.jpg)
In recent years, the extent of Antarctic sea ice has declined rapidly, with changes observed on a scale unprecedented in recorded history. These changes may affect the global environment and our daily lives through their influence on ocean circulation and the climate system. The changes occurring in the Antarctic and Southern Ocean regions are no longer merely distant polar events. We spoke with Dr Alex Fraser of the University of Tasmania and Dr Kazuya Kusahara of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), both leading researchers in this field, about the importance of Antarctic and Southern Ocean research in the age of climate change and the significance of research collaborations between Australia and Japan.
Changes in the Antarctic and Southern Ocean Regions Affect the Entire World
— Climate change has now become a major global challenge. How do you view the current global environment? Please share your thoughts from the perspective of your research expertise in the Antarctic region.
Dr Kazuya Kusahara (hereafter “Kusahara”):
Although Antarctica and the Southern Ocean are far removed from Japan, significant changes have begun to emerge in the region’s oceans and cryosphere in recent years. Moreover, this is not simply an issue confined to Antarctica. The Southern Ocean absorbs heat and carbon dioxide from across the planet and plays a vital role in sustaining global ocean circulation and the climate system; consequently, changes in this region can affect the entire world.
.jpg)
From the perspective of my field of expertise in ocean and sea-ice research, an important point is that changes in the Antarctic region are occurring through the complex interconnection of climate, the ocean, sea ice, ice sheets, and ecosystems. For example, ocean warming, the melting and structural changes of ice sheets and ice shelves, and fluctuations in sea-ice distribution are not independent phenomena; they influence one another. Furthermore, these changes are also believed to be linked to the weakening of deep ocean circulation, often referred to as the planet’s conveyor belt. The loss of ice sheet mass caused by global warming leads to rising sea levels, which have a significant impact on people living in coastal regions. In addition, changes in the Southern Ocean caused by freshwater inflows associated with changes in the cryosphere may also affect the global climate and ecosystems.
These changes are also serious from the perspective of Antarctic biodiversity. Major changes in sea ice and the marine environment may affect the ecosystems of the Antarctic Ocean and the organisms that inhabit it. Research reports in this field also emphasise that changes in the Antarctic and Southern Ocean regions are issues that extend beyond the natural environment to human society and coastal regions and that urgent research and international action are required. For this reason, I view Antarctica and the Southern Ocean not as special problems in distant places but as regions of critical importance when considering the future of the planet as a whole. I believe that correctly understanding the changes now taking place and clarifying the mechanisms behind them are essential for considering the future of the climate and the marine environment.
Dr Alex Fraser (hereafter “Fraser”):
I also recognise climate change as an extremely serious global issue. Its effects are already becoming a reality, and the pace of change is accelerating. My area of expertise is the study of the Antarctic sea-ice system. From that perspective, let me explain what kinds of changes are occurring in the sea ice surrounding Antarctica.
.jpg)
Until around 2015, Antarctic sea ice had been increasing. However, between 2016 and 2023, that trend declined sharply. In other words, in less than a decade, the sea ice surrounding Antarctica changed dramatically from a state of greater than ever before to one of lower than ever before. This can be described as an extremely large negative anomaly.
In 2023, there was a deficit of approximately two million square kilometres of sea ice that would normally have formed. This is unprecedented within satellite observation records dating back to 1978. This phenomenon was a major shock to the research community, and we have been working intensively to determine its causes. Dr Kusahara is a world-leading researcher in the field of sea ice–ocean interactions, and he plays a central role in clarifying the mechanisms behind phenomena such as this.
In addition to the overall decline in sea ice, “landfast sea ice”, which is ice that is attached to the coastline, has also decreased significantly. As Dr Kusahara explained, the extent of landfast ice in summer has now fallen to around half of its former level. In recent years, technologies for measuring the thickness of sea ice have also advanced. Satellites equipped with altimeters can now measure the height of sea ice and estimate its thickness from those measurements, which was impossible twenty years ago. As a result, there are concerning trends regarding not only the extent of sea ice but also its thickness.
