Scientists have pointed to the climate crisis as the likely cause for the decline of Antarctic sea ice. On 12 October, a new study revealed that more than 40% of Antarctica’s ice shelves lost volume in 25 years.
This climate-induced sea ice loss could threaten communities across the world and decimate Antarctic wildlife.
Antarctic ice shelves decimated
In a study published in the journal Science Advances on Thursday 12 October, scientists analysed more than 100,000 satellite radar images. Specifically, the researchers assessed the health of Antarctica’s 162 ice shelves.
Ice shelves are freshwater extensions of the ice sheets that cover much of Antarctica. These float on the seas that surround the vast and ecologically fragile continent. The ice shelves act as giant “plugs” by stabilising massive glaciers, and slowing down the flow of ice into the ocean. When they shrink, these plugs weaken and the rate of ice loss from the glaciers increases.
Crucially, the analysis found that the volume of 71 of these ice shelves fell from 1997 to 2021.
According to the US National Snow and Ice Data Center, in September, sea ice around Antarctica hit its lowest winter levels since records began 45 years ago.
The role of the climate crisis
As the Canary’s Tracy Keeling explained in January, scientists have been cautious to attribute the Antarctic sea ice loss to the climate crisis. This is because there are multiple factors which drive changes in sea ice extent within the region, such as wind patterns for instance.
However, as Keeling highlighted, scientists are increasingly pointing to rapid global warming as a significant contributor. Remarking on the low ice levels, Keeling reported that Penn State geoscientist Richard Alley had argued that:
the ice extent changes “must include the effects of global warming”
And the new study provides more evidence to support the role of the climate crisis in the recent deterioration of Antarctic sea ice. Notably, it found that almost all of western Antarctica’s ice shelves lost volume as they were exposed to warmer water that eroded them from below.
On the western Getz Ice Shelf alone, melting at the base was responsible for 95% of the net loss of 1.9tn tonnes of ice.
University of Leeds professor Anna Hogg who co-authored the study said that it showed:
We are seeing a steady attrition due to melting and calving… This is further evidence that Antarctica is changing because the climate is warming
Meanwhile, co-author Benjamin Davison underscored that the ice shelves’ failure to regrow after a period of shrinking also bolstered the climate case. He said that:
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.
Davison argued that without human-caused warming, some ice regrowth would have occurred on West Antarctica’s ice shelves through a natural variation in climate patterns.
Ice loss destroying Antarctic wildlife
Of course, the decline of Antarctic ice shelves could have significant ramifications for its wildlife inhabitants. A study in August found that extensive regional Antarctic ice loss had caused “catastrophic” breeding failures in four major emperor penguin colonies.
Given the devastating impact of Antarctic sea ice loss on this iconic penguin species, the new Science Advances study only makes these findings more alarming.
The new ice shelf research also comes as nations prepare to convene for the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Established in 1982, the international treaty governs the fisheries and the exploitation of resources in the region. Representatives from global nations will begin a fortnight of meetings in Australia on Monday 16 October.
Chief among the discussions will be the creation of three new Antarctic marine protected areas (MPAs). The bid to create the sanctuaries around Antarctica would safeguard nearly four million square kilometres (1.5 million square miles) of ocean from extractive human activities.
The European Union and Australia first proposed these MPAs in 2010, before scaling plans down in 2017 in an attempt to win more support.
However, China and Russia have persistently blocked the proposal, including most recently at the commission’s June meeting in Chile. Both nations have expressed concerns about compliance issues and fishing rights.
Environmental non-profit WWF has called for the commission to finally act, given the record low levels of sea-ice in the region and evidence of “mass deaths of vulnerable species.” WWF Antarctic conservation manager Emily Grilly said that:
We can’t stop all the effects of climate change in the short term, but we can take the pressure off in other ways.
Ice shelf loss risks rising sea levels
In February, United Nations (UN) secretary general Antonio Guterres warned that sea level rise threatens up to 900 million people. And in September, the leaders of nine small island states turned to a UN maritime court over the rising sea-level impacts of climate breakdown.
The Science Advances study underlines the risks that Guterres and the island leaders are warning the world about. Davison said that:
Acceleration of glaciers due to ice shelf deterioration has added about six millimetres to global sea level since the start of the study period
Although Antarctica only contributes 6% to total sea level rise, Davison argued that:
it could increase substantially in the future if ice shelves continue to deteriorate
The study’s implications for coastal communities and low-lying island states therefore hammers this point home. Ultimately, the climate crisis-exacerbated ice loss and resulting sea level rise will threaten the continent’s non-human inhabitants, as well as coastal communities across the globe. Wealthy polluting nations and corporations need to step up fast.
Feature image via W. Bulach/Wikimedia, cropped and resized to 1910 by 1000, licensed under CC SA-BY 4.0
Additional reporting via Agence France-Presse
