My hiking companion and I have lost our way on this damp late-summer morning. We're on a treeless, mist-shrouded hilltop in Snowdonia National Park, 1,000 feet or so above the Irish Sea along the coast of northern Wales. The bleating of sheep drifts up from the slopes below, muffled by fog that hides the lay of the land. We're trying to reach a village called -- by those able to pronounce its name -- Abergynolwyn, which lies in a nearby valley. But with the murk, we can't find the way down. Sir John Houghton pulls a topographic map and a compass from his backpack. After a few moments of thought he says, "We want to head north. That should take us downhill." So we follow a sheep trail, and a bit later I watch Houghton, who is 76, nimbly hoist himself over a chest-high wire fence.
Charting a path through difficult terrain is nothing new for Houghton, who may be the most important scientist you've never heard of. From 1988 until his semi-retirement in 2002, he was one of the leaders of the Intergovernmental Panel on Climate Change (IPCC), a body created by the United Nations 20 years ago to study global warming. As cochairman of the IPCC's scientific working group, Houghton had to coordinate the efforts -- and cope with the egos -- of more than 2,000 scientists from dozens of countries. Against all odds, the IPCC, which could have been a fractious and unwieldy international boondoggle, produced a series of authoritative and scientifically rigorous reports firmly establishing the magnitude of the threat posed by climate change. Largely because of the efforts of Houghton's group, the IPCC shared the 2007 Nobel Peace Prize with Al Gore.
Houghton has been at the forefront of climate research for decades. He started investigating global warming more than 40 years ago, after joining the department of atmospheric physics at Oxford University. From 1983 until 1991 he was the head of the Met (short for Meteorological) Office, the United Kingdom's national weather service. He served as chairman of the Royal Commission on Environmental Pollution for much of the 1990s. However, the affiliation that means most to him is one rarely associated with a serious commitment to science or environmental activism. Houghton is a devout evangelical Christian.
"I'm constantly asking myself, why on earth should I believe in Christianity? Do I really believe it?" he says to me, discussing his faith while we pause for lunch beside a logging road. "It seems so impossible to believe in. But then I ask, can I not believe it?"
Houghton's faith is central to his response to the hard, inescapable reality of global warming. He believes we can still save the world from the worst effects of climate change, but he is also very specific about how little time we have left -- seven years. Despite the imminence of calamity, he remains hopeful that we will overcome the threat -- if the developed world recognizes that global warming is as much a moral and spiritual problem as an environmental one.
I first met Houghton at a talk he gave at Cambridge University earlier in the summer. He is a slender, elegant man, with a hawklike profile, deep-set blue eyes, and thinning white hair. He devoted the first half of his talk entirely to the science of global warming, arguing that we are already seeing its first effects in events like the heat wave that struck central Europe in 2003 and is estimated to have caused more than 20,000 premature deaths.
Then Houghton changed gears. The talk became intensely personal, a profession of his Christian faith. He called global warming "a weapon of mass destruction" and said that the rich nations of the world, which have generated most of the greenhouse gases, have a moral obligation to solve the problem. "We're generally good at sharing in families, communities, and nationally, but not so good globally," he said. "If the Old Testament prophets were here, they'd be tearing their hair out, cursing us, telling us we're absolutely greedy, and they'd be right."
The frank discussion of faith from such an eminent scientist surprised me, and I asked Houghton if I could speak with him at more length. He invited me to spend a couple of days at his home in Aberdovey.
Houghton and his wife, Sheila, live in a renovated farmhouse on a hillside overlooking a broad, calm estuary where the river Dovey empties into Cardigan Bay. The "Aber" in Aberdovey is Welsh for "mouth of the river." Outward Bound, the outdoor education program, began in Aberdovey in 1941. One of the school's original buildings still stands on the hillside below Houghton's home. I spend the night in their guesthouse, once a barn, and I awake in the morning to find a small refrigerator stocked with cereal, fruit, eggs, milk, and orange juice from Cuba with a fair-trade logo on the carton. Houghton's wife, it turns out, owns a small fair-trade shop in a neighboring town.
