Antarctica

Topographic map of Antarctica's bedrock.

     Antarctica holds almost 90% of the ice on Earth, about 8% in West Antarctica (including 1% in the Antarctic Peninsula) and fully 80% in East Antarctica (in the right half of circle below).  West Antarctica's ice, if melted, would raise sea level ~5 meters (16 feet).  If all of East Antarctica's ice melted, it would raise sea level another ~55 meters (180 feet).  Until 40 million years ago, Antarctica had no ice and sea levels were far higher than now.

     Glaciation in Antarctica began 39 million years (MY) ago.  It was largely complete by 34 MY ago.  Antarctic ice has waxed and waned some since then, but has been generally similar to the amount today.

    In recent years, ice shelf breakup has concentrated on the Antarctic Peninsula (upper left).  But ice loss from retreating glaciers in West Antarctica (in left half of circle) has begun.

     Roughly 2/3 of West Antarctica's ice is grounded below sea level.  But so is some 1/3 of East Antarctica’s, more than half in the Wilkes and Aurora Basins (“southeast” quadrant), toward Australia and New Zealand.  That’s more square miles in the East than the West.

     Map by Paul V. Heinrich, data from BEDMAP Consortium (European Ice Sheet Modelling Initiative, Scientific Committee on Antarctic Research)

Areas of glacier retreat (red arrows) and advance (blue)

Mapping Tipping Risks from Antarctic Ice Basins under Global Warming 0326.rtf

Below, deep red indicates the soonest eareas to melt, while tan and light tan indicate much later melting, when global temperatures reach 8 to 10°C (from immediately pre-industrial).  Ross East (Byrd) lasts the longest.

     On the speed of sea level rise (SLR) from great glacier melting, seas rose 30 meters in 900 years during meltwater Pulse 1A, from 14,700 to 13,800 years ago, coming out of the Last Glacial Maximum (LGM).  That's 3.3 meters per century.  [See Post-Glacial Sea Level Rise diagram by Robert Rhode.]

     They rose another 60 meters over 11,000 to 7,600 years ago, exiting further from the LGM.  That's 1.8 meters per century.

     The 2013-21 rate of SLR was 4.4 mm per year, doubling per 20 years.  [See Sea Level Rise Acceleration 0922.rtf - by John Englander.]  That suggests the current rate may be 6 to 7 mm per year, or 0.6 to 0.7 meters per century.

     Since the rate of warming now is faster than it was 1,000s of years ago, lag effects may be important for SLR, especially since most SLR so far has been from thermal expansion of oceans, melting glaciers not in Greenland or Antarctica, and groundwater loss to oceans.

A spectacular 4-minute video of a calving event for ice the area of Manhattan, but taller.

Areas of glacier retreat (red arrows) and advance (blue)

Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues about Future Sea Level Rise 0520.rtf

Section Map: Ice