In this photo captured by Ben Holt in 1987, scientist Frank Carsey drills into the sea ice. NOAA@NSIDC holds a collection of sea ice thickness measurements of the Arctic Ocean from 1879, starting with the fated Jeannette Expedition, to 2016. Learn more:
nsidc.org/data/g10011/versions/2 pic.twitter.com/KcGPoHQuMn