Oregon State University is bringing together experts from across the United States to search for the oldest ice in Antarctica. The air bubbles trapped in ice from millions of years ago could tell us a lot about the earth’s last period of global warming. Ed Brook is a paleoclimatologist at OSU and the director of COLDEX, the Center for Oldest Ice Exploration.


This transcript was created by a computer and edited by a volunteer.

Dave Miller: From the Gert Boyle Studio at OPB. This is Think Out Loud. I’m Dave Miller. Oregon State University is bringing together experts from all around the US in a new research program to search for the oldest ice in Antarctica. The air bubbles that were trapped in that ice millions of years ago could tell us a lot about the earth’s last period of global warming. Ed Brook is a paleoclimatologist at OSU and he is the director of this new effort. It’s called COLDEX, The Center for Oldest Ice Exploration. Ed Brook, welcome to Think Out Loud.

Ed Brook: Good afternoon, Dave. Thanks for having me on.

Miller: Thanks for joining us. What’s your big idea behind this work?

Brook: Well, the big idea is to make a fundamental sort of transformation of our understanding of Earth’s climate history. I and others, as you mentioned, study ice and we use the air bubbles in the ice to understand the history of atmospheric greenhouse gases and climate and that’s only pushed us back about a million years into earth’s history so far. And we would like to push that back several million more years to get back to times when the climate was much warmer than it is today.

Miller: How much warmer?

Brook: If we can go back to about three million years ago, we think based on studies of ocean sediments and other things like that, that the average temperatures were 2-3° warmer and sea levels were tens of meters higher than they are now.

Miller: In other words, a climate that we may be heading towards by the end of the century, but we don’t have right now.

Brook: Yes, certainly. That’s part of our motivation is to try to get a better handle on how, when we add greenhouse gases to the atmosphere, the earth system responds. We know it’s going to get warmer. The question is, how much warmer, are there surprises in store? They’re also fundamental scientific questions we’re after.

Miller: As you mentioned right now, and for a lot of your career, you’ve been sampling and studying ice samples that are 800,000 or a million or so years old. What are the kinds of things you’ve already learned from those samples?

Brook: The biggest message from the ice so far has to do with how it compares to what we have done to the atmosphere since about 1750 or the start of the industrial revolution. Carbon dioxide, methane, nitrous oxide, the three most important greenhouse gases in the atmosphere are much much higher now because of human activities than they’ve ever been over that long 800,000 year time period. It’s crystal clear that human activities have caused those increases. So that’s the biggest message and then the second biggest message is that when we look at natural climate variations and compare them to natural variations in greenhouse gases, the two things are very, very highly correlated: warm climates correspond with higher levels of greenhouse gases, cold climates, lower levels of greenhouse gases.

Miller: How old is the oldest ice in the world or the oldest ice on Antarctica?

Brook: I’ll give you two answers because there’s sort of a distinct difference here. The oldest continuous ice core record, that is no breaks from top to bottom in the time history, is 800,000 years. That comes from a place in Central East Antarctica. The oldest ice with interpretable greenhouse gases, and it is actually about two million years, and that comes from a place in Antarctica where there’s old ice trapped in the mountains. Ice has flown into these regions and stagnated.

Miller: Ice has, it’s flown there?

Brook: It flows.

Miller: Sorry. Gosh, I’m learning a lot about ice today! I mean that’s true, but it still doesn’t fly, sorry, it flowed there.

Brook: The ice flowed there. Ice flows naturally, so the Antarctic ice sheet has actually been in existence for over 30 million years, but it’s been flowing from the summit down into the glacier systems for that whole time period. So most of the ice sheet is younger than a million, but there are places we know of and other places we think, there should be older ice that we can drill into.


Miller: So that’s why it seems like one of the, I suppose for you and your team, exciting challenges here is actually finding and then getting to that ice. What are those two aspects of this research going to entail, first identifying where this super old ice is, and then once you’ve done that, getting it?

Brook: On the first one, you’re absolutely right. It’s a major challenge. The ice sheet is several miles thick. We don’t have very many samples at the bottom. So the way we’re figuring out where to look is by a combination of understanding the flow and history of the ice with computer modeling to try to predict where old ice might be preserved and then imaging the interior of the ice with radar. It turns out that you can see some of the layering in the ice by flying radar over the surface from aircraft and also towing radar with snowmobiles. By doing this, we can build up educated guesses about where the old ice would be. The drilling part, when we want to collect a core, so drill from top to bottom, is very logistically intensive. It takes many years and lots of resources. So we want to be a little bit more sure about our science. And so we’re actually building a tool that will melt its way through the ice sheet over several weeks and measure things that can give us even more clues about what the age at the bottom is. And only then would we go to the drilling, which we know how to do. We don’t need to go deeper, probably than we’ve ever gone before. It’s cold, it’s hard to get there, and logistically intensive and kind of a long term effort.

Miller: Why is it going to take weeks to drill down originally to find the places to sample?

Brook: The probe that we are building with collaborators at the University of Washington is sort of a narrow cylinder that is heated by conducting electricity down a narrow wire. We want to go a kilometer and a half through the ice sheet and that just takes a long time to melt down through. Ice coring, when we want to collect a sample, that will actually take several years to do. And the reason is it, it just takes a long time to pristinely collect this piece of ice and not destroy it as you’re going down.

