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Desert dust collected from glacial ice helps document climate change

Ohio State University researchers are using dust trapped in glacial ice in Tibet to document past changes in Earth’s complicated climate system — and perhaps one day help predict future changes.

Their results suggest that dust composition can vary widely in samples taken from different areas and depths of the same glacier, a discovery that suggests a full dust record could reveal more secrets than scientists believe.

Dust kicked up by high winds can set off a variety of chain reactions in the atmosphere, affecting everything from human health to marine biochemistry to atmospheric carbon dioxide balance. How these microparticles affect the surrounding atmosphere depends largely on their size, shape, and chemical composition.

In a new study recently published in the journal earth sciencesResearchers worked to understand how dust affects – and is affected by – climate by examining dust particles trapped in old ice, or what Emilie Beaudon, study co-author and senior research fellow at Byrd Polar and Climate Research Center, dubbed “Cryo Dust”.

“By looking at dust composition through the ice, we can gain information about the environmental state of the Earth at the time of snow deposition and ice formation,” she said. “We might be able to find out if it was a relatively dry or wet period, or try to infer where the dust originally came from, giving us information about past atmospheric influences.”

But researchers need a lot of ice to be able to collect this data.

Ice cores, ice cylinders drilled from glaciers and ice caps, have long been used as comprehensive archives of the Earth’s climate system because they are so well preserved. As layers of ice accumulate over seasons and years, aerosols accumulate in each new layer, eventually providing researchers with very detailed records of the planet’s turbulent climate history. With the help of these natural time capsules, scientists can learn what the world was like back then, including aspects such as greenhouse gas concentrations and volcanic, solar and biological activity.

The ice researchers used in this study were collected from the Guliya Ice Cap in northwestern Tibet, an area that hosts one of the largest sources of atmospheric dust in the northern hemisphere after the Sahara. Because the region is under the influence of westerly winds, much of the dust it picks up is blown toward major cities in East Asia, Beaudon said. For example, in 2021 China experienced its biggest dust storm in a decade when the storm forced entire cities to seek shelter, eventually raising concerns from the scientific community about climate change’s impact on the frequency and intensity of such events.

But scientists don’t have enough data to see how Central Asian desert dust is transported over long distances or how it changes over time. Examining a dust record from a Tibetan ice core is one of the only ways to provide a long-term perspective on the Central Asian dust cycle, Beaudon said.

In 2015, a team of researchers from the United States and China helped drill ice cores at various locations on the Guliya Ice Cap before sending those cores back to the Ohio State lab. Beaudon’s team analyzed two of the ice cores and examined the area’s dust record by examining microparticles collected on melted ice filters as well as those trapped in typical ice subsamples. Beaudon noted that the trapped dust was not uniform; Instead, each deposit was an unlikely assemblage of different colors, sizes, and strata.

“So the idea of ​​trying to determine where the dust came from came from, because there were already so many visual cues highlighting their differences,” Beaudon said.

Beaudon’s team also tried to determine if most of the particles present in the ice came from the Taklamakan Desert near the Guliya Ice Cap or if they were carried there from other distant locations.

“What we wanted to prove with these preliminary samples is that there is actual variability in their geochemistry and mineralogy,” she said. “We found that the dust doesn’t always come from the same desert, and even in the same glacier you don’t always have the same material.”

Overall, the study finds that the particularly ancient Guliya glacial dust archive is a prime candidate for deeper exploration, suggesting that Beaudon’s work, by using additional ice core samples to develop higher-resolution dust records, opens up many research avenues, including studying the microbial Populations that exist in the ice and feed on the nutrients cryodust carries.

Eventually, Beaudon envisions that her work will help examine the glacial records of planets beyond Earth. “My goal is to gain a lot of knowledge about cryodust,” she said. “If ice cores are ever drilled or samples taken from Mars or some other planet, I hope to study them.”

Additional Ohio State co-authors included Julia Sheets, Roxana Sierra-Hernández, Ellen Mosley-Thompson, and Lonnie G. Thompson. Ellen Martin from the University of Florida also contributed. This work was supported by the National Science Foundation.

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