Melting Ice, Global Warming.

The polar regions are important drivers of the world's climate. When the "everlasting ice" melts at an increasing rate, the rest of the world is affected. Global sea levels are rising, dark meltwater pools absorb warmth from the sun which white ice would reflect back into space. Fresh water flows into the sea, changing ocean currents and the living conditions for marine organisms. For 20 years satellites have been monitoring earth's biggest ice shields on Greenland and in the Antarctic, using different technologies from radar to gravity measurements. In the past, the uncoordinated publication of individual one-off measurements led to confusion, especially with regard to the state of the Antarctic ice.

 A new study, supported by NASA and European Space Agency ESA combines the data from different satellite missions. Thanks to the accuracy of our data set, we are now able to say with confidence that Antarctica has lost ice for the whole of the past 20 years. In addition to the relative proportions of ice that have been lost in the northern and southern hemispheres, we can also see there's been a definitive acceleration of ice loss in last 20 years. So together Antarctica and Greenland are now contributing three times as much ice to sea levels as they were 20 years ago," says the Professor of Earth Observation. According to the study, melting ice from both poles has been responsible for a fifth of the global rise in sea levels since 1992, 11 millimeters in all.

 The rest was caused by the thermal expansion of the warming ocean, the melting of mountain glaciers, small Arctic ice caps and groundwater mining. The share of the polar ice melt, however, is rising.