Shipping Logs Show How Quickly Arctic Sea Ice Is Melting

The Economist

The region is losing ice at the fastest rate since 1900

A. Schweiger et al, Journal of Climate 2019
Arctic sea ice volume variability over 1901-2010: a model-based reconstruction

Climate change is affecting all parts of the globe. But no place is feeling the heat quite like the Arctic. Although average global temperatures have risen by about 1°C since pre-industrial times, warming in the Arctic is happening two to three times as fast. The area of ice covering the Arctic ocean is at a record low, according to America’s National Snow and Ice Data Centre. Over the past 30 years, the minimum coverage of summer ice has fallen by half.

Scientists know the Arctic has less ice than it than it once did, but precise measurements are limited. Satellite images of the region, the best source of data available, go back less than 40 years. And even though they are useful for measuring the area of sea ice, they provide no information about its depth. To fill in the blanks, researchers have turned to ships’ logs from the past. Old Weather, a crowdsourcing project, has enlisted the help of thousands of volunteers to transcribe entries from 20th-century ship logbooks (some written by hand) to help scientists compile historical climate data to feed into their models.

See article at The Economist