Sara Moore
Science Editor
The 44th annual Osgood Lecture was held on Thursday, Feb. 19 in Lean Lecture Hall. This lecture series, presented by the Department of Earth Sciences, welcomes well-known scholars in the fields of paleontology or stratigraphy to share their research with students and faculty. Nicolás Young, a 2005 graduate of the College and associate research professor at Lamont-Doherty Earth Observatory (LDEO) of Columbia University, presented this year’s talk. His lecture was titled “Disappearance of North Atlantic ice sheets over the last 2.6 million years” and centered on his unpublished research conducted in Greenland and Canada. The lecture was preceded by a dessert reception sponsored by the Climate Studies program.
Young began his talk by saying much of his work is novel and still unpublished, joking that ChatGPT would currently be unable to explain it better than him. His team has been doing research since 2022 and the results are now able to be shared with the public. His research focuses on the Greenland ice sheet, specifically Prodhoe Dome, and the Laurentide ice sheet, which once covered parts of North America (including Wooster) during the last glacial maximum 25,0000 years ago. Today, all that remains of the Laurentide ice sheet is the Barnes Ice Cap which is located on Baffin Island in northern Canada. Unlike most paleoclimatologists, Young’s team did not collect the ice from these ice sheets. Instead, they drilled past the ice to collect the bedrock underneath. The chemical composition of the bedrock indicates how long the rock has been covered by ice and when the last melting period occurred.
The Earth’s current geological epoch is the holocene, which is known as the “age of humans” and marked a warming period of the climate. The Earth is experiencing natural warming as well as unnatural warming due to human activity. As a result of this warming, ice sheets are melting, making the bedrock underneath more accessible. Young used cosmogenic nuclide exposure dating, which measures the age of the ice and determines when the bedrock was last exposed based on the isotopic composition. As cosmic rays enter the atmosphere, they collide with other particles to create neutrons and muons which smash into the Earth’s surface, producing many different elements in the form of isotopes within the rock. Scientists calculate the concentration of these isotopes in the rock to determine how many years ago the rock was exposed to the sky and, in turn, the age of the ice. The two most common isotopes they use are beryllium-10 (10Be) and aluminum-26 (26Al) as they have very long half lives at 1.4 million years and 700,000 years, respectively. Once the rock is covered in ice, no more isotopes are formed, so they can determine the age of the ice based on the amount of 10Be and 26Al remaining in the bedrock.
The data was originally collected in the 1990s in Greenland, but the technology did not yet exist to study the isotopes within the samples without destroying them. The samples were finally able to be tested in 2015. Once they ran the tests, they had to combine the mathematical results with the geological records in order to determine a possible timeline for ice coverage. Based on this data, the scientists concluded that the Greenland ice sheet likely did not disappear in the last one million years, meaning it began melting long ago. Young’s team began collecting samples from the Barnes Ice Cap in 2022. The Barnes Ice Cap is unique because there are some areas of bedrock that were uncovered 3,500-4,000 years ago and other areas where the ice began to recede in the 1960s. Based on the information gained from cosmogenic nuclide exposure dating, they determined that the Barnes Ice Cap has not been as small as it is now for at least 2.6 million years.
This work was part of the GreenDrill project, funded by the National Science Fund (NSF), which extracted ice cores and bedrock to determine the vulnerability of the ice sheets and the possibility of sea level rising in the current warming climate. This will allow scientists to determine how changes to the ice have impacted Earth in the past and what the possible impacts will be in the coming centuries. Ice cores were collected from two different locations and are now being studied to determine what can be learned about the future from the Earth’s past.
Young’s research was popular among attendees, especially those in the earth sciences field. Lauren Segura ’26 said, “I thought it was great. It’s a lot of new research, which is really cool to hear, especially around a topic that’s so relevant right now.” Cheyenne Wentz ’27 shared this sentiment, “It was really awesome. I might do something with glaciers for my [Independent Study] so I’m really interested in, like, glaciers and ice. I just wanted to see what’s happening in the professional world.” When asked about the selection process for the Osgood Lecture, Meagen Pollock, chair of the earth sciences department, said, “[Young] is an alum of the College and the department, so we’re delighted to invite our alumni back to campus. And the work that he’s doing is really at the cutting edge of … climate research and understanding what’s happening to our ice sheets today and how they’ve changed in the past and how that could inform what they’re [going to] look like in the future.”
For more information about Young’s research, please visit https://cosmo.ldeo.columbia.edu/people/nicolas-e-young
