A red cascade occasionally appears to leak from Antarctica’s Taylor Glacier. Aptly named Blood Falls, the icy outflow’s striking color is caused by iron-rich brine that spews from the glacier’s side and rapidly oxidizes after hitting the air. The sight has puzzled observers since it was first spotted in 1903, but now, scientists have compiled a new historical record of brine releases to shed light on the frequency and extent of the phenomenon. The researchers presented their findings on 17 December at AGU’s Fall Meeting 2021.
“I just got to thinking, ‘Wouldn’t it be cool if we knew more about how often this waterfall feature has been active or when it’s been active?’ because it looks so bizarre,” said Chris Carr, a glaciologist at the Los Alamos National Laboratory. She led this project as part of her doctoral thesis at the University of Alaska Fairbanks.
Digging Through Archives
Taylor Glacier stretches nearly 55 kilometers (34 miles) and sits near Antarctica’s coast south of New Zealand.
Starting in 1993, researchers with the McMurdo Dry Valleys Long-Term Ecological Research Project began extensively documenting the glacier’s brine releases—currently, they collect yearly water samples and daily photos. Scientists have found evidence of Blood Falls activity during most monitored years.
To learn more about past, unmonitored events, Carr sifted through thousands of archived photographs, journals, field reports, interviews, and papers dating as far back as 1903. Many of the historical photos, however, lacked locations or years, and some even mislabeled the glacier, requiring Carr to cross-reference the information with other resources she hunted down.
“I had to start building this timeline and story of who was there [at Taylor Glacier] and start reading through these old field reports to get a sense of what projects people had going on in the area,” Carr said. “That started to make the photos fall into place.”
By not only unearthing but also substantiating these stories, Carr and colleagues discovered two unreported Blood Falls events. One was through photos captured during the 1969–1970 field season by Lois Jones, the field team leader of the first U.S. Antarctic Program expedition to include women. The other was through photos of a Japanese field party in the 1981–1982 season that Carr cross-referenced with New Zealand archives.
Assessing the Data
Creating rules to interpret these past observations in a consistent way proved challenging, Carr said, especially when she had to compare photos taken at different angles and resolutions.
She started by sifting through the photos she discovered, deciphering the best and worst depictions of Blood Falls, then organizing the rest in between. She also examined research journal entries to see if the authors noted Taylor Glacier’s discolored ice. These processes culminated in qualitative rating scales to evaluate whether dates were reliable and to rank the quality of each brine release observation.
“It was a really different way of doing science than what some of my other projects had been,” Carr said.
Contributions to the Field
In addition to discovering the two field seasons with previously unknown Blood Falls events, Carr and colleagues also found that in all, 21 of 30 documented summer seasons between 1903–1904 and 1993–1994 show signs of brine releases, and these events may have lasted weeks to months.
“It’s surprising to me how much is still unknown about a feature as charismatic and well-known as Blood Falls,” wrote limnologist Jade Lawrence of the Polar Oceans Research Group, who was not involved in this study, in an email to Eos. “Hopefully, a high-quality record of historical flow events will give us greater insight into the hydrology of brine flow throughout the 20th century.”
The resulting record isn’t yet extensive enough to answer specific questions about the timing and extent of the brine releases, Carr said, but she encourages others with historical knowledge to help fill in the gaps. The new compilation can help researchers analyze environmental changes over the past century and suggests that historical archives can be used in other scientific research to elucidate unknown or unreported events.
—McKenzie Prillaman (@meprillaman), Science Writer