CRBC News
Politics
Conflict
Security
Economy
Science
Technology
Environment
Health
Culture
Society
Lifestyle
Science

Antarctic Clouds Lack the Particles That Seed Ice — A Cooling Shield Under Threat

08:54 PM, 12/03/2025
Antarctic Clouds Lack the Particles That Seed Ice — A Cooling Shield Under Threat

Air filter samples from three Antarctic stations reveal unusually low concentrations of ice‑nucleating particles (INPs) over the Southern Ocean. Low INP levels allow more cloud water to remain as supercooled liquid, making Antarctic clouds highly reflective and helping cool the Southern Hemisphere. Scientists warn that glacier retreat and increased biological activity from warming could raise INP levels, reduce cloud reflectivity and amplify regional warming. The study appears in Geophysical Research Letters and calls for more sampling to confirm continent‑wide trends.

New research shows that clouds over the Southern Ocean and parts of Antarctica contain unexpectedly low concentrations of microscopic ice‑nucleating particles (INPs) — the airborne seeds on which ice crystals form.

Ice crystals in many clouds form when supercooled liquid water freezes onto tiny INPs such as mineral dust, wind‑blown soil, volcanic ash, sea spray and biological materials (for example, proteins released by organisms). When INP concentrations are low, clouds retain more liquid water in a supercooled state and reflect more incoming sunlight than ice‑rich clouds do.

What the researchers did

Atmospheric scientists analyzed a long series of air filter samples collected at three Antarctic research stations. According to lead author Heike Wex of the Leibniz Institute, these samples represent one of the most extended mainland Antarctic datasets for INP measurements to date. The team found especially low INP concentrations at the two southernmost stations and suggest that similarly low levels may occur across other Antarctic regions, though additional sampling is needed to confirm the continent‑wide picture.

“We suggest that [the] low abundance may be due to an absence of efficient biological sources,” Wex and colleagues write, noting the contrast with regions like the summertime Arctic where biological activity supplies many INPs.

Climate implications

Because low INP levels favor liquid, supercooled clouds, Antarctic skies tend to host clouds that are particularly reflective. Those clouds help limit solar heating of the Southern Hemisphere. Tropospheric scientist Silvia Henning (Leibniz Institute) warns that this protective effect could weaken if climate warming increases INP supply.

As glaciers retreat and new land is exposed, biological activity could intensify and generate more INPs. More ice nuclei in the atmosphere would promote ice formation in clouds, lower cloud reflectivity, and could amplify regional warming through a positive feedback loop.

The study is published in Geophysical Research Letters. The authors emphasize both the significance of the findings for regional climate and the need for broader sampling to track potential changes over time.

Similar Articles

Trending