NASA mission uncovers hidden driver of Arctic ice melt

NASA’s most ambitious Arctic research mission yet has uncovered unexpectedly high concentrations of ice particles in clouds over Greenland, potentially explaining the region’s accelerating ice melt. The Arctic is changing at an unprecedented rate, raising concerns over the future of its fragile environment.

Patrick Taylor, deputy science lead for NASA’s Arctic Radiation Cloud Aerosol Surface Interaction Experiment (ARCSIX), told Space.com: “The Arctic is changing faster than anywhere else on the planet, so the question we're trying to ask here is: Is the Arctic going to change fast – or really fast?”

The ARCSIX mission involved a fleet of aircraft, including a NASA C-130 and a P-3 Orion, which gathered data by flying through Arctic clouds and deploying buoys into ice-laden waters. While analysis is ongoing, initial findings suggest dust from Greenland’s increasingly exposed landmass is accelerating the melting of vulnerable sea ice.

Greenland’s dust factor

Researchers suspect that as Arctic ice retreats, more of Greenland’s exposed terrain sheds dust, which is carried north by strong winds, increasing ice particles in clouds. These dust-laden clouds dissipate faster, leaving more ice exposed and intensifying the melt, said Space.com.

Linette Boisvert, ARCSIX cryosphere lead, highlighted significant ice loss north of Greenland: “The sea ice north of Greenland had a giant opening in it in the summer months. We think it’s caused by really warm, moist air being blown through Fram Strait,” a passage between Greenland and Svalbard, “up and towards the central Arctic,” she told Space.com.

Further analysis of the ARCSIX data will help determine how quickly Arctic ice is vanishing. Julia Schmale, a scientist specialising in aerosols and their impact on clouds, told the website: “That’s why these results are so important because they help quantify the amount of ice crystals, and we can start plugging that into our models to understand how clouds will change.”

With Arctic ice melting faster than projected, the findings from ARCSIX could be crucial in refining climate models and predicting the region’s future.

The aircraft operated from May to late July 2024, when seasonal sea ice melt peaked. Researchers expected to find ice roughly 3.5 metres (11.5 feet) thick but instead recorded an average thickness of just 2.2 metres (7.2 feet). Boisvert noted to Space.com: “It’s alluding to the fact that this thicker sea ice north of Greenland is not as sustainable as it once was.”

Since satellite records began in 1979, Arctic ice has diminished by around 12% per decade, equivalent to 3mn square kilometres (1.16mn square miles), an area larger than Alaska, Texas, California and Montana combined. The decline now appears to be accelerating, with ice shrinking at 12.2% per decade – six times the rate observed in the 1990s.

Tracking ice melt

NASA launched ARCSIX to assess how much longer Arctic sea ice will last. Taylor told Space.com that the mission produced “the most comprehensive set of sea ice, cloud, radiation and aerosol measurements ever collected in the Arctic.” Conducting research in such a remote area posed major logistical challenges, requiring NASA to rent extra seats on a Space Force transport plane for cargo and supplies. Christina McCluskey, a climate scientist at the National Center for Atmospheric Science, said: “I get shivers just thinking about it.”

To measure ice thickness, NASA deployed buoys fitted with thermometers in gaps between floating ice. Some were destroyed by icebergs, while others were at risk from polar bears, necessitating a white paint coating to reduce attraction. “If you make them a different colour, polar bears become attracted to them and will destroy them,” Taylor told the news site. The remaining buoys will provide long-term data, complementing aircraft observations to assess ice thickness variations.

The role of dust

Climate models rely on supercomputers to process vast amounts of atmospheric data, including cloud particles that influence ice formation. NASA scientists analysing seven years of satellite data found that dust triggered ice formation in 4.5% of clouds below 15°C (59°F), with estimated dust concentrations of 93 nanograms per cubic metre. ARCSIX data suggests these figures may be significantly higher.

“We're trying to figure out why we’re finding all this ice in the clouds,” Taylor said. “The answer could help scientists understand the pace of Arctic melt.”

Clouds reflect sunlight and slow ice melt, but ice crystals make them heavier and more likely to dissipate, exposing the ice below to direct sunlight. Ice cannot form in clouds without particles to adhere to, and dust provides this necessary nucleus.