Antarctica and cover an area equivalent to the size of Greenland. The findings are part of the first-ever study of changes in the thickness of Antarctic ice shelves – extensions of land ice that float on the ocean – dating back to 1973. Previous observations date back only to 1992.

Researchers from the University of Edinburgh used satellite images from the 50-year archive of the NASA/United States Geographical Survey (USGS) Landsat program to track variations in the appearance of points on the ice surface.

Anchor points are formed when a portion of a floating ice sheet becomes anchored to a ridge on the ocean floor , creating a visible bump on the otherwise smooth surface of the ice shelf. (University of Edinburgh, more at phys.org)