Old satellite data to reveal cause of Arctic ice thinning

Old satellite data to reveal cause of Arctic ice thinning

SHARE

Canada: 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 US National Snow and Ice Data Center have detailed plans for “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.

These initiatives are significant as the latest satellite data revealed that the four greatest melts in the 30-year satellite record have occurred in the past four years.

“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.

“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. 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 is behaved in the past in order that we can assess how it is 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.

More than 300 ships’ logs have previously been digitised 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 organisations.

Source: montrealgazette.com