Stability Check on Antarctica Reveals High Risk for Long-Term Sea-Level Risehttps://phys.org/news/2020-09-stability-antarctica-reveals-high-long-term.ampThe warmer it gets, the faster Antarctica loses ice - and much of it will then be gone forever. Consequences for the world's coastal cities and cultural heritage sites would be detrimental, from London to Mumbai, and from New York to Shanghai. That's what a team of researchers from the Potsdam Institute for Climate Impact Research, Potsdam University and New York's Columbia University has found out in their new study, published in
Nature (cover story), on how much warming the Antarctic Ice Sheet can survive.
... "As the surrounding ocean water and atmosphere warm due to human greenhouse-gas emissions, the white cap on the South Pole loses mass and eventually becomes unstable. Because of its sheer magnitude, Antarctica's potential for sea-level contribution is enormous: We find that already at 2 degrees of warming, melting and the accelerated ice flow into the ocean will, eventually, entail 2.5 meters of global sea level rise just from Antarctica alone. At 4 degrees, it will be 6.5 meters and at 6 degrees almost 12 meters if these temperature levels would be sustained long enough."
Long-term change: it's not rapid, but it's forever"Antarctica is basically our ultimate heritage from an earlier time in Earth's history. It's been around for roughly 34 million years. Now, our simulations show that once it's melted, it does not regrow to its initial state even if temperatures eventually sink again. Indeed, temperatures would have to go back to pre-industrial levels to allow its full recovery—a highly unlikely scenario. In other words: What we lose of Antarctica now is lost forever."
The animation shows the modelled long-term evolution of the Antarctic Ice Sheet under steadily increasing temperatures.
The upper panel shows the ice sheet's surface elevation change (in meters; grey shading), the ocean-induced melting at the base of the floating ice shelves (in meters per year; purple-orange shading), as well as the topography of the bed underneath the ice sheet and the surrounding ocean (in meters above the present-day sea level; blue-brown shading).
The lower panel shows the total sea-level relevant ice volume change (in meters of sea-level equivalent ; blue curve) and total ice mass flux (in gigatons per year; purple curve).The hysteresis of the Antarctic Ice Sheet,
Nature (2020).
https://www.nature.com/articles/s41586-020-2727-5