How does Ice Pump work?
The Ice Pump is driven by the changes in water density which happen as its salinity (how salty it is) and temperature varies.
The story starts between Greenland and Iceland where warm, salty surface water brought from the Caribbean by the Gulf Stream cools to about 4°C (when water is densest) and sinks to near the bottom of the ocean where it joins the Atlantic Conveyor Current taking it south to join the deep current circling Antarctica. Some of the warm water is then drawn to Antarctica’s ice sheets by the ‘Ice Pump’ in a process that starts slowly and builds up speed. First some deep warm touch the glacier melting a little. This meltwater is less salty and so less dense causing it to flows up along the bottom of the glacier dragging more of the denser warm water under the glacier and causing more melting. This is the ‘Ice Pump’:
Source: International Thwaites Glacier Collaboration
The Ice Pump is strongest where the sea bed under the glacier slopes downwards away from the sea. This is the case for over 400 kilometers of the Thwaite’s glacier:
Comparing West Antarctica with China and South East Asia on the same scale gives an idea of the size of the problem:
For more information see the BBC’s January 2020 story about the Thwaites glacier see: www.bbc.com/news/science-environment-51097309