How Capt. Bligh is helping climate study

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Scientists are using centuries-old logbooks in the British archives to understand weather patterns

Scientists are mining the logbooks of British sea captains from the age of exploration and discovery for troves of weather data to help them understand global warming, climate change and weather variability.

A depiction of Charles Darwin's HMS Beagle in the Straits of Magellan, with Mt. Sarmiento in the distance.

The researchers have photographed entries from 300 logbooks in the British National Archives dating from 1750 to 1850 and digitized the logs’ weather readings and observations. “It’s pretty good stuff,” says project leader Dennis Wheeler, a climate scientist at the University of Sunderland in England.

Reconstructing the weather 150 to 250 years ago helps “sharpen and clarify” scientists’ understanding of today’s climate trends and variations, including global warming, he says. To date, work on the logbooks just scratches the surface of the weather data in the records of the Royal Navy. Wheeler estimates 250,000 logbooks are in the archives, some dating to 1680. “We are confident there isn’t anywhere else that has that quantity of information,” he says.

Robert FitzRoy, captain of HMS Beagle on Charles Darwin’s epic 1831-36 circumnavigation, is among the log authors. Others include Capt. James Cook, who sailed around the world twice, from 1772 to ’75 and 1776 to ’78; Pacific voyager William Bligh, captain of HMS Providence and the mutinous HMS Bounty in the 1780s and ’90s; early 19th century Arctic explorer W.E. Parry, who attempted a northwest passage on HMS Hecla and Fury; and polar explorer Capt. James Ross, who crewed for Parry and Ross’s uncle John Ross on Arctic explorations and commanded his own Antarctic expedition from 1839 to ’43.

The U.K. Colonial Registers and Royal Navy Logbooks project, or CORRAL, also has gleaned weather data from the 18th century logs of Bahamian lighthouses at Abaco, Cay Lobos, Cay Sal, Inagua, Sombrero and Watling Island; the St. Helena lighthouse in the South Atlantic; and Malden Island lighthouse in the Pacific. Those records are held in the U.K. Meteorological Archive.

Many British Navy captains of the era of exploration and discovery were sent out to chart new territories — take hydrographic soundings, map coastlines. “These explorations had a political dimension, but the ships usually carried with them one or two scientists,” says Wheeler. Their job was to observe and record.

Besides survey instruments, the ships carried thermometers to take readings of air and sea-surface temperatures, and barometers to record air pressure. Log keepers estimated wind speed and direction, and often added their own observations about the weather and, around the poles, ice cover. Readings and observations were recorded in logbooks daily, sometimes hourly.

“Ice closely packed,” reads one entry from the log of Lt. A. Morrell during an 1818 naval expedition to the North Pole aboard HMS Dorothea. “Ice seen from the mast extending from the south to north by northwest,” reads another.

The archived logbooks are an enormous lode to mine. British naval captains have been turning in their logs to record-keepers at Britain’s Admiralty for more than three centuries. Wheeler’s team still is extracting and digitizing — computerizing — 2 million pieces of data from the first 300 logbooks.

“We’ve still got much to do, and it’s going to take a very long time,” says Wheeler.

Artist Richard Bentley depicted the HMS Dorothea's failed attempt to reach the North Pole under Capt. David Buchan in 1818.

The researchers have focused most of their initial effort on digitizing data from the early Arctic explorers because of critical interest in the shrinking polar ice caps. Are the causes natural or human? Wheeler says it’s far too early to draw any conclusions from the logbooks.

Different logs yield conflicting observations. An analysis of the 1818 voyage of the Dorothea, which stopped its search for the North Pole near Svalbard in the Norwegian Arctic because of sea ice, suggests that Arctic temperatures thereabouts that summer were “not markedly colder” than summer temperatures typical in the late 20th century. Sea ice was “greater than that seen in the last few years but within the range covered by the years 1961-90,” their analysis reveals.

Temperature readings taken aboard Isabella, a Royal Navy vessel seeking to make a northwest passage through the Arctic, indicate that on Baffin Bay the “summer of 1818 was slightly colder than was typical in the late 20th century,” according to researchers, who concluded the ice pack was still similar to the 1961-90 range.

Wheeler says data from the CORRAL project can help reconstruct historic weather patterns and variations over a 100-year period before the full onset of the industrial age, giving researchers a baseline of information to work from. However, he notes that two unusual natural events — the 1815 volcanic eruption of Indonesia’s Mount Tambora, the largest ever recorded, and a period of minimal sunspot activity in the early 1800s — would have had a significant influence on the weather during the early 19th century time frame under study.

The CORRAL project is part of a larger worldwide effort to tap old weather records to help understand today’s climate trends. ACRE, or Atmospheric Circulation Reconstructions over the Earth, is an international collaboration to gather historical weather data from around the world and reconstruct daily global weather and atmospheric conditions over the last 200 to 250 years. The U.S. National Oceanic and Atmospheric Administration, the University of Colorado, the United Kingdom’s Met (weather) Office and the Australian Bureau of Meteorology are the principal partners among some 30 international collaborators, says Met’s Rob Allan, who manages the ACRE project.

“We can reconstruct the weather right up through the atmosphere from surface observations,” says Allan — mainly air and sea-surface temperatures, wind speed and direction, rainfall and barometric readings, and sea-ice observations.

New sources of data are surfacing all the time. Wheeler estimates there are at least 8,000 ships’ logs in Dutch archives and another 20,000 in French repositories. One of the big pushes now is to tap an estimated 2,000 logs of ships that sailed to India and China from the 1790s to 1830s for the British East Indies Company. Other sources include weather offices (mainly after the 1850s); Jesuit missionaries in Cuba, the Philippines, China and elsewhere (they were faithful record keepers); pilot boat stations; harbormasters; consular records; and records of universities, hospitals and military installations.

“There’s a lot more out there than people anticipated,” Allan says.

“Hindcasting” — using forecasting models to crunch historical weather data to reconstruct weather patterns from years past — can be used not just by climate scientists but also by agricultural concerns and the reinsurance industry to project future climate trends and variability, Allan says.

Yet the most valuable contribution of the old logbooks may be a better understanding of “how climate has naturally varied over the centuries and what changes [today] are occurring from global warming,” according to Allan.

Their careful observations can help our understanding.

This article originally appeared in the January 2010 issue.