A Sea of Ancient Ice


Scientists dust off historical accounts to tackle a long-standing Arctic mystery.

When Harper’s Weekly magazine reported the spotting of a seven-mile-long chunk of thick sea ice off St. Johns, Newfoundland, Canada in 1884, the story referred to the prairie-sized floe as a “monster ice island” and forewarned ship captains travelling in the area: “Woe to the mail steamer that shall crash against its sides or upon its hidden base.”

This was at the tail-end of the Little Ice Age, when vast areas of the Arctic Ocean were covered by seemingly-impenetrable slabs of ice, and icebergs would stray as far south as Bermuda.

Sea ice was irrefutably thicker during the 19th and early 20th centuries than it is today—warming in the Arctic has caused much of its ancient ice to vanish—but according to WHOI climate scientist Alan Condron, the actual thickness of the legacy ice has been a long-standing mystery in climate science circles.

“While we have been able to determine the amount of sea ice extent since 1979 with satellite data, we've only had continuous satellite observations of ice thickness since the early part of this century,” says Condron. “Before that, we only have a few sporadic observations from U.S. Navy submarines taken during the Cold War in the late 1950’s. Prior to that, there is nothing.”

Continue reading at Woods Hole Oceanographic Institution

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