Figure 4a. This graph shows sea ice volume from European Space Agency (ESA) CryoSat-2 thickness for February 22, 2020. Ice volume is tracked between mid-October and mid-May. Ice volume is estimated from the NASA CryoSat-2 Sea Ice Elevation, Freeboard, and Thickness, Version 1 product (Kurtz and Harbeck, 2017). ||Credit: B. Raup, NSIDC | High-resolution image