Extended Data Fig. 1: The annual extent of sea ice in the Western Hudson Bay subpopulation region as derived from PMW data.
From: Fasting season length sets temporal limits for global polar bear persistence
Grey lines are daily extent in each year for 1979-2016 based on satellite observations. The colored curves are means of the daily extent: 1979-1988 (blue), 1989-1999 (green), 2000-2009 (yellow), and 2010-2016 (red). The thick black line is the 1979-1988 March mean extent, and the thin black line is the critical extent, taken as 30% of the 1979-1988 March mean. The first (last) day-of-the-year when the extent drops below (rises above) the critical extent in each year is marked with a magenta (turquoise) square.
