Monday, July 18, 2016

Reconstructing Arctic History

Reconstructing Arctic History | CIRES 
  There's little doubt that Arctic sea ice is shrinking, but a new study looking back to the 1850s reveals that today's ice loss is unprecedented in extent and rate. To understand what’s happening with the Arctic ice pack, scientists need access to as much data as they can get their hands on. But reliable satellite data on the frozen north extends back only to 1978 and most historical sources cover only the twentieth century. John Walsh, Chief Scientist at the International Arctic Research Center with the University of Alaska Fairbanks, knew they could do better. “We knew there was useful information out there that goes back into the 1800s,” he says. “We wanted to provide some benchmarks so we could place the retreat we’ve seen in Arctic sea ice in a longer context.”   Other scientists wanted to do the same. Walsh heard from climate change modelers who needed more information to reconstruct the Arctic’s atmospheric history. So, Walsh went to NOAA with a proposition: To make a data product that could be used by modelers to characterize sea ice back to 1850. And a natural partner for building this database was the National Snow and Ice Data Center (NSIDC), part of CIRES, where a small team funded by NOAA was already experienced in using data from sources such as the military and old charts and maps to create a more robust picture. The final product, “Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward," is described in a paper out in the July issue of Geographical Review.      This data set expands on an earlier product that begins in 1901. “We wanted to extend and improve on the data we already had,” says CIRES' Florence Fetterer, the NOAA liaison at NSIDC. “So we gathered historical sources of sea ice information and filled spatial and temporal gaps using an analog method.” More