Analysis Of 110 Years Of Mariners' Logs In Arctic Shows "Nothing Remotely Like Last 40 Years"
Last edited Sun Aug 11, 2019, 01:13 PM - Edit history (1)
A 19th-century polar explorer depicted the harrows of traversing the Arctic, "for its course is tracked with hardships, and its field is sown with graves." The often-frigid, ice-clad Arctic remains a harsh world. But in the early 1900s, there was substantially more ice than there is today. New research used old shipping logs, meticulously kept by mariners often each hour, to extend the Arctic sea ice record back 110 years, over seven decades before satellites began regularly monitoring the high north.
Back then, sea ice showed a lot of variability, with an overall decline between 1901 through 1940. But that decline pales when compared with the Arctic's plummeting sea ice thickness and extent over the last four decades. "There is nothing even remotely like [the last 40 years]," noted Axel Schweiger, a sea ice scientist at the University of Washington and a lead author of the research.
The Arctic is the fastest warming region on Earth. The 12 lowest sea ice extents in the satellite record have all happened the last 12 years. This year, sea ice has either been at record lows or been flirting with record lows all summer.
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In the early 1900s, U.S. mariners logged their location using a navigational instrument called a sextant, and regularly documented sea ice encounters with notes like "steering various courses and speeds" (to avoid collisions). The logbooks, kept at the National Archives in Washington, D.C., were transcribed and digitized by citizen scientists, making the data available for research. "This is a very valuable contribution to our understanding of Arctic sea ice variability since the early 20th century," said Zack Labe, a climate scientist and PhD candidate at the University of California. "The UW study adds to the growing body of evidence that the current rate of sea ice decline is unprecedented since at least the early 20th century."
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https://mashable.com/article/arctic-melting-ship-logs/