Old satellite data, ships' logbooks could reveal history of Arctic ice
By Randy Boswell, Postmedia News January 2, 2011 9:01 AM
Old satellite data, ships' logbooks could reveal history of Arctic ice
The recent, record-setting retreat of Arctic sea ice in Canada and across the polar north has prompted separate research projects in Britain and the United States aimed at reconstructing the region's historical ice record - from the 18th century age of sail to the dawn of the satellite era in the 1960s.
A team of British researchers, set to embark on a three-year probe of archived ship logs from 1750 to 1850, intends to create a composite picture of Arctic ice cover from the journal entries of polar explorers such as Sir William Parry, whose voyages to northern Canada in the 1820s added new Arctic islands to the world map and significantly furthered the quest to discover the Northwest Passage.
Meanwhile, scientists from NASA and the U.S. National Snow and Ice Data Center have detailed plans for what's being called a "techno-archeology" experiment to extract previously unfiltered data about Arctic ice extent from some of the first satellite images of the Earth, recorded as early as 1964 by the Nimbus series of orbiting spacecraft.
In both cases, the research teams say their findings will help climatologists better understand the present-day Arctic meltdown and sharpen their forecasts of this century's ice retreat, widely expected to result in open-water summers throughout Canada's North by 2030 or sooner.
Arctic Ocean ice experienced another severe thaw last summer, the third-biggest since satellite monitoring began in 1979.
The 2010 retreat from a winter ice maximum of about 15 million square kilometres to a September coverage area of just five million square kilometres also meant that the four greatest melts in the 30-year satellite record have occurred in the past four years.
But the NASA-NSIDC project could extend that satellite record by 15 years if experts are able to tease out a profile of the Arctic ice from the pioneering pictures of the planet taken by the early Nimbus orbiters.
"Satellite sea ice records go back only to 1979, but early NASA satellites collected data over the Arctic that was never processed because of the limitations of early computers," David Gallaher, a technology expert with the Colorado-based snow and ice data centre, stated ahead of a December geology conference in San Francisco.
"Researchers have now shown that they can derive sea ice extent data from an archive of data from the Nimbus satellites, launched in the 1960s and 1970s."
Interpreting the Nimbus data is a tricky process involving painstaking analysis of reams "archaic, two-inch tape," according the NSIDC. But if the researchers can construct a high-resolution, season-by-season record of ice expansion and contraction for the 15 years before 1979, the extended timeline will provide a much clearer picture of the trends that led to this decade's alarming Arctic ice retreat.
The British project, despite its reliance on the eyewitness accounts of Royal Navy sailors, promises to expand the knowledge of Arctic ice conditions from the mid-18th to the mid-19th century.
"Ships' logbooks were the main resource used to record the weather in the oceans," the University of Sunderland said in a summary of the project issued in December. "Officers kept careful records of the daily, and sometimes hourly, climate conditions. What that means today is modern researchers are able to find what the weather was like anywhere in the world on a particular day."
Such weather records also included reports on ice conditions during northern voyages of discovery and commercial expeditions in Canada's Arctic waters for the Hudson's Bay Company.
"The Arctic environmentally is a hugely important area, but we need to know how it's behaved in the past in order that we can assess how it's going to behave in the future," said project leader Dennis Wheeler, a University of Sunderland researcher who has previously probed archived ships' logs - including records left by Capt. James Cook from his polar and Pacific voyages - to track historical temperature trends.
"This is no longer just a scientific issue; climate change is of global political concern," Wheeler said.
"The logs from search vessels for Sir John Franklin and his crew, who disappeared on their voyage to navigate the Northwest Passage, are incredibly important from both a climatology and historic perspective."
More than 300 ships' logs have previously been digitized as part of the Wheeler-led U.K. Colonial Registers and Royal Navy Logbooks (CORRAL) project.
"We are using the CORRAL data as a springboard to the Arctic project," said Wheeler, who is working on the historical ice database with the Scott Polar Research Institute and other British scientific organizations.
Sir Richard Brook, director of the Leverhulme Trust funding body that's supporting the archival project, added that "sailors into the Arctic regions, be they traders, whalers, or navy, have described their experience of climate in their logbooks. A century of insight is accessible to the patient scholar, but currently untapped."
© Copyright (c) Postmedia News
Read more:
Old satellite data, ships' logbooks could reveal history of Arctic ice
Old satellite data, ships' logbooks could reveal history of Arctic ice
Linear Mode
