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article imageLogbooks reveal Antarctic sea ice barely changed in 100 years

By Karen Graham     Nov 25, 2016 in Science
Century-old logbooks from the ships of Captain Robert Scott and Sir Ernest Shackleton, key figures from the "Heroic Age of Antarctic Exploration," have revealed that sea ice levels in the Antarctic have changed very little in the last 100 years.
The "Heroic Age of Antarctic Exploration" began at the end of the 19th century and ended in 1919 with Shackleton's Imperial Trans-Antarctic Expedition. During this period of time, 17 major expeditions were launched from 10 countries, all racing to reach the South Pole.
And while the expeditions were fraught with danger, many deaths and quite a number of failures, their efforts were not in vain, reports New Atlas. There were also many successes, such as finding the magnetic and the geographical South Pole, as well as mapping the coastline.
Piper  Gilbert Kerr  a member of the Scottish National Antarctic Expedition  plays the bagpipes for ...
Piper Gilbert Kerr, a member of the Scottish National Antarctic Expedition, plays the bagpipes for an indifferent penguin, March 1904.
William S Bruce 1867-1921
Researchers Tom Edinburgh and Jonathan J. Day, with the Department of Meteorology, University of Reading, using logbooks and journals from those early expeditions, have discovered that sea ice levels in Antarctica have changed very little over the past century.
Their findings, published in the journal The Cryosphere on November 21, 2016, are somewhat counter-intuitive to what has been happening at the South Pole over the past several years, with Antarctic ice shelves shrinking by as much as 159 billion tons each year. Interestingly, the research shows that this may be part of a long-term cycle.
Using the logbooks of the early explorers, the researchers compared where the ice edges were observed then, and compared them to recent observations of the ice edges. They found that in the past century, sea ice levels had only dropped about 14 percent during Antarctica's summers.
"The missions of Scott and Shackleton are remembered in history as heroic failures, yet the data collected by these and other explorers could profoundly change the way we view the ebb and flow of Antarctic sea ice," says lead researcher Jonathan Day, according to ScienceAlert.
Robert Falcon Scott s Pole party of his ill-fated expedition  from left to right at the Pole: Oates ...
Robert Falcon Scott's Pole party of his ill-fated expedition, from left to right at the Pole: Oates (standing), Bowers (sitting), Scott (standing in front of Union Jack flag on pole), Wilson (sitting), Evans (standing). Bowers took this photograph, using a piece of string to operate the camera shutter.
Henry Bowers (1883–1912)
Many of the logbooks have been digitalized by the International Comprehensive Ocean-Atmosphere Data Set initiative, while many of the logbooks were digitalized especially for the study. But all the information was used to create a data-set of 191 observations covering the period from 1897 to 1917.
"The study is the first to calculate sea ice in the period prior to the 1930s, and suggests the levels in the early 1900s were between 3.3 and 4.3 million square miles (5.3 and 7.4 million square kilometers)," Sarah Knapton reports for The Telegraph.
So what does this new research mean with regard to climate change? Day says the research suggests that the Antarctic's sea ice is less sensitive to global warming because it has been doing "its own thing" for 100 years.
"If ice levels were as low a century ago as estimated in this research, then a similar increase may have occurred between then and the middle of the century when previous studies suggest ice levels were far higher," Day says. And he also says we shouldn't get complacent, either.
"The Southern Ocean is largely a 'black hole' as far as historical climate change data is concerned, but future activities planned to recover data from naval and whaling ships will help us to understand past climate variations and what to expect in the future," he said.
More about Antarctic, Sea ice, Climate change, 100yearold logbooks, natural fluctuation
 
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