We believe that these changes are not temporary and are becoming the “new normal”. The oceans surrounding Antarctica are warming overall, and water temperatures are rising even beneath the ice. The atmosphere is also warming. Taken together, these factors suggest that the continued decline of Antarctic sea ice throughout this century is unavoidable.
Kusahara:
In this sense, the Southern Ocean surrounding Antarctica plays a central role within the global ocean system. What is particularly interesting is that the Antarctic coastal region serves as an important link between processes occurring near the ocean surface (surface waters) and deep waters. In other words, understanding the processes of the Southern Ocean is critically important for understanding the structure of the ocean horizontally and vertically.
Global warming is altering the state of sea ice, the oceans, and the atmosphere. These signals of change are not confined to the Southern Ocean, and they will eventually propagate throughout the world’s oceans. Antarctica is geographically close to Australia but far from Japan. However, for those of us living in Japan, the changes taking place in the Southern Ocean and Antarctica are by no means irrelevant, and they carry significant implications for our lives.
Fraser:
What happens in Antarctica certainly does not remain confined to Antarctica. For example, thermohaline circulation, which regulates global ocean currents, is largely controlled by sea-ice formation around Antarctica. Dr Kusahara’s research has successfully modelled this important climate process numerically using computer simulations that clearly demonstrate how Antarctica is connected to the wider world.
I regard sea ice as an extremely important indicator. This is because sea ice can be observed and measured using satellites. In other words, monitoring changes in sea ice can serve as an early warning indicator for detecting changes that may affect our lives in the future.
Participating in Joint Antarctic and Southern Ocean Research at Australian and Japanese Research Institutions
— Could you both tell us again about your research on sea ice and the oceans, as well as your careers to date? First, Dr Kusahara, if you would.
Kusahara:
After obtaining my degree from Hokkaido University, I engaged in research on the cryosphere and sea ice at the Atmosphere and Ocean Research Institute of the University of Tokyo and the Institute of Low Temperature Science at Hokkaido University. Currently, I am a member of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). My research focuses mainly on the Antarctic and Southern Ocean region.
.jpg)
Dr. Fraser and I have known each other since my time at the Institute of Low Temperature Science, Hokkaido University. We later became colleagues again at the Antarctic Climate & Ecosystems Cooperative Research Centre (ACE CRC) in Hobart, Tasmania, Australia. ACE CRC was an international research organisation that studied the role of the Antarctic region in the global climate system and its impact on marine ecosystems. It completed its mission in 2019. At ACE CRC, Dr. Fraser and I happened to sit next to each other, which allowed us to exchange ideas on a daily basis while conducting our research. I feel that this connection later led to collaborative research between Australia and Japan.
At the Institute of Low Temperature Science, Hokkaido University, our research mainly focused on polar region observations. I specialised in simulation research aimed at reproducing the movements of the ocean and sea ice using computer models. Although observations are essential for understanding what is happening in the field, the amount of information that can be obtained is limited. In vast and difficult-to-observe regions such as Antarctica, it is not easy to understand the overall picture through observations alone. Therefore, by developing simulation models that can successfully reproduce observational results and by examining those results in detail, we have continued our research to clarify how the ocean and sea ice move and why such changes occur.
——Dr. Kusahara, what kind of research were you engaged in at ACE CRC?
As a member of the Sea Ice Group, I worked on clarifying the causes of recent sea ice changes in the Southern Ocean by comparing and validating satellite and observational data against numerical model results. In addition, we investigated the impacts on sea ice, ocean circulation, and ice sheet melting of the large-scale calving of the Mertz Glacier (approximately 70 km long and 30 km wide), which occurred off the coast of Adélie Land, Antarctica, in 2010.
In our numerical model, we conducted an analysis akin to a so-called "dye-tracer experiment", tracking the high-salinity brine released during sea-ice formation. We also investigated the spread of high-density shelf water originating along the Antarctic coast, which serves as a driving force for deep-ocean circulation. I believe that this kind of research is unique to numerical modelling, and it allows us to visualise processes and investigate the underlying mechanisms that are difficult to capture through observations alone.
