This NASA satellite image from January 31, 2018, shows the western half of the Bering Sea free of ice, part of a historic record-low winter ice extent (graph at lower left) across the region. Compared to ice-covered areas, open water absorbs significantly more incoming sunlight, creating a feedback loop in which warming causes loss of sea ice, which causes more warming. NOAA Climate.gov image based on Worldview imagery and data provided by Rick Thoman.