“Scientists track ‘alarming’ melt in Antarctic ice shelves”
“Forty percent of Antarctica’s ice shelves are shrinking, worrying scientists”
“We expected most ice shelves to go through cycles of rapid, but short-lived shrinking, then to regrow slowly. Instead, we see that almost half of them are shrinking with no sign of recovery,” said lead author Benjamin Davison, research fellow at the University of Leeds.
“Acceleration of glaciers due to ice shelf deterioration has added about six millimetres to global sea level since the start of the study period,” said Davison. “The ocean absorbs a lot of atmospheric heat and carbon and the Southern Ocean surrounding Antarctica is the largest contributor to that, so it’s a hugely important regulator of global climate.”
“We are seeing a steady attrition due to melting and calving… This is further evidence that Antarctica is changing because the climate is warming,” Anna Hogg, a University of Leeds professor who co-authored the study, said.
The study Annual mass budget of Antarctic ice shelves from 1997 to 2021 concludes:
We show that Antarctic ice shelves have exported 67,000 ± 3200 Gt of freshwater to the Southern Ocean from 1997 to 2021, of which solid ice (calving) provided 60% and which has been fairly constant on annual timescales since 1997 other than spikes in solid ice export from large calving events. These spatially and temporally resolved freshwater flux estimates could be used to inform modeling investigations seeking to constrain any emerging impacts of Antarctic freshwater export on Southern Ocean circulation, iogeochemical cycling, and ecological productivity, compared to other observationally constrained climate forcings, such as changes in sea ice extent and formation rates.
Building on previous studies (7, 45), we show that many Antarctic ice shelves deteriorated significantly from 1997 to 2021 and that the vast majority of those have significant mass loss trends. Pan-Antarctic ice shelf mass decreased overall by 7500 ± 1500 Gt during the 1997–2021 period due to both terminus retreat (6200 ± 700 Gt) and basal melt–induced thinning (4480 ± 1420 Gt), which were partially offset by increases in grounding line discharge (1770 ± 870 Gt), SMB (340 ± 90 Gt), and grounding line retreat (1070 ± 170 Gt). Ice shelf mass loss was regionally concentrated along the Antarctic Peninsula, the Amundsen Sea, and Bellingshausen Sea coastlines in West Antarctica, and in Wilkes Land and Victoria Land in East Antarctica. Pan-Antarctic ice shelf mass has increased since 2002 due to the steady advance of a small number of large ice shelves, but this growth masks significant and sustained reductions in the mass of many Antarctic ice shelves. Basal melt–induced thinning was the dominant mass loss term for a slight majority (52 to 73%) of ice shelves that lost mass. Both basal melt–induced thinning and retreat were significantly positively correlated with grounding line discharge change at many ice shelves, but there was a wide range in the strength and form of the relationship between ice shelves. These new observations provide a more detailed picture of the health of Antarctic ice shelves and drivers of ice shelf mass change than was previously available and highlight the wide-ranging relationships between ice shelf mass change and grounding line discharge change.
Also see:
Climate Change: Rate of Acceleration Brouse and Mukherjee (2023)
Sea-level Rise Mukherjee and Brouse (2022 and 2023)
Climate Change: How Long Is “Ever”? Brouse (2023)