The researchers analyzed the impacts of decreased sea ice in the Amundsen Sea in West Antarctica and found the ice-free ocean surface leads to more moisture in the atmosphere and heavier snowfalls on the ice sheet, the team reported in the journal Geophysical Research Letters.

While the additional snowfall is not enough to offset the impacts of melting ice, including it in climate models may improve predictions of things like sea level rise, said Luke Trusel, assistant professor of geography at Penn State and co-author of the study.

The Antarctic ice sheet plays a significant role in global sea level dynamics. As one of the world’s largest reservoirs of freshwater, any change in its volume directly impacts sea levels. Trusel noted that while popular attention is often on visible processes like chunks of ice breaking away, or calving, and floating away as icebergs, more subtle interactions — like snowfall on the ice sheet — can be equally significant.

“For a place like Antarctica, which is just massive, the amount of snow falling on top of the ice sheet is as important or even more important than other processes like meltwater or ice breaking off,” Trusel said. “We’re tracking both snowfall and melt to understand both ends of the equation — what takes from sea level and what gets returned to the ocean. We want to know how those factors are impacting the ice sheets.”

The primary source of snowfall in Antarctica is evaporation from the surrounding oceans, with sea ice playing a pivotal role in modulating this process, according to researchers.

“Sea ice is significant,” said Jessica Kromer, a doctoral candidate at Penn State and lead author. “It reflects sunlight, aids in cooling the planet and influences interactions between the atmosphere and ocean, including oceanic evaporation. We found that precipitation varies so much year to year. In some years, precipitation can take away from sea level or lessen the impact of the ice discharged from the sheets.”

Using satellite observations and climate data, the researchers analyzed the relationship between the ocean surface, atmosphere and Antarctic ice sheet’s mass. Their findings highlighted that during periods of reduced sea ice, the atmosphere retained more moisture. This moisture, when reaching the colder ice sheet boundaries, condenses, leading to increased snowfall.

The findings, researchers said, suggest that as global temperatures inch upwards and Antarctica warms, shrinking sea ice levels will amplify oceanic evaporation and consequent precipitation over Antarctica. This increased snowfall can momentarily stave off rising sea levels. However, sea levels will still rise overall.

“With global warming, there’s an expectation of reduced sea ice,” Trusel said. “As sea ice diminishes, there could be increased evaporation from the ocean leading to more precipitation over Antarctica. While this might appear to offset the loss of sea ice, the implications are multifaceted. Increased snowfall in Antarctica might slow the sea level rise, but it’s essential to recognize that the ice sheet will continue to contribute to rising sea levels.”

The scientists identified a feedback loop between sea ice and atmospheric water vapor. A more ice-free ocean surface intensifies evaporation, contributing to increased atmospheric water vapor. This enhanced moisture causes a locally amplified greenhouse effect, resulting in heightened downward longwave radiation, which subsequently reduces sea ice the next month.

Kromer highlighted recent satellite data, which indicates notable changes in the patterns of sea ice.

“While Arctic sea ice has been rapidly declining over the satellite record, the Antarctic experienced a slight increase until 2015, followed by a sharp decline in 2016,” Kromer said. “In 2022, we witnessed a new record low, and this year’s levels are even lower, significantly below previous observations. These recent rapid changes in Antarctic sea ice highlight the urgency of understanding their causes and their potential impact on the Antarctic ice sheet.”

The team’s findings emphasize the need for refining current climate models to enhance their predictive accuracy, the scientists said.

“If we aim to project future sea level changes with precision, it’s essential to enhance our models, particularly in representing sea ice dynamics,” Trusel said.

The NASA Cryospheric Sciences Program supported this work.

In April, the Super Pressure Balloon Imaging Telescope (SuperBIT) was launched from Wānaka Airport, New Zealand, suspended under a helium-filled balloon the size of a sports stadium on top of the Earth’s atmosphere, and floated around the world 5.5 times. Unfortunately, it was damaged on landing in southern Argentina the following month.

Separately, two Data Recovery System packages storing more than 200 gigabytes of SuperBIT’s information descended by parachute and landed safely, including a map of dark matter around galaxies and stunning photos of space. Dark matter is an invisible substance that has a mass six times greater than regular matter in the universe.

A study led by Dr Ellen Sirks from the University of Sydney’s School of Physics, published today in the journal Aerospace, provides instructions to build the Data Recovery System she designed, and recounts the mission that demonstrated, for a relatively small cost, scientists can ensure the information they gather can be salvaged in the worst-case scenario.

The authors of the study, comprised of a team of international scientists from Australia, the United Kingdom, the United States, Canada, Europe and Taiwan, said that the first use of the Data Recovery System capsules during a live science mission proved a huge success.

“Our telescope got to the point where it was completely destroyed, and we lost high bandwidth communications, so not only did the Data Recovery System work; it was really quite essential to the mission’s success,” Dr Sirks said.

“When you’re dropping something from the sky, in our case from 33 kilometres, there’s always a chance that something goes wrong, so recovery packages are quite essential to keep your data safe.

“This drop package is something we’ve been developing for about five years, but only now have we been able to test it in its final configuration. It’s got to the point where NASA wants to start producing these packages for other science missions as well, so this was really our final test to show that this system works.”

Dr Sirks said Data Recovery Systems are comprised of small computers with SD cards to store the data, a home-made “find my phone” satellite link, and parachutes — housed in foam enclosures using everyday objects such as chicken roasting bags to keep them waterproof.

The story of recovering the packages itself was a mission. Dr Sirks said the local police in the Argentinian countryside helped retrieve the packages, given the rough terrain where they landed.

“We couldn’t find one at first and when we did, there were cougar tracks in the snow near it, so we thought maybe the chicken roast bag was not the best idea. It was quite funny. But we did retrieve them quite easily,” Dr Sirks said.

In a typical balloon-based mission like NASA’s, data is downloaded by satellite, but Dr Sirks said scientists often need line-of-sight communication to download the data quickly, which isn’t always efficient or possible.

Balloon-based observations also provide the quality of space telescopes at a fraction of the budget — millions of dollars compared to billions.

“In our case, we were getting so much data per night that it would just be incredibly slow and expensive to retrieve this data mid-flight,” Dr Sirks said.

“At the moment, the most efficient way for us to download data is to copy it onto an SD drive and just drop it to Earth which is kind of crazy, but it works well.”