The Arctic is heating up at an alarming rate, two to four times faster than the global average. A study by researchers from Nagoya University in Japan indicated that dust originating from snow- and ice-free areas in the Arctic could significantly impact climate change in the region.
Traditionally, it was believed that rising temperatures in the Arctic would lead to clouds with more liquid droplets and fewer ice crystals, ultimately forming thicker, more enduring clouds that reflect sunlight and cool the region in the summer (temperature feedback).
However, the recent study revealed that as temperatures in the Arctic rise, the extent of snow- and ice-free zones expands, leading to an uptick in dust emissions. This dust encourages the creation of ice crystals within the clouds. It is possible that an increase in ice crystals is causing the clouds to be less thick and shorter in duration, resulting in diminished sunlight reflection, which may raise the temperatures in the region during summer (emission feedback).
“Increasing amounts of dust due to Arctic warming may cause the opposite phenomenon of the conventional understanding of ice crystal changes,” said Associate Professor Hitoshi Matsui of Nagoya University, the lead author of the study. “Our previous study found that a large amount of Arctic dust is distributed in the lower troposphere (below about 3 km altitude) over the region in summer and early fall, with the dust acting as a very efficient nucleus for ice formation in clouds at this altitude during the season.”
To understand the influence of Arctic dust on regional cloud formations, Matsui and Dr. Kei Kawai from Nagoya University have joined forces with experts from the National Institute of Polar Research and Hokkaido University to conduct a groundbreaking study utilizing the CAM-ATRAS global aerosol-climate model.
Their research examined the changes in dust emissions from the Arctic land surface over the past 40 years, specifically from 1981 to 2020. The findings revealed a significant 20% increase in dust emissions during this timeframe, correlating with rising Arctic temperatures. This surge in dust levels enhances ice nucleation in clouds within the lower troposphere, reducing the capacity of these clouds to hold liquid droplets while increasing ice crystals.
As the Arctic continues to warm, the amplified dust concentrations favor ice crystal development, overshadowing the temperature-induced decrease in ice crystal formation in 30% of the region annually and a striking 70% during the summer months.
“Most climate models have not considered the effects of dust from the Arctic land surface,” Matsui said. “Our research suggests that the counterbalancing temperature and emission feedbacks should be considered to improve the accuracy of climate change predictions in the Arctic.”
Journal reference:
- Hitoshi Matsui, Kei Kawai, Yutaka Tobo, Yoshinori Iizuka & Sumito Matoba. Increasing Arctic dust suppresses the reduction of ice nucleation in the Arctic lower troposphere by warming. npj Climate and Atmospheric Science, 2024; DOI: 10.1038/s41612-024-00811-1