20%

 The ice shelf on Antarctica's Pine Island Glacier lost about one-fifth of its area from 2017 to 2020, mostly in three dramatic breaks. (Image credit: Joughin et al./Science Advances)

Global warming, the 900lb gorilla, is alive and well but we already know that, right?

Pine Island Glacier, one of the fastest-shrinking glaciers in Antarctica, hastened its slide into the sea between 2017 and 2020, when one-fifth of its associated ice shelf broke off as massive icebergs, a new study reveals.

The glacier sped up another time in recent history, between the 1990s and 2009, when warm ocean currents ate away at the underside of the ice shelf, destabilizing its structure and causing the glacier to accelerate toward open water, according to a 2010 report in the journal Geophysical Research Letters. 

(a) Modeled velocity constrained to match the 1996 (GL96) flow speed. The lower-right inset shows the grounding-line positions as observed in 1996 (cyan) and 2009 (magenta). Figure 1a shows the modeled grounding lines, which for simplicity exclude the isolated, grounded region in 2009. (b) Profiles (along black line in Figure 1a) of measured (color) and modeled flow speed (grayscale). Only the average for the three pre-retreat models constrained by the 1996 data (GL96) are shown, since they are almost identical. The GL09 curves show the different model responses to instantaneously moving the grounding line from the 1996 to 2009 position. Black bar indicates the region that ungrounded.

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