Sustainable Energy

Logbooks from age of exploration shed new light on size of Antarctic sea ice

The members of Captain Scott's ill-fated expedition to the South Pole, (l to r) Laurence Oates, H.R. Bowers, Robert Scott, Edward Wilson and Edgar Evans. They reached the Pole a month after Roald Amundsen's Norwegian party, but all died on the return journey.
Hulton Deutsch Collection | CORBIS | Getty Images

The intrepid, and often ill-fated, adventures of explorers such as Captain Robert Scott have gone down in folklore. Now, they have helped to inform research which suggests that the area of sea ice around the Antarctic is little changed compared to 100 years ago.

The research, published in open access journal The Cryosphere, estimates the extent of the Arctic summer sea ice is today at most 14 percent smaller than during the early 20th century.

During the 'heroic age of Antarctic exploration', a period between 1897 and 1917, explorers such as Scott – who led two expeditions to the Antarctic, the latter a fatal one – kept logbooks. Among other information, these logbooks contained "ice observations."

Climate scientists at the University of Reading, in the U.K., compared these observations of the Antarctic ice to satellite images showing its location today.

According to a news release from the university on Thursday, their study suggests that sea ice in the Antarctic is "much less sensitive to the effects of climate change than that of the Arctic." The Arctic had, by contrast, seen a "dramatic decline" during the 20th century.

"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," Jonathan Day, who led the study, said in a statement on Thursday.

"We know that sea ice in the Antarctic has increased slightly over the past 30 years, since satellite observations began," he added.

Scientists, Day explained, had been working to understand this trend in the context of global warming. The new findings, he said, suggested it "may not be anything new."

"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," he went on to explain.

The new study, according to the University of Reading, is the first to "shed light" on the extent of sea ice in the years prior to the 1930s. It pointed to sea ice levels in the 1900s being similar to today's, between 5.3 and 7.4 million square kilometers.

Other data has suggested that, during the 1950s, Antarctic sea ice was "significantly higher", after which a rapid decline put its size in recent decades at roughly 6 million square kilometers. This pointed to significant fluctuations between decades of high and low ice cover, the university said, rather than one steady decline.

"The Southern Ocean is largely a 'black hole' as far as historical climate change data is concerned," Day said. "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."