CWU ice core study

Central Washington University researchers have been able to reconstruct black carbon concentrations in the atmosphere spanning the period 1840-1991 by studying ice cores in the South Cascade Glacier.

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Using ice core samples retrieved from the South Cascade Glacier, Central Washington University researchers have been able to reconstruct black carbon concentrations in the atmosphere spanning the period 1840-1991, according to a news release from CWU.

Ice cores provide invaluable information that is used to determine past climate and environmental conditions.

“This is only the second study to publish a deep ice core record from the lower 48 states,” said Susan Kaspari, CWU geological sciences professor, who led the research. “It’s unusual to get valuable environmental records from glaciers that are low elevation, but the black carbon record is less affected by melt, so the record stayed well preserved. We were also really lucky to be able to date the core well. One of the ways we dated the ice core was from an ash horizon from the 1980 Mt. St. Helens eruption.”

Black carbon, also referred to as soot, comes from gas and diesel engines, coal-fired power plants, wildfires, and other sources. It’s a major component of air pollution and an important contributor to climate change.

Kaspari and her team found that black carbon concentrations were highest during the period 1940-1960 when black carbon was 16 times higher than during pre-industrial times. The dramatic increase is attributed to domestic coal burning and forest fire emissions during those two-decades.

Interestingly, the South Cascade ice core showed the period of peak black carbon concentrations in Washington was later than other regions that industrialized earlier, such as the United States’ East Coast and Europe due to the relatively small population in the Evergreen State before World War II.

The ice core from the South Cascade Glacier, a small valley glacier in the North Cascades Range, was collected by United States Geological Survey scientists in 1994 and was stored at the National Ice Core Laboratory until 2013 when Kaspari and her team gained access to it.

“We’re also using the ice core record to tell us about the factors contributing to glacier and snowmelt in the region,” she pointed. “When black carbon is deposited on snow and glacier surfaces, it darkens the surface and causes more energy from the sun to be absorbed, leading to faster melt.”

The CWU research is gaining national attention. It was published in the June 16 issue of the Journal of Geophysical Research Atmospheres. (https://agupubs.onlinelibrary.wiley.com/doi/abs/10. 1029/2019JD031126).

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