——Now, Dr. Fraser, can you tell us about your specialty?
Fraser:
I first studied Physics and Computing at the University of Tasmania, where I obtained my bachelor’s degree. I then conducted honours research on atmospheric remote sensing using artificial satellites and cloud observations in Antarctica. I subsequently entered the doctoral program at the same university, where I researched remote sensing of sea ice in Antarctica, particularly landfast ice fixed to the coastline.
.jpg)
After completing my PhD, I spent three years as a postdoctoral fellow at the University of Tasmania. In addition, from 2013 to 2015, I received a fellowship from the Japan Society for the Promotion of Science (JSPS) and spent two years conducting research at Hokkaido University. During this period, I met Dr. Kusahara, and we became very close friends. I remember that we had lunch together almost every day. I then returned to the University of Tasmania, where I conduct research in the Australian Antarctic Program Partnership. After I returned to Australia, Dr Kusahara came to Tasmania, and we once again carried out research together at ACE CRC.
Let me say a little bit about my current research as well. I am currently affiliated with the University of Tasmania and am undertaking a four-year research project with support from the Australian government’s Australian Research Council (ARC) Future Fellowship. My current research focus is landfast sea ice, which I mentioned earlier. As I mentioned earlier, the extent of summer fast ice has declined significantly in recent years. However, we still do not fully understand what kinds of changes are occurring during winter. This is because fast ice is extremely difficult to observe and map. As part of my current research, I am developing methods for accurately mapping fast ice, as well as investigating the reasons why it is decreasing during summer.
As part of this research, Dr Kusahara and I published the world’s first review paper on Antarctic fast ice in 2023. Twenty-three researchers from around the world contributed to the paper, and Dr Kusahara served as one of the section leaders. It was published in a highly influential academic journal, and since its publication in 2023, it has already been cited more than 100 times. This paper is probably the only review article that systematically summarises the importance of fast ice and explains why it is necessary to continue observing and understanding it. At present, much of my research is devoted to the observation, modelling, and understanding of fast ice.
— Do you have any memorable stories from the time you and Dr Kusahara worked together at ACE CRC in Tasmania?
Fraser:
One memorable incident was when, by chance, we were both asked to review the same paper at the same time. Do you remember that?
Kusahara:
Ah yes, I remember that (laughs). Although I cannot remember the details exactly…
Fraser:
As peer reviews have to be conducted anonymously, we could not discuss the contents directly, but somehow we realised that we were reviewing the same paper. At that moment, I realised just how concentrated Hobart was with experts in this field. I felt that Dr Kusahara’s arrival significantly raised the standard of research in this field, and I was very proud of that.
Another memorable aspect was the close relationship between our families. Dr Kusahara’s family and my family became very close, and we quickly felt at ease with one another. That is why I felt very sad when Dr Kusahara returned to Japan. Well, when you returned to Japan, you gave me a grilling plate for jingisukan, didn’t you? That was a wonderful cultural exchange. By the way, how did you manage to get hold of that plate in Hobart?
Kusahara:
I brought it with me from Hokkaido (laughs). I’m very pleased that you liked it.
— Dr Kusahara, have you continued your interactions with Australian researchers even after returning to Japan?
Kusahara:
After returning to Japan and moving to JAMSTEC, where I am currently based, I have continued collaborating with Australian researchers through sharing model data, joint analyses, and model comparisons. As he mentioned earlier, I also had the opportunity to work with Dr Fraser on a review paper concerning landfast sea ice. Because of the COVID-19 pandemic, I have not yet been able to return to Australia since moving back to Japan. However, the widespread use of online meetings has enabled us to continue writing papers and discussing research, which has been extremely valuable.
Since returning to Japan, I have been conducting high-resolution modelling in East Antarctica, including Lützow-Holm Bay, where Syowa Station is located, and the offshore region near Totten Glacier. In particular, I have used Dr Fraser’s landfast sea ice data for the configuration and validation of numerical models. Recently, collaborations between Australia and Japan in polar research have begun to regain momentum, and I have had opportunities to reconnect with former colleagues from the ACE CRC at workshops and similar events. Whenever I attend such events, I feel very pleased that our research connections continue today.
