Antarctic Ice-Sheet Collapse Could Trigger Rapid Sea-Level Rise

A study published in Nature finds that Antarctic ice-sheet collapse driven by greenhouse gas emissions could double the sea-level rise predicted for this century—from 3.2 feet according to a three-year-old United Nations estimate to upward of 6.5 feet by 2100. The research builds on the work of other recent studies pointing to an irreversible melting of the West Antarctic Ice Sheet as a result of human-caused climate change, but it suggests that sea-level rise could shift into high gear, becoming anexistential problem for low-lying coastal cities within the lifespan of current generations of people absent rapid emissions cuts to contain warming to within 2 degrees Celsius above pre-industrial levels.

The study findings are based on new computer simulations showing that warming of the atmosphere and the oceans makes the ice sheetvulnerable from above and below. By the 2050s, according to the simulations, the ice sheet would begin disintegrating, and parts of the higher, colder ice sheet of the East Antarctica would also eventually fall apart.

The climate model developed by the study authors accounts for ice loss through complex processes, including “hydro fracturing,” a process whereby meltwater on ice shelves causes huge chunks of ice to fall into the water. By reflecting these processes, the researchers were able tosimulate past geological periods in which sea levels were higher than today but carbon dioxide levels were about the same or even much lower. They projected sea-level rise using versions of their model that best simulated these periods—the first model to do so.

Why is reconstruction of past rises in sea level important? High sea levels during warm intervals, such as the Pliocene and Eemian eras, imply that the Antarctic Ice Sheet is highly sensitive to climate warming.

“In the past, when global average temperatures were only —> Read More