Antarctic Ice Loss Is Significant, Contrary to Claims

SciCheck Digest

Antarctica is losing ice mass to the ocean, contributing to global sea level rise. But a popular video misrepresented work focused on Antarctic ice shelves — which float in the sea at the edges of the continent — to incorrectly suggest that “it is unclear if Antarctica is losing any ice on balance.”

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The Antarctic ice sheet is a vast mass of ice, accumulated over millennia via snowfall, that sits atop bedrock, covering nearly all of Antarctica. As the ice spreads outward and meets the ocean, some of it begins to float. These floating ice platforms, which surround about three-quarters of Antarctica, are called ice shelves.

Antarctic land ice loss into the ocean is an increasingly important contributor to global sea level rise. In contrast, ice shelf loss doesn’t directly cause sea level rise, as the ice is already floating in the ocean and displacing water. However, ice shelf changes can contribute to land ice loss, as ice shelves in some areas buttress land ice and slow its descent into the ocean.

A popular video from the Heartland Institute — which has a long history of casting doubt on climate science — minimized the significance of Antarctic ice loss and then questioned whether it’s happening at all. “The truth is, it is unclear if Antarctica is losing any ice on balance or if it’s currently experiencing a net gain,” the video’s narrator inaccurately said, citing two scientific papers.

“The statement is false,” Chad Greene, a glaciologist at NASA’s Jet Propulsion Laboratory, told us in an email. “Antarctica has been losing sea ice, grounded ice, and floating ice shelf mass over the past few decades. Satellite analysis from NASA groups show trends of ice loss, and the same trends have been reported by independent research groups from around the world.”

We reached out to the Heartland Institute with questions about the video but have not gotten a reply. The video was originally posted on Facebook and YouTube but is no longer available on Facebook.

The first paper mentioned in the video to back up the claim is a 2015 study by NASA researchers. They found that from 1992 to 2001 and 2003 to 2008, Antarctica gained ice mass. 

But other studies disagree with the finding that Antarctica was gaining ice, and a NASA press release about the study now contains a message saying, “The findings reported here conflict with over a decade of other measurements, including previous NASA studies.”

“[M]ore recent work shows clearly that on balance Antarctica is losing mass,” Jonathan Kingslake, who studies ice sheet evolution at Columbia Climate School’s Lamont-Doherty Earth Observatory, told us in an email. 

According to measurements from NASA satellites, since 2002 Antarctica has been losing an average of 140 billion metric tons of ice mass per year.

An ice shelf at the edge of the Antarctic Peninsula. Photo by Daniel / stock.adobe.com

The Heartland Institute video went on to incorrectly state that a 2023 paper looking at data from 2009 to 2019 confirmed the 2015 NASA findings. However, that paper looked at Antarctic ice shelf area — the floating ice at the edges of the continent, as we explained — and not ice sheet mass overall. Saying that the 2023 paper confirmed the earlier NASA findings “is totally misleading,” Kingslake said.

Additionally, data from a longer time frame does show loss of Antarctic ice shelf area, Greene said.

The Sixth Assessment Report from the Intergovernmental Panel on Climate Change — the latest report from this United Nations body — found that both the Greenland and the Antarctic ice sheets have been “losing mass since at least 1990, with the highest loss rate during 2010–2019” — a statement made with “high confidence.” And the ice sheet mass loss is expected to continue.

Antarctic Ice Loss Is Consequential

Earlier in the Heartland Institute video, the narrator did acknowledge Antarctic ice loss but minimized its importance.

“The media claims that Antarctica is losing ice six or more times faster than it was a few decades ago,” the video said. “But Antarctica was barely losing ice back then and it still is barely losing ice compared to its overall ice mass. Some satellite measurements estimate that the total ice loss each year from Antarctica is 3/10,000 of 1% of the continent’s ice mass. That’s not much.”

Media outlets have reported, based on various studies, that the Antarctic ice sheet as of the 2010s was melting six times faster than in the 1980s, or that the Antarctic and Greenland ice sheets combined were losing ice six times faster in the 2010s than in the 1990s.

It’s correct that Antarctica “is barely losing ice compared to its overall ice mass,” as the video said, given that Antarctica’s total ice mass is very large, Helen Amanda Fricker, a professor at UC San Diego’s Scripps Institution of Oceanography, told us in a written response to our questions. But “I would turn this around and say that even a small % of a large number is not inconsequential,” she said. The Antarctic ice sheet contains enough ice — if it all melted — to raise sea level by 57 meters, or 187 feet, she said.

Oceanographer Laurence Padman, president and senior scientist at Earth and Space Research, a nonprofit research institute, told us that he couldn’t argue with the fraction of ice lost given in the video, based on rough calculations and given variation and uncertainties in annual ice loss. But “the important number is the sea level rise, not the fraction of the Antarctic ice sheet that is lost,” he said in a written response to our questions.