2017 - participating in a grant project supported by the Australia-Japan Foundation
— I understand that the two of you participated together in an Australia-Japan Foundation (AJF) grant project in 2017. What kind of research exchange did you undertake?
Kusahara:
As part of the 2017 AJF project, Dr Fraser and I led three PhD students from the University of Tasmania to participate in a sea ice field training programme conducted at Lake Saroma in Hokkaido. This training programme was organised mainly by the Institute of Low Temperature Science and the Faculty of Fisheries at Hokkaido University. Through conducting observations directly on the ice, we learned the fundamental methods and practical know-how of sea ice observation while also sharing those experiences with the students. In addition, instruments used for polar observations were tested at Lake Saroma, making it a valuable opportunity to deepen our understanding of polar research and gain practical knowledge through exchanges with researchers and engineers.
Lake Saroma is a semi-enclosed brackish lake that, although influenced by seawater, freezes over completely during winter. As a result, although the ice formed there has properties very similar to sea ice, it is much less affected by waves than the open ocean, which provides the major advantage of allowing relatively safe observations to be carried out on the ice. In addition, it is an extremely valuable site since researchers can access sea ice directly from land, which means it supports sea ice observations without the need for a ship. So it is an outstanding field site for both education and research on a global scale.
Fraser:
The three students from the University of Tasmania were researching sea ice, but they had few opportunities to visit Antarctica. This is because securing the logistics required for field research in Antarctica, such as transport and equipment, is extremely difficult. Therefore, the project at Lake Saroma provided a valuable opportunity for them to experience first-hand the very subjects they were studying in their doctoral research. Without having to travel to Antarctica, they were able to gain practical experience in sea ice observation and field surveys. We believe that an environment such as Lake Saroma is extremely effective in allowing more people to experience the realities of sea ice research, and it also has great significance from the perspectives of education and human resource development.
Kusahara:
This initiative was also featured in the local newspaper, which published an article about the Australian participants conducting sea ice observations at Lake Saroma. After the training programme, some of the participants joined us in giving presentations at high schools and colleges of technology, which also led to outreach activities aimed at communicating the importance of sea ice and polar research. I believe that one of the major achievements of this AJF project was its successful integration of research, education, international exchange, and community engagement.
— Do you feel that the AJF grant provided a meaningful experience for the students from the University of Tasmania?
Fraser:
Yes, it was undoubtedly a highly meaningful experience. Experiences like these in the field become unforgettable memories for life. It allows students to step outside the laboratory, where they spend every day in front of a computer, and learn in a natural environment. Experiences of this kind are truly valuable and difficult to obtain elsewhere.
They have certainly had a positive influence on the students’ subsequent career paths. In fact, one of the three participating students is now working for Australia’s Integrated Marine Observing System (IMOS). Another student now works as a graphic designer for scientific diagrams. And the third is employed by a software company in Tasmania that handles marine-related data, where she works to advance the field of visualising oceanographic data.
In 2025, the Australia-Japan Antarctic Science Workshop was held with support from a grant provided by the Australia-Japan Foundation.
— I understand that Dr Fraser also participated in the AJF grant project during 2024–2025. Compared with the first project, did you notice any changes in the collaborations in research between Australia and Japan?
The second project was very different in nature from the first project. The background to this was the joint statement issued by the leaders of Australia and Japan in 2008. The statement recognised that continued cooperation in scientific research in Antarctica would play an important role in understanding the global impacts of climate change, and it affirmed a commitment to further strengthening collaboration in this field. This became the starting point for joint efforts by Australia and Japan to better understand climate change in Antarctica and its impacts.