Miller: I want to talk about that as we go. I’m still curious. If somebody handed you a cooler that had some ice core rings in it or samples in it, how would you go about knowing how old that is?

Brook: This is a fundamental question. There are several techniques. One way is by measuring properties of the ice to tell us what things like the surface temperature of Antarctica, and we can compare those two records from the ocean, which have been dated over many, many years to kind of fit them into our longer term earth history.

Miller: In other words, there’s something in the structure, or the ice itself that can tell you how cold it was when that ice formed?

Brook: Yeah, that’s right. So it’s actually the water molecule itself, the H20 has different forms of hydrogen and oxygen in it. The ratios of what we call isotopes, or different forms of hydrogen and oxygen pretty directly reflect the surface temperature in Antarctica. It’s a very important piece of the climate history that we get from ice cores. To answer your question, though, there are some other techniques that we can use to measure the age of the ice. There’s a radioactive isotope of krypton that we can use as a dating tool. And there’s also an isotope of argon that has been gradually accumulating in the atmosphere. Argon is a noble gas, it doesn’t react with anything. And we know it’s time history as well. So we actually have multiple techniques for getting the ages.

Miller: If you’re just tuning in. I’m talking right now with Ed Brook, he is a paleoclimatologist at Oregon State University and he is the director of the new federally funded research group known as COLDEX. This is an OSU led effort to find and to study some of the coldest ice on Earth. Let’s move to the next part of this process. You go through this laborious process of finding and obtaining these pieces of ice, then what? I mean, one question I have is if one of things you really wanted to focus on is the air bubbles, the ancient air trapped in this? How do you get that out of a piece of ice without contaminating it with our air?

Brook: That’s a good question. And that’s what we do in my laboratory here at OSU, and in my collaborators’ laboratories around the country every day, actually. So we’ve built up some pretty good techniques for that. But basically we put the ice inside of chambers we can seal off from the laboratory air. We use vacuum pumps to remove the laboratory air and all the while we have to keep it cold. We’ve developed techniques for doing that and then sometimes we simply melt the ice to release the air and in other cases specifically for measuring carbon dioxide, which we care a lot about, we have a mechanical way of crushing the samples to release the air bubbles. So we spent a lot of time building devices to do this because it’s not something you can buy commercially and my students and postdocs spent a lot of time in the lab doing exactly this stuff.

Miller: Are you gonna get to go down to Antarctica again as a part of this new effort?

Brook: I certainly hope so. We had in fact had some plans to go a few years ago and a related project and Covid has gotten in the way of a lot of that. But yes, I definitely hope that I’ll be down on one of the teams and we’ll be sending a lot of other folks as well.

Miller: We’ve been focusing so far on the basic science, the research behind this effort, but that’s really just one, hugely important, but one component of the grant and what you’re going to be doing. Another really big one is translating this research, these findings into different venues, into the community at large, into classrooms. Can you give us a sense for that aspect of the effort?

Brook: Certainly, maybe I should say as some background context, this is something called the National Science Foundation Science and Technology Center Award. STCs exist across all fields of science funded by NSF. We definitely have a mission to not just do the research but also to bring that, as you said, into other venues. So with collaborators at the American Meteorological Society and at Dartmouth College, we’re building professional development opportunities for K-12 teachers associated with ice core science and for instructors at community colleges and minority serving institutions, also sort of focused on ice core sciences. These are week-long workshops in the summer where they will come here and learn about our work and get to do some of it. That’s a big part of the center as well.

Miller: Is it fair to say that this is a part of a real change in the way science works? Over the course of your career, more of an emphasis and effort put into building in accessibility and popular translation from early on as opposed to waiting, maybe a number of years, for basic research to filter into textbooks or to filter into classrooms or popular conversations?

Brook: I think that’s a fair statement, I believe. I started doing science as an academic researcher in the early 90s and we were talking about these things then and people were doing it. But as you said, having that be infused into all aspects of science is a newer thing and I think it’s good. It makes us think a little harder about the importance of what we’re doing.

Miller: I want to go back to what you were talking about at the beginning, that this is going to give us a deeper understanding of climate history and in a way that relates to our climate future. I’m wondering what that means in practice because obviously we’ve all gotten the message, not all of us have internalized it and some of us have chosen, with blinders on, to ignore it. But if the blinders are off, we understand that humans are causing global warming, causing climate change by putting greenhouse gases in the air and we know that the more greenhouse gases there are, the hotter the earth gets, what more can we learn that would actually have an effect on policies going forward?

Brook: I think that the broadest scale answer- and this is not just an answer for ice core research, but it’s really an answer for studying past climate in general, is that yes, it is going to get warmer if we keep adding greenhouse gases to the atmosphere. There is the question though, about how much warmer, technically we call this the climate sensitivity, how much temperature change you get for a given amount of greenhouse gases and that’s a somewhat uncertain number, and I think it does have a bearing on how we decide about how risky future climate is. And so the more we can nail down how sensitive the system is, the more confidence we should be able to have in our predictions and that should help us make better decisions. But at the base level we know a lot about future climate and our current trajectory is kind of worrying. So that message is loud and clear already.

Miller: Ed Brook, thanks very much for your time today. I appreciate it. Congratulations.

Brook: Thank you for having me.

Miller: Ed Brook is a paleoclimatologist at Oregon State University and the director of this new National Science Foundation funded effort, COLDEX.

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