Ice melted from Greenland Antarctica in past 20 years? >4 trillion tonnes.

Guardian: The research that unearthed this fact “involved dozens of scientists and 10 satellite missions and presents a disturbing picture of the impact of recent warming at the poles. The scientists claim the study, published in the journal Science, ends a long-running debate over whether the vast ice sheet covering the Antarctic continent is losing or gaining mass.” “East Antarctica is gaining some ice, the satellite data shows, but west Antarctica and the Antarctic peninsula is losing twice as much, meaning overall the sheet is melting. ….The study shows the melting of the two giant ice sheets has caused the seas to rise by more than 11mm in 20 years. It also found Greenland is losing ice mass at five times the rate of the early 1990s. ….The study combined satellite measurements of the ice caps’ heights from laser and radar instruments with measurements of the small changes in gravity caused by ice loss. ….The 11mm sea level rise caused by melting in Greenland and Antarctica makes up about a fifth of the total rise in the oceans since 1992, but the increasing rate of melting means the ice caps’ contribution today is about two-fifths.”