.jpg)
Credit: Mark Horstman
In response to this statement, the first Japan-Australia Antarctic Science Workshop was held in 2009. Since then, the workshop has been held every three years, alternating between Australia and Japan. It was held in Australia in 2012 and in Japan in 2015. In 2018, the workshop was again held in Japan, but after that, it became difficult to hold face-to-face meetings because of the COVID-19 pandemic. Following this trend, the fifth Australia-Japan Workshop on Antarctic Science was held at the National Institute of Polar Research in Tokyo in 2025. The 2024–2025 AJF grant project was intended to support this workshop.
Securing funding for this kind of international collaboration is not easy. That is why it is extremely important for researchers to be able to use frameworks, such as the Australia-Japan Foundation (AJF), to secure funding that supports ongoing collaborations.
It is important for Australia and Japan to continue sharing observational data and promoting exchanges of research personnel in the Antarctic and Southern Ocean region.
— What role do you think Australia and Japan should play together in addressing global challenges, such as the conservation of the Antarctic region and responses to climate change?
Fraser:
First, one thing Australia and Japan have in common is a high level of scientific credibility. In fact, between 2016 and 2024, both countries ranked among the world’s top ten in terms of the number of papers published on Antarctica and the Southern Ocean. This means that we are at the forefront of countries seeking to understand Antarctica and its role in the Earth’s system. In other words, we already possess substantial knowledge, and we have a responsibility to communicate that knowledge to policymakers and those involved in climate policy in our respective countries.
Australia, in particular, bears a significant responsibility. This is because around 42% of Antarctica is administered as the Australian Antarctic Territory, and Australia, therefore, plays an important role in its conservation and management. Japan, on the other hand, although geographically distant from Antarctica, possesses major strengths in industrial and scientific technology. In particular, the development of observational instruments is an important field in which a country like Japan is especially well placed to contribute.
For example, there is a long observational record of sea-ice extent that dates back to 1978, and the sensors used for these observations were developed in Japan. More specifically, these observations rely on a highly important satellite observation instrument known as “AMSR2”, which enables us to continuously record daily sea-ice extent. Furthermore, Japan also possesses major strengths in the field of supercomputing. For modelling researchers, such as Dr Kusahara, supercomputers are indispensable, and their importance has grown even further now that AI (machine learning) plays an increasingly significant role in research. Today, supercomputers have also become an essential tool for satellite observation researchers like myself.
By combining these strengths, cooperation between Australia and Japan can generate synergies rather than merely additive benefits. And I believe we have a responsibility to maximise the potential of this collaboration. The 2025 Australia-Japan Workshop on Antarctic Science was also an important opportunity that was made possible through the support of the Australia-Japan Foundation (AJF). In fact, over the past year, a white paper has been published, led by Japanese researchers working in Australia, on how oceanographic observations around Antarctica should be strengthened. This is one of the outcomes of the workshop, and it aims to strengthen the coordination of observational systems in East Antarctica and deepen our understanding of areas that remain poorly understood.
At present, there are still many areas of the Antarctic continental shelf where even the water depth is not accurately known. Because it is extremely difficult to send research vessels into these regions, even basic data are lacking. However, by combining the resources and expertise of both countries, we should be able to achieve a deeper understanding of these still-unexplored areas.
Kusahara:
The Antarctic and Southern Ocean regions are so vast that no single country can fully understand them or conduct continuous observations and predict their future on its own. Moreover, the Southern Ocean is not merely the ocean surrounding Antarctica; it connects the Atlantic, Indian, and Pacific Oceans while also linking the surface ocean with the deep ocean. It is therefore a vital component of the Earth’s climate system. It plays a major role in regulating the global climate by absorbing heat and carbon dioxide from across the planet, and changes in the Southern Ocean affect not only the Antarctic region but the world.
For that reason, I believe how to understand the Antarctic and Southern Ocean is directly linked to understanding the climate system. In particular, it is extremely important to clarify how ocean circulation, ice sheets, ice shelves, sea ice, and ecosystems will change with future global warming. Furthermore, I believe it is also an important challenge to understand why the properties and volume of Antarctic Bottom Water are changing and how these changes influence global ocean circulation and climate.
