world would run out of natural resources; and as recently as the mid-’70s, the hypothesis advanced by some of the nation’s most celebrated scientists — including Carl Sagan, Stephen Schneider and Ichtiaque Rasool — that a new ice age was dawning, thanks to the proliferation of man-made aerosols. All were theories of questionable scientific merit, portending vast, authoritarian remedies to halt economic progress.

When Mead talked about “far-reaching” decisions and “long-term consequences,” Sununu heard the marching of jackboots.

Sununu had suspected that the greenhouse effect belonged to this nefarious cabal since 1975, when the anthropologist Margaret Mead convened a symposium on the subject at the National Institute of Environmental Health Sciences.

While Sununu and Darman reviewed Hansen’s statements, the E.P.A. administrator, William K. Reilly, took a new proposal to the White House. The next meeting of the I.P.C.C.’s working group was scheduled for Geneva the following month, in May; it was the perfect occasion, Reilly argued, to take a stronger stand on climate change. Bush should demand a global treaty to reduce carbon emissions.

Sununu wouldn’t budge. He ordered the American delegates not to make any commitment in Geneva. Very soon after that, someone leaked the exchange to the press.

A deputy of Jim Baker pulled Reilly aside. He said he had a message from Baker, who had observed Reilly’s infighting with Sununu. “In the long run,” the deputy warned Reilly, “you never beat the White House.”

9. ‘A Form of Science Fraud’ May 1989