evidence: "When polar ocean temperatures rise, then you have thinning in those ice shelves, but you can have other things occur when the ice shelves are also affected by the atmosphere," Schlegel said. "So, when you have more melting on the surface because the temperatures of the atmosphere are going up, in addition to the ocean-driven melting, then that can help create instabilities and cracks. And then you can have increased ice loss due to calving [when a portion of the ice shelf breaks away]." [...] From 2002 to 2017, ice sheets contributed a third of the total mean sea level rise, according to GRACE measurements. Over the last 25 years, Antarctic ice shelves have lost about 6,000 gigatons of ice just through thinning, researchers have found. In the long run, thinning can lead to ice-sheet collapse, Gardner said.