Arctic Meltwater Ponds Identified as Major Source of Ice-Nucleating Particles Linked to Regional Cloud Formation

CSU researchers discover that biological particles from Arctic meltwater ponds act as templates for clouds, impacting regional climate and weather models.

By: AXL Media

Published: Apr 13, 2026, 8:11 AM EDT

Source: Information for this report was sourced from EurekAlert!

Discovery of a Biological Catalyst for Arctic Clouds

New findings published in Geophysical Research Letters highlight a previously understudied mechanism of cloud formation in the Arctic’s sensitive climate. Researchers from Colorado State University have identified that "ice-nucleating particles" (INPs) originating from biological sources, such as bacteria and microbes, are being released from meltwater ponds atop sea ice. These tiny particles serve as structural templates that allow water vapor to freeze at relatively warm temperatures, facilitating the creation of clouds. Lead author Camille Mavis suggests that because the Arctic is warming four times faster than the global average, the proliferation of these ponds could significantly alter the atmospheric composition of the high North.

The Unique Composition of Sea Ice Meltwater

Unlike the open ocean, the ponds sitting on top of melting sea ice consist of a complex mixture of melted snow, seeped seawater, and released soil sediments. This environment provides a specialized habitat for small organisms and biological processes not found in typical seawater. By analyzing sea-ice core samples and surrounding aerosol emissions, the research team demonstrated that INP concentrations are notably higher in these meltwater pools than in the surrounding ocean. This suggests that the melting process itself is a primary driver for the release of these particles, rather than simple sea spray or mineral dust transported from lower latitudes.

Data Insights from the MOSAiC Expedition

The study’s data was gathered during the $150 million MOSAiC Expedition, a year-long international effort to study the decline of Arctic sea ice. Senior author Jessie Creamean traveled with the expedition to collect samples in the extreme high Arctic, an environment where gathering data is notoriously difficult. The project involved scientists from 20 nations and received major support from agencies including the National Science Foundation, NOAA, and NASA. This collaborative effort allowed the team to track how these biological particles make their way from the surface of the ice into the atmosphere, providing a rare look at real-world decision-making within the Arctic’s atmospheric system.