After breakfast, and before setting off on our hike, Houghton and I talk for a while in a sitting room with sweeping views of the bay and river. Beyond the Dovey, hazy, serried ranks of hills rise over the bay. A light breeze ferries low gray clouds inland from the sea; the tide is coming in, gradually covering the river's sandbars as Houghton talks quietly, almost shyly, about his religious beliefs, and how he sees no need to separate them from his career as a scientist.
"The science we're doing is God's science," he says. "If we find things out about the world, we're finding out about God's universe and the way he runs it, while recognizing that there are many things we don't understand. You wonder how things fit, and sometimes we have to say we don't know. One of the most important statements a scientist can make is 'I don't know.' And one of the most important statements a theologian can make is 'I don't know.' There are so many things we don't know and so many things to find out, which is why it's such an interesting place, the universe."
But there are some things scientists know all too well, and one of them is that the world is growing inexorably warmer. By the end of this century the average global temperature is expected to increase by 2 to 6 degrees centigrade (3.5 to 11 degrees Fahrenheit).
Houghton believes that an increase of 2 degrees centigrade over the preindustrial average is probably inevitable. It's also a number that would be perilous to exceed. "If we get up to 3 degrees, the damage becomes much greater," he says. "The evidence is that 2 degrees is about the limit. Are we running out of time? The answer is yes. If we want to limit the global temperature increase to 2 degrees, the peak in our emission of greenhouse gases has to occur in 2015. We have seven years. Now, is that going to happen? If there is political will, we'll do it."
Houghton stands up and suggests we set out for our hike. So we get into his Prius, a 2001 model, the first year the car was available outside Japan, and drive along the coast for about 20 minutes to a trailhead at Dolgoch Falls, a series of three waterfalls that spill through a wooded ravine near an old narrow-gauge railroad.
As we walk uphill, Houghton talks about his childhood. His father was a school principal in North Wales. His mother taught mathematics. "My father was a very devout Christian man, a Baptist with strong conservative views," he says. "He was very much an anti-evolutionist. He thought it was just completely incompatible with any Christian belief. From an early age that seemed wrong to me. Because if you believe this is God's universe, and science is studying what the universe is all about, then there can't be a conflict."
Houghton attended Oxford on a full scholarship. He was a freshman in 1948, a time when the university was filled with men returning to school after the war. "I was a slightly lost teenager amongst these older men," he says. "But they were very nice chaps, and guided me. I joined a Christian union group, which was a great help in thinking through my faith and in supporting my intuition that religious faith is not incompatible with a scientific outlook."
Houghton gave his first lecture on global warming in 1967, nine years before he became a professor of atmospheric physics at Oxford. At the time only a handful of scientists were studying the effects of carbon dioxide on the atmosphere. Houghton and his colleagues saw the gas's warming effect as an interesting scientific problem, not a nascent threat.
Two developments ended that age of innocence. One was the advent of satellites, which allowed scientists to monitor the entire atmosphere. The second was the development of powerful computers for modeling climate change. "Satellites opened our eyes to a measurement future that we just couldn't have imagined," Houghton says. "We had been getting measurements from aircraft, balloons. Now here was a vehicle going around the world, looking at the whole world twice a day!"
By the 1980s, evidence was mounting that human actions were affecting the climate on a global scale. In 1988, Houghton was invited to co-chair the IPCC's scientific working group. It was while serving on the IPCC, says Houghton, that his religious outlook began to seriously inform his scientific work. "Among the people working on science for the IPCC, there were some I knew to be Christians. We talked about the moral side of climate change too. We prayed that we might succeed in doing an honest job. That was a great solace for me."
Houghton is emphatic that there can be no contradiction between his faith and his work as a scientist. He said, "More and more as I worked on the IPCC reports, I began to examine the consequences of what we in the developed world were doing, and I realized that global warming was something the rich were responsible for. The moral imperative to do something about it is very, very strong. The developed world has to take the first action in reducing greenhouse gas emissions. That part is inescapable."
When the panel issued its second report in 1995, 80 governments had signed off on it. That report reached a cautious conclusion, summarized in one sentence that required more than an hour of haggling before it was finally approved: "The balance of evidence suggests a discernible human influence on climate."
