As negotiators prepare to gather in Copenhagen next month to try and reach an agreement to halt climate change, the world's leading scientists have come to an alarming conclusion: Global warming is happening even faster than they thought.
The Arctic, it turns out, is melting so quickly that even top ice experts are stunned. Just a few years ago, scientists were assuring us that we wouldn't have an ice-free Arctic until 2100. Now the data suggests that, within a decade or two, there will be sailboats at the North Pole during the summer. The melting Arctic is a ticking time bomb for the Earth's climate - and thanks to our failure to reduce greenhouse-gas pollution, the fuse has already been lit. "It's like man is taking the lid off the northern part of the planet," said Peter Wadhams, an ice expert at the University of Cambridge in England.
The Arctic is more than just a frozen block of ice — it's more like a frozen block of carbon. Beneath the ice, the region is covered with a slab of permafrost — more than 1,000 feet thick in some places —composed of partially decomposed trees, plants, woolly mammoths and other organic matter that lived in the region thousands of years ago. As it thaws, all that rotting debris sends carbon dioxide into the atmosphere. Worse, the debris is a feast for microscopic bugs that transform it into methane, a greenhouse gas at least 20 times more potent than CO2. All told, there are some 1 trillion metric tons of carbon buried in the Arctic — the equivalent of the oil, gas and coal reserves on the entire planet. From a planetary perspective, melting the Arctic is like firing up the world's largest furnace — one that will belch catastrophic levels of greenhouse gases into the atmosphere.
But that's not the worst of it. A similarly huge amount of methane is frozen in the floor of the shallow seas surrounding the Arctic. As the water warms, these blocks of methane ice can bubble to the surface and release millions of tons of methane — more or less cooking the planet overnight. "If that happens," says Jim White, head of the Institute of Arctic and Alpine Research at the University of Colorado, "we are hosed."
Even without a sudden release of methane, what's happening in the Arctic has created an ever-accelerating feedback loop that is already speeding up the rate of climate change. As the ice melts, it creates more open water, which absorbs heat faster, which melts ice faster, which warms the water more — and on and on. "One of the biggest questions in climate science is how fast these amplifying feedback loops accelerate," says Ken Caldeira, a climate modeler at the Carnegie Institution. One study found that during periods of rapid sea-ice loss, the land warms three times faster than average, amplifying the feedback loop and further accelerating warming.
A warmer Arctic is likely to have a major impact on our weather; some scientists argue that the loss of summer sea ice is already partly responsible for freakish weather events, such as the recent snowstorm in Baghdad. "The Arctic is the global refrigerator for the northern hemisphere," says Mark Serreze, a scientist at the National Snow and Ice Data Center in Colorado. "If you change it, you're likely to see a variety of effects, including drier summers in the southwest United States and wetter winters in the Mediterranean."
Even more alarming, rising temperatures in the Arctic threaten to melt the Greenland ice sheets faster than expected. Only two years ago, a United Nations climate report predicted that the seas would likely rise by no more than 23 inches by 2100. Now, thanks largely to the radical changes in the Arctic in the past few years, scientists believe that even if we take drastic action and cut emissions quickly, we're still likely to see sea levels rise by as much as three feet. And if we don't take action, warns NASA's James Hansen, America's most respected climate scientist, sea levels could rise by as much as nine feet by the end of the century. Such a rise would be catastrophic for many of the world's major cities, including New Orleans, London and Shanghai, as well as the 40 million or so people who live in low-lying areas in poor nations like Bangladesh.
The big question is, is it too late to avert catastrophe? No one knows. "We do not yet have a clear signal of significant methane release from the permafrost," says Ed Dlugokencky, a methane expert with the National Oceanic and Atmospheric Administration. "But we know that as the region heats up, it is inevitable." Once the Arctic is gone, it won't be coming back anytime soon — which is why cutting greenhouse-gas pollution now is so important. As Lonnie Thompson, a glacier expert at Ohio State University, has put it, "Mother Nature is the timekeeper — and nobody can see the clock."