A major glacier located in West Antarctica could, according to recent research, be near or past a tipping point, beyond which the glacier will inevitably slide into the ocean. Pine Island Glacier has had its grounding line, the area where the glacier rests either on the ocean or land, pushed back toward land due to increasingly warm ocean temperatures melting it from below. If it retreats behind a lip on the continental shelf, rapid and irreversible loss of ice will occur.
Investigation into the glacier indicates that the grounding line may have retreated behind the lip back in 1996.
Research indicates that before the next stable grounding line can be reached on the inner slope, half of the land-based glacier will have melted into the ocean. Melting land-based glaciers result in rising sea levels. Half of Pine Island Glacier would raise sea levels by 9″ before 2100. If a nearby glacier also retreats, sea levels would rise by 20″. Either case would result in the displacement of millions of people worldwide, likely leading to the collapse of stable governments.
Tipping points can no longer be viewed as future abstractions. We are already passing them, cementing disastrous events in our future. How many we pass, and by what degree, is up to us.