2023 was the hottest year on record, and for the first time, the global average temperature briefly breached 2 degrees Celsius above pre-industrial levels – a temperature that has not been sustained on Earth in over two million years. The steadily increasing global temperatures are ushering in the rapid loss of Arctic summer sea ice, which is expected to be completely gone in less than two decades and, as the most recent International Cryosphere Climate Initiative Report says, “We cannot negotiate with the melting point of ice.”
UConn researchers Penny Vlahos, Lauren Barrett, and Samantha Rush traveled to the Arctic in May of 2023 to gather samples from sea ice that is expected to be extinct by 2040 to catalog what the ice holds, but also to gather data to try to learn about the ice’s chemistry and clues about our future without it.
Arctic sea ice serves many purposes, such as storing carbon, reflecting sunlight, and serving as a habitat for arctic wildlife. Vlahos, a professor in the Department of Marine Sciences and head of the Environmental Chemistry and Geochemistry research group, explains there are two types of sea ice: the first is “annual ice,” which is about a meter thick and starts freezing in the winter, but completely thaws by the end of the summer. Then there’s the “multiyear ice,” which does not completely thaw by the end of the summer.
“The North Pole has a permanent ice cap that doesn’t completely thaw by the end of the summer, but that ice is going extinct and is expected to be gone by 2040,” says Vlahos. “We don’t understand how it’s going to affect climate, CO2 uptake, or how it will affect warming because right now, it is one of the largest sinks of CO2, but with a complete melt that’s anticipated in the summertime, it’s going to change the heat uptake and storage.”
The chemistry of the Arctic Ocean will change
Vlahos’s group was the first to study variations in salinity in seawater as it is influenced by the melting of sea ice in the Arctic by focusing on boron. They published a study in 2022, and this recent expedition builds on that previous research where they continued collecting field samples to measure the concentration of boron and its ratios to salinity.
The boron-to-salinity ratios are an important part of calculating the buffering capacity of the water, which is important because as the ocean absorbs more atmospheric carbon, it becomes more acidic, and as more fresh water from melting sea ice enters the equation, there is uncertainty about how it will impact the ocean’s carbon cycle. Vlahos’s group hopes to learn more about this dynamic chemistry to improve models that forecast what will happen as the ice is lost.
“We’re looking at two things, including how the chemistry changes in ice cores, because that freeze-thaw intensity that’s going to happen will change the chemistry of the Arctic Ocean because there’ll be so much more melting. Also, we want to capture the legacy of the multi-year ice to get the biogeochemistry of the cores of the ice that’s going extinct to see what we’re losing. This will show us the difference between freeze-thaw ice versus permanent ice, and then we can figure out how melt processes are going to change surface water chemistry in the future,” says Vlahos. “It’s a carbon sink as well, so the melting of the sea ice and more exposed ocean surface area could speed up the acidification of the world’s oceans.”
Rush, a second-year Ph.D. student, analyzed samples with Kitack Lee, a collaborator in South Korea who specializes in boron analysis, to see if boron and salinity conditions in the eastern Arctic are different than the parameters typically used in carbon calculations.
“We collected samples for boron to salinity analysis to see what those characteristics look like in sea ice versus the open water. We are looking to see if boron is behaving conservatively, meaning is it following the parameterizations that are set in the carbonate system, or if it is different, and how different it is,” says Rush. “We found that multiyear ice looks a lot different than annual ice. There is more conservative behavior of the boron in multiyear ice compared to annual ice, even though it still does differ from the accepted, open ocean ratio.”
Multiyear ice is potentially a good indicator of the boron-to-salinity ratio before climate change, and these measurements will help researchers get a grasp on exactly what parameters are shifting as more ice melts.
“It’s one thing to say the planet is getting warmer, and that tends to be one of the big focuses of climate change but we’re trying to understand, what that means for the carbon system and what does that do to other parts of the environment?” says Rush.
These findings are expected be published in 2024.
‘There’s so much we don’t know’
Vlahos says they secured funding from the U.S. National Science Foundation to join the Art of Melt (Atmospheric Rivers and the Onset of Sea Ice Melt) expedition, run by the Swedish Polar Research Secretariat. While onboard the Icebreaker Oden, the chief scientists worked on studying atmospheric rivers to learn more about how the climate will influence these intense precipitation events.
“Atmospheric rivers are just like streams of moisture that carry a lot of latent heat in them. The aim is to understand what their frequency will be in the future climate scenarios and also what role they have in ice melting,” says Vlahos.
While the expedition’s chief science group focused on the sky, Vlahos’s group focused on the ice. The icebreaker steamed to about 80 degrees north latitude, where the team spent their days coring and vacuum sealing ice, then they carefully thawed the samples to analyze the composition of the gas released as the ice melted.
“There’s so much we don’t know. For instance, we don’t know if there will be feedback that will encourage acidification or increased weathering, or if it will weaken the Arctic carbon sink because of the acidification. Those situations are what models need to predict in the future. Hopefully, this data can be used for building those models,” says Vlahos.
This was the second Arctic expedition for Barrett, a fifth-year Ph.D. student, who says it’s impossible to understand the otherworldliness of the frozen desert-like landscape without witnessing it firsthand.
“Seeing polar bears and seals, and all these different critters, and being part of that atmosphere and environment is not a replaceable experience. We have such respect and awe for that environment and that also drives our motivation.”
As for the gravity of their work studying ice that will soon be extinct in an environment most of the global population does not encounter or even think about every day, it’s quite abstract. For others on the expedition who have studied the Arctic for decades, Barrett says listening to their experiences about the changing environment is profound:
“Hearing their perspectives on seeing these changes with their own eyes over time makes it feel especially sobering. They can see and intuitively feel what is coming and what has been changing.”
“There’s a dramatic change that we’ve put into motion and when you see something happening so fast, and know that we caused, it’s a rude awakening,” says Vlahos.
This work will not only help understand the changes underway, but it can help shape policy. Barrett is embarking on a one-year fellowship with NOAA’s Knauss Policy Fellowship this spring to work with a member of Congress.
“We’re kind of powerless at this point to stop the decline in sea ice because the emissions are there, they are warming the atmosphere, and we don’t have the technology to take them back. That feels like a helpless situation, but I don’t see it that way. I see the power in working to understand what’s changing and to then promote policy, not to solve the fact that it’s happening, but rather how we solve the consequences of that specific change and the implications to the global carbon cycle. We need to think and readjust our global carbon models for that, and it requires all these nitty gritty details that individually aren’t as exciting but come together as something important.”
Vlahos adds another exciting element of the expedition – that this team is all women. Women are leading this research, producing the data, and helping to inform policy for the future of the climate and how we can prepare for it.
“As a Gen X kid, when I was in college studying engineering in the 80s, this would have been unheard of. I love that we’re doing this.”