Feedback loops accelerate warming, other atmospheric changes in Arctic

UNIVERSITY PARK, Pa. — The climate is changing and nowhere is it changing faster than at Earth’s poles. Researchers at Penn State have painted a comprehensive picture of the chemical processes taking place in the Arctic and found that there are multiple, separate interactions impacting the atmosphere.

Using two instrumented planes and ground-based measurements from a two-month long field campaign to compare chemical processes in two regions in the Arctic — and the largest oil field in North America — to surrounding areas, researchers made three discoveries. The findings were: openings in the sea ice — called leads – significantly influence atmospheric chemistry and cloud formation; emissions from the oil field measurably alter regional atmospheric composition; and together, these processes contribute to a feedback loop that accelerates sea-ice melt and amplifies Arctic warming.

The research was recently published in the Bulletin of the American Meteorological Society. The work was part of a larger multi-institutional project called CHemistry in the Arctic: Clouds, Halogens, and Aerosols, or CHACHA. Led by five institutions, CHACHA examines chemical changes that occur as surface air is swept into the lower atmosphere, resulting in interactions among water particles, low clouds and pollution.

“This field campaign is an unprecedented opportunity to explore chemical changes in the boundary layer — the atmospheric layer closest to the planet’s surface — and to understand how human influence is altering the climate in this important region,” said Jose D. Fuentes, professor of meteorology in the Department of Meteorology and Atmospheric Science and corresponding author of the paper. “The resulting datasets are producing an improved understanding of the interactions between sea-spray aerosols, surface-coupled clouds, oil field emissions and multiphase halogen chemistry in the new Arctic.”

To study the chemistry of the boundary layer of the Arctic, researchers sampled air over snow-covered and newly frozen sea ice in the Beaufort and Chukchi Seas, over open leads and across the snow-covered tundra of the North Slope of Alaska, including the oil and gas extraction region near Prudhoe Bay. The campaign was conducted out of Utqiaġvik, Alaska, between February 21 and April 16, 2022, shortly after the polar sunrise — a period of continuous sunlight following two months of darkness — when the increased UV rays intensify the chemical changes at the surface and in the lower atmosphere.

Researchers found that leads — ranging from a few feet to a few miles wide — created intense convective plumes and cloud formations, while lofting potentially harmful molecules, aerosol pollutants and water vapor — all things that can contribute to warming the climate — hundreds of feet into the atmosphere. These processes accelerated sea-ice loss by forcing even more convection and cloud formation, which increased moisture and heat transfer and led to the formation of even more leads, Fuentes said.

The team identified another feedback loop on land, with chemicals found in the saline snowpacks along the coast reacting with the emissions from the oil field. During the CHACHA campaign, researchers specifically observed bromine production along saline snowpacks — a phenomenon unique to polar regions. These bromine molecules rapidly depleted ozone in the boundary layer, creating another feedback loop that allows more of the sun’s rays to reach the surface, warming the snowpacks and releasing more bromine.

Additionally, during the field campaign, researchers found massive boundary layer changes over the Prudhoe Bay oil fields. Gas plumes from the extraction area reacted in the lower atmosphere, acidifying the air mass and producing harmful substances and smog, Fuentes said. They also found that halogens react with oil field plumes to create free radicals, which then form more stable substances that can travel long distances. Fuentes said these substances can contribute to regional environmental changes.

Fuentes said CHACHA researchers are now investigating how these reactions affect the broader Arctic environment, including the formation of smog plumes that, despite occurring in an otherwise pristine region, reach pollution levels comparable to those found in major urban areas such as Los Angeles. For example, nitrogen dioxide levels reached about 60-70 parts per billion, levels associated with the noxious gases blamed for urban smog.

The next steps, researchers said, involve creating datasets that numerical modelers can use to better understand how global climate may evolve as a result of these localized factors in the Arctic.

Other CHACHA team members were from Stony Brook University, the University at Albany, University of Michigan and University of Alaska Fairbanks. This research was funded by the U.S. National Science Foundation.

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