The Arctic frequently experiences temperatures that support the formation of mixed-phase clouds that contain supercooled liquid droplets and ice crystals. The composition of such clouds plays a crucial role in the region's energy balance and climate system. Clouds with more liquid last longer and reflect more sunlight than those with more ice crystals. With Arctic warming, meteorologists have been interested in determining the effect of rising temperatures on cloud composition and its broader effect on the region. Climate models generally predict that as the Arctic warms, clouds in the region will contain more liquid water and less ice, since warmer temperatures typically suppress the formation of ice crystals. However, cloud formation is also influenced by the presence of aerosols which act as seeds, both for the condensation of liquid droplets and the formation of ice crystals. In a study published in Communications Earth & Environment, on 18 September 2024, researchers led by Associate Professor Yutaka Tobo from the National Institute of Polar Research, Japan, investigated the relationship between rising surface air temperatures and aerosols known as ice-nucleating particles (INPs), which are known to promote ice crystal formation in clouds. They found that surface warming in the Arctic leads to an increase in snow and ice-free areas, which release higher amounts of active INPs. These INPs can induce ice formation in clouds, reducing the liquid water content in mixed-phase clouds and potentially accelerating further warming. "We found that the INPs tended to increase exponentially with rising surface air temperatures when the temperatures rose above 0°C and snow/ice-free barren areas and vegetated areas appeared in Svalbard, a region experiencing warming five to seven times faster than the global average," says Associate Professor Tobo. The observations are based on year-round measurements of INPs taken during the... |