As of 2018, the global average sea level had risen by 7 to 15 centimeters (almost 3 to 6 inches) since 1971, according to the latest IPCC report, and was projected to rise by 10 to 25 centimeters (about 4 to 10 inches) more by 2050, even if greenhouse gas emissions are reduced. Melting of the Antarctic ice sheet caused 7% of sea level rise between 1971 and 2018, but its contribution to sea level rise has increased and will continue to increase.

Since 2016, the Antarctic ice sheet has been responsible for 14% of sea level rise, according to the IPCC report. In a low-emissions scenario, the Antarctic ice sheet could contribute to more than 20% of sea level rise by 2100, according to a graphic in the report’s FAQ section.

Lizz Ultee, a glaciologist at Middlebury College, explained that sea level rise is driven by two main processes: ocean water expansion as it gets warmer and melting of ice into the ocean. 

Mountain glaciers melt more quickly due to warming temperatures than ice sheets because mountain glaciers are smaller, Ultee explained. But the Greenland and Antarctic ice sheets are playing an increasing role in sea level rise.

Currently, Greenland, which has a smaller ice sheet than Antarctica, is losing ice mass at a faster rate, but in the long term, Antarctica “has the most potential to contribute to very large sea level changes,” Ultee said. 

Antarctic ice sheet loss will probably lead to up to about 0.3 meters, or nearly 1 foot, of sea level rise by 2100, she said, and total sea level rise could be about half a meter to a meter (1.6 to 3.3 feet) by that time. Even if humans were to stop contributing to climate change by 2100, she said, Antarctica would continue to lose ice mass and contribute to sea level rise for centuries.

About a meter of sea level rise in 2100 would flood the homes of about 4 million people in the U.S., Ultee said, an estimate that doesn’t include people who would be at risk from higher storm surges or more frequent tidal flooding, or who would be cut off from essential services.

The Eastern Gulf of Mexico — from the Mississippi Delta to Florida — has already experienced some of the fastest rates of local sea level rise in the U.S., according to the National Oceanic and Atmospheric Administration.

The Important Role of Ice Shelves

As we’ve said, the Heartland Institute video also misrepresented data on ice shelves, incorrectly claiming a 2023 paper confirmed that the Antarctic ice sheet is gaining mass.

The 2023 paper, published in the Cryosphere, used satellite data to analyze the area of Antarctic ice shelves between 2009 and 2019, finding that 16 ice shelves grew in area and 18 got smaller. This translated to a net gain of 5,305 square kilometers in total ice shelf area, representing an increase of 0.4%. 

But “this paper is about Antarctic ice shelves, which are only the floating portions of the ice in Antarctica,” Ultee said. Ice shelves are made up of ice that has flowed from the continent outward to the ocean and is floating. (Sea ice, which forms seasonally from the ocean and also floats, is distinct from ice shelves.)

Antarctic ice shelves, in white, are seen at the edge of the continent, which is largely covered in the ice sheet (grey). Credit: Agnieszka Gautier, National Snow and Ice Data Center

The work “does not support the assertion that the Antarctic ice sheet is not losing mass,” Ultee said.

Padman also said that the Cryosphere paper looked at one specific time period that doesn’t represent the full history of Antarctic ice shelf loss. Prior work, published in Nature in 2022, showed that Antarctic ice shelves lost 35,000 square kilometers of area between 1997 and 2004. The Cryosphere paper showed the ice shelves regaining “only about 15% of the earlier loss,” he said.

Greene, the NASA scientist, co-authored the Nature paper. In that study, “we used a longer, 24 year baseline and found overwhelming loss of ice shelf area since 1997,” he said. “We then looked at the calving history of the biggest ice shelves and found that they are all on track for major calving events in the next 10 or 15 years … meaning Antarctica as a whole is losing ice shelf mass overall.” (Ice shelf calving occurs when chunks of ice break off into the ocean.)

Additionally, ice shelf loss in specific areas is significant and indirectly influences sea level rise, experts told us.

“Ice shelves don’t directly contribute to sea level rise when they melt but rather, they act like buttresses to glaciers, keeping the ice from simply sliding into the ocean,” Greene said.

Padman added that “some areas of ice shelves affect ‘buttressing’ of grounded ice, while other areas don’t.” The ice shelves shown to be losing ice in the Cryosphere paper — many in West Antarctica — tend to be more important for buttressing the ice sheet than the ice shelves that are gaining ice.

“Even if East Antarctic ice shelves are gaining area and the West Antarctic is losing area, we still really care about the West Antarctic ice shelf area,” Ultee said.