Last year the IPCC released its fourth major report. It concluded that the evidence for global warming was "unequivocal" and that human contributions were "very likely" to blame. It also stated that with immediate action the world could avoid many of the worst consequences.
Houghton and I have nearly reached Abergynolwyn, where we'll catch a train back to the trailhead at Dolgoch Falls. He points to some deep holes on a hillside across the valley. "Those are old mine shafts," he says. "There was quite a bit of mining in this area in the nineteenth century -- mining for slate, for copper; some lead mines."
In those days the consequences of consumption lay close at hand. Today's global economy buffers us from the effects of a lifestyle that ravages the world. Each person in the United States consumes about 120 times the amount of resources as someone in Bangladesh. That disparity is -- or should be -- the great moral issue of our time, says Houghton.
He believes that the challenge of global warming offers the developed world a chance for moral regeneration, and in that sense might be good news -- which is the literal meaning of the word gospel. It's a point of view shared by Michael Northcott, an Anglican priest and friend of Houghton's. I'd spoken a few days earlier with Northcott at the University of Edinburgh, where he is a professor of ethics.
"Living lower down on the food chain environmentally will also be good for our souls," Northcott told me. "Jesus reckoned that wealth was the biggest threat to human spiritual health. Jesus didn't say it would be very hard for a gay person to get into the kingdom of heaven, or that it would be very hard for a divorced person. He said it would be very hard for a rich man. Cheap energy has made us rich. We will need to be a little less rich, I think. Right now the world's developed nations aren't prepared to do that, but I think it's entirely possible as an outcome."
In the absence of a morally transformed global community, Houghton says the developed world must take some practical steps now. The single most pressing challenge, he says, is to make sure that all new coal-fired power plants are equipped with technology that captures and stores their carbon dioxide emissions. China is building two coal-fired plants every week. And since a typical plant lasts 50 years, decisions about their design will affect emissions for decades to come. "We've got to get on with it," says Houghton. "We need that investment in carbon capture now!"
Despite all the challenges, Houghton remains optimistic for three reasons. First, he believes the technology and funding exist to solve the problem. He cites estimates that moving to a carbon-neutral economy would require less than 1 percent of the world's GDP. Second, he says the scientific community is committed to solving the problem. Finally, what sustains him the most is his belief that God cares for creation.
Houghton spends much of his time now trying to relay that third point to his fellow evangelicals, especially in the United States. Over the past few years he has become friendly with Richard Cizik, vice president for governmental affairs of the powerful National Association of Evangelicals, which represents some 50,000 American churches. Cizik attended a meeting that Houghton organized at Oxford, at which a number of leading climate scientists talked about global warming.
"At the end of the meeting Cizik told me he never realized that scientists could be so humble, which I thought was interesting," Houghton says. "He was impressed by the reluctance of scientists to say more than they were absolutely sure of. He describes it quite publicly as a Damascus Road experience on his part."
Since that meeting Cizik has faced an uphill battle in trying to convince his fellow evangelicals that efforts to halt global warming should be high on their political agenda. "Scientists are perceived by evangelicals to be Darwinian evolutionists," he told me in a telephone interview. "Most evangelicals reject evolution. So they reject what scientists say about climate change. Climate change becomes a victim of the evolution debate. But I'm persuaded that evangelicals can change their minds. They can get out of their iron-cage, anti-science way of thinking and become the activists behind climate change. Because if not us, who?"
Houghton says that Cizik's efforts are crucial. "The biggest problem in the world is getting the American religious right on board, because if that happened, the whole thing would be transformed."
On the morning after our hike, while sitting in Houghton's home, I notice a coffee table book called Private Views of Snowdonia, a collection of photographs of the park, accompanied by short essays. One of the photos shows Crib Goch and Moel Siabod, two peaks in Snowdonia. It carries a text by Houghton. Before catching my train to London, I ask him about the mountains.
"They're some of the finest ridge walks in Britain," he says. On the day he climbed Crib Goch and Moel Siabod, the mountains were covered with mist. Occasionally the mist broke, revealing spectacular vistas. It was, he says, a gradual process of disclosure, offering brief glimpses of a previously hidden reality. "I think heaven must be rather like that."