Satellites shed light on global warming   Sea ice in Nares Strait between Greenland and Canada from 20 January to 24 March 2007.   Envisat's ASAR image, acquired on 22 March 2007, of Larsen-B Ice Shelf with previous ice boundaries at different dates between 1992 and 2002. The ice boundaries were derived from ERS SAR and Envisat's ASAR images.   Altimetry-derived mean dynamic topography of the sea surface. This is the mean height of the sea surface relative to the geoid, or the theoretical surface of equal gravity around Earth.   This animation shows the steps from top of atmosphere level-1 B data via atmospheric corrected surface reflectances, to concentration maps of phytoplankton chlorophyll, to suspended matter and the absorption coefficient of dissolved organic matter.   Four years of Sea Surface Temperature (SST) from Envisat Release date: 28 February 2012