Icebound - The climate-change secrets of 19th century ship's logbooks

On November 14, 1881, an American called George Melville limped across a frozen delta in Siberia and pulled a pole from the snow with his frost-bitten hands.

Exhausted and half-starving, Melville was scouring the wasteland for fellow survivors of the most famous ship in the world. The USS Jeannette had set sail from San Francisco to conquer the North Pole. Instead, it quickly got trapped in ice and spent nearly two years drifting across the Arctic Ocean, lost to the rest of humanity.

When it was finally crushed by the ice, the Jeannette's 33 crew members set out across the frozen sea. A storm separated them, and Melville mustered a team of locals in the desolate Lena Delta to find his missing shipmates. He braved the wilderness as the days grew shorter, his legs so swollen and blistered from exposure that he vomited with the pain.

First he found the pole. It marked the spot where George De Long, the Jeannette's captain, had buried the valuables he had grown too weak to carry. They included Captain De Long's most prized possessions: the ship's four logbooks. These hefty, leather-bound volumes recorded, in intimate detail, the ill-fated Jeannette expedition and the discoveries it had made.

It took Melville four more months to find De Long's body. Nineteen other crew members also died, their heroic lives cut short by drowning, disease, exposure and starvation. But, thanks to Melville, the logbooks survived. Once, while battling through a snowstorm, he briefly considered reburying them to lighten his load, then changed his mind. "Setting my teeth against the storm," he wrote, "I would swear a new oath to carry them through, let come what might."

Thousands of miles away, and 138 years later, the Jeannette's logbooks sit in a climate-controlled room in the U.S. National Archives in Washington, D.C. Every page has been digitized and uploaded to the web, then transcribed by an eccentric group of citizen-scientists called Old Weather.

For the past decade, its far-flung volunteers have shown that the Jeannette's logbooks, and others like them, are more than what Melville called "the records … of our two years of toil and suffering." They are rich repositories of data that can help us understand how profoundly the Earth's climate has changed and what might happen to it in the future.

Meteorologists have long recorded the weather at land-based stations. But nearly three-quarters of the planet is covered by water, and that's where most weather takes place. Thousands of ships have criss-crossed the oceans, noting the weather in handwritten logbooks that for decades sat forgotten in bookshelves and basements.

In a sometimes-obsessive quest, thousands of Old Weather volunteers have extracted millions of observations about barometric pressure, wind speed, air temperature and ice from the old logbooks. These are fed into a huge dataset at the U.S. National Oceanic and Atmospheric Administration, creating what NOAA calls "a dauntingly complex, high-resolution, four-dimensional reconstruction of the global climate that estimates what the weather was for every day back to 1836."

Or, as NOAA has nicknamed it, "a weather time machine."

Many of the ships, like the Jeannette, hail from the great era of Arctic exploration, when crews risked everything in a race for the North Pole. Ships plunged into the frozen unknown and vanished, inspiring other ships to launch daring but luckless missions to rescue them. In an age when Arctic ice is fast disappearing, many Old Weather volunteers also see their work as a rescue mission, but with much higher stakes, as the warming Earth makes its own leap into the unknown.

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