Stephen Ackley

Your research focuses on the growth, structure, and properties of Antarctic sea ice. Can you explain how you became interested in this field?

I was drafted into the Army during the Vietnam War and assigned to the US Army Cold Regions Research and Engineering Lab in the early 1970s. After my service, I was hired as a Research Geophysicist. The lab had several pioneers in Arctic sea ice research, such as Willy Weeks, and I was fortunate to make trips to the Arctic to work with Willy and others at that time. My focus then shifted to the Antarctic where little work had been done previously. I was drawn to sea ice research because it’s so interdisciplinary. Sea ice affects and is affected by the atmospheric and physical oceanographic conditions and is also important to the region’s ecology. Early in my career, we really didn’t know a lot about particularly Antarctic sea ice, so we were able to conduct simple measurements of ice thickness and properties that were foundational research in the modern era on Antarctic sea ice.

Speaking of foundational research, you have been a leader in the field of modern Antarctic sea ice research since the 1970s. How has the field changed over the last 50 years? What new research questions are you most eager to investigate?

Our methods have changed a lot over the course of my career. When I first started, we went out on the ice with measuring sticks and ice thickness drills and corers. Now we have much more advanced technology, like satellites, remote data buoys, and UAVs (underwater autonomous vehicles). With UAVs, we can see what’s going on underneath the sea ice and at the ice bottom in a more comprehensive way than by core or thickness sampling from the surface. GPS technology and satellite data from remote regions have also allowed long-term tracking and time series data collection from data buoys that was not available until much later than when I first started in the field.

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It sounds like there have been amazing advances in methodology. With all these new technologies, what new research questions are you eager to investigate?

Another interdisciplinary question is how sea ice affects climate and ecology.

We know that sea ice formation and brine rejection play an important role in bottom water formation, but questions remain about relationships between sea ice and bottom water. Another interdisciplinary question is how sea ice affects climate and ecology. These require process studies involving atmosphere, ocean, and biological measurements at short intervals temporally and spatially, and yet extending over an entire annual cycle and over very large spatial scales. These can only be done by combining the high-resolution field measurements with satellite imagery and extensive use of autonomous data buoys over longer periods.

Lots of exciting work on the horizon. Looking back at your eleven field seasons in the Antarctic and four in the Arctic, how do the two polar regions compare? Do you have favorite memories from your field work?

In terms of their oceanography, the Arctic Ocean is isolated somewhat from the world ocean as it is mostly surrounded by continents at higher latitudes. In contrast, the Southern Ocean is open and circumpolar to the world oceans, extending into lower latitudes and hence is more dynamic and interactive with the ocean circulation. For example, waves generated by storms far away from the sea ice edge impact both the sea ice development and retreat in the Antarctic, unlike in the Arctic where waves and swell are blocked by the continents. Logistically, the Arctic is also much easier to get to. My first trip to the Arctic was by taking a plane based from a commercial airport in Alaska for a few hours-long flight to a drifting ice station. Trips to the Antarctic sea ice were by icebreaking ships and took a week or more to get to the ice. In a remote environment like the Antarctic, there are lots of logistical challenges to getting into ice ice-covered regions and conducting research.

One exception to going to the Antarctic by vessel provided one of my favorite memories. I made a trip by air to McMurdo Station in order to fly from McMurdo to drop some drifting buoys by parachute on the Weddell Sea pack ice, which is on the other side of Antarctica from McMurdo. These drops were done by the NSF C-130 aircraft but the distance to the drop area and back to McMurdo is too long for the C-130 to make without refueling. So, on the way back from the successful drops of the buoys, we landed at South Pole Station to refuel, which was done while the engines were running. So, my first and only trip ever to South Pole lasted about a half an hour, just enough time to run over to the “barber pole” site and take a couple of pictures and get back to the plane before it took off again for the return to McMurdo after refueling. By the way, the buoys gave us data on the atmospheric temperature and pressure and drift of the sea ice in a region never measured before for up to a year, so it was a very successful experiment as well.

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What a great story! Now thinking about your work beyond fieldwork, you were the founding chair of the SCAR Expert Group on Antarctic Sea Ice Processes and Climate (ASPeCt). Can you explain your role as chair and co-chair? Are you particularly proud of any outcomes from your work with ASPeCt?

Neither myself nor the field of research would be where we are today without this international coordination and cooperation that ASPeCt – with SCAR support – from the outset has provided.

The main goal of ASPeCt when it was first founded was to standardize a set of protocols to provide circumpolar sea ice thickness around Antarctica based on the hourly ice observations taken during ship traverses through the ice by vessels from the US, Australia, Russia, Germany and others. The data from many individual cruises were then archived in data centers and resulted in the first circumpolar sea ice thickness distribution study, subsequently used in validating models and satellite remote sensing in many studies. Other data archives were also established for ice thickness data obtained from drilling lines and ice core data on ice physical and biological properties. ASPeCt now works on sharing sea ice data with the Southern Ocean Observing System (SOOS).

ASPeCt has helped particularly by establishing Antarctic sea ice as one of the main topical areas for SCAR. It has helped scientists coordinate their research across national programs and maximize the limited national icebreaking vessel capabilities through international participants. My own experience has been on or with vessels from Russia, UK, Germany, and Sweden as well as the US Coast Guard and the NSF vessels. Neither myself nor the field of research would be where we are today without this international coordination and cooperation that ASPeCt – with SCAR support – from the outset has provided.

Your fruitful work with ASPeCt and collaboration with a diverse group of scientists was highlighted in the announcement for your receipt of the 2022 SCAR Medal for International Scientific Coordination. Can you speak about your experience working with international teams and about the value of diversity?

International collaborations are especially important in polar research since we have limited funding and logistical resources.

Yes, I think diversity and getting more types of people involved in science is important. I’ve worked with many great women scientists and am proud to have invited several of them for their first Antarctic participation on the projects I’ve headed. I’m currently at the University of Texas at San Antonio (UTSA), which is a minority-serving institution with over 50% student enrollment from underrepresented minorities. I have had both undergraduate and graduate participants involved with my sea ice research both in the field and in the lab. In terms of international collaborations, a career highlight for me is the US-USSR Ice Station Weddell in 1992, the first Antarctic sea ice drifting station. Other collaborations with both researchers and on vessels have been with Belgium, Germany, UK, and Australia. A recent example of collaborative fieldwork in the Arctic is the MOSAiC expedition (Multidisciplinary drifting Observatory for the Study of Arctic Climate), which had hundreds of participants from many countries. International collaborations are especially important in polar research since we have limited funding and logistical resources.

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Continuing with the idea of getting more people involved, what advice would you give to early career scientists wanting to get involved in Antarctic research?

I’d recommend pursuing an undergraduate degree in any science field that interests you. Antarctic research is so interdisciplinary, so any field of science you may want to study is relevant. If you’re interested in Antarctic research but not necessarily doing science, also consider working on the logistics side. If there are faculty at your university that are involved in polar research, try to ask them about their research, and see if they will suggest even a course project that will help you gain entry into their own or other polar research. Finally, if you’re looking for an opportunity to conduct field work, I suggest applying for field school courses. There are several of these for sea ice and glaciology. This experience will help get you out in the field and you’ll develop skills that will be useful for future fieldwork opportunities as well as network with students and researchers at other institutions with polar interests. These courses have been especially useful to early career scientists just starting in polar research, even if their interests are in subject areas not in field work itself, but in theory, modeling, or remote sensing, for example.

Thank you, Steve, for that advice and for speaking with me about your research.