In this context, I believe Japan and Australia have a highly complementary relationship. Both countries maintain Antarctic stations in East Antarctica and conduct continuous observations and research in the surrounding region. By promoting the sharing of observational data, research collaborations, and personnel exchanges, we can achieve levels of understanding that neither country could attain independently. In particular, it is important to advance integrated research that combines observations and numerical modelling. I believe it is desirable to deepen cooperation by incorporating observational findings into models while also using those models to understand broad-scale and long-term changes that cannot easily be captured through observations alone.
I believe the role that Japan and Australia should play is to provide reliable knowledge to the international community by linking observations, modelling, and human resource development, particularly in the East Antarctic region. The conservation of the Antarctic region and responses to climate change cannot be achieved by any one country acting alone. For this reason, I believe there is great value in Australia and Japan, which are closely connected both geographically and scientifically, continuing to collaborate over the long term.
— Lastly, as a researcher, could you tell us about any themes or research goals that you would like Australia and Japan to work on together in the future?
Fraser:
This was, in fact, at the very heart of the discussions held at the workshop in Tokyo last year (2025). The workshop also identified specific projects to be pursued over the next three years. The starting point for our strong sense of awareness is the rapid decline in Antarctic sea-ice extent that has occurred over the past decade. To understand the causes and consequences of this change, we are now pursuing research efforts with a very high degree of urgency.
One particularly important theme is the use of satellite observations. We held extensive discussions on how newly operational satellite data can be utilised to better understand the physical characteristics of Antarctic sea ice. Furthermore, the use of AI has become a major focus in current research. AI will become increasingly important in helping us extract greater value from the enormous volume of observational data.
In 2028, an Australian-led Antarctic research voyage is planned with the aim of deepening our understanding of the marginal ice zone. This is the outer edge of the sea ice, where it directly interacts with waves in the Southern Ocean. It is currently thought that changes in this marginal ice zone may be contributing to the decline in Antarctic sea ice. As with previous expeditions, we plan to invite Japanese researchers to participate in this research voyage. In fact, since 2003, Japanese researchers have consistently taken part in Australian sea-ice observation voyages, and this cooperative relationship will continue into the future.
Furthermore, both countries share common research facilities, called wave ice tanks. These are experimental facilities in which sea ice is recreated in a low-temperature tank environment, allowing researchers to study how the ice responds when waves are introduced. This is an important method for understanding the physical properties of ice and how it is broken up by waves, and I believe this will become a key area for future Australia-Japan collaborations.
.JPG)
An Australian student studying plankton at Lake Saroma
Another extremely important area is the exchange of early-career researchers. I myself spent two years in Sapporo from 2013 under a JSPS fellowship. Many researchers in our group have benefited from this programme. Over the years, researchers from Japan have come to Australia, and many sea-ice researchers from Australia have also gone to Japan. These exchanges are supported by the Japanese government, and they play a critically important role in Australia-Japan research collaborations. In fact, it would be fair to describe this programme as the very foundation of our cooperative relationship. Without this, I do not think we would have reached our current understanding of the sea-ice system.
Each of these efforts may be a small step, but by building upon and integrating them, we believe it will become possible to make more reliable predictions about future changes in Antarctica and their impacts on the global ocean and climate.
Kusahara:
One of the themes I would like to focus on in the future is achieving an integrated understanding of how the ocean, sea ice, ice sheets, and ice shelves in the Antarctic and Southern Ocean regions interact. In particular, I would like to clarify how changes in sea ice variability, ice sheet melting, and freshwater inflows under global warming will affect future circulation of the ocean and the climate. As my speciality is numerical modelling, I would like to continue advancing high-resolution modelling that combines observational data with model simulations. In particular, with a focus on the Antarctic coastal region, I would like to investigate in greater detail landfast sea ice, coastal ocean circulation, basal melting beneath ice shelves, and the formation of dense water.
In addition, through collaborations with universities and research institutions in Australia and Japan, I hope to advance integrated research on East Antarctica through sharing observational data, model intercomparisons, joint analyses, and researcher exchange programmes. As Dr Fraser also mentioned, Australian research teams have particular strengths in satellite-based observation and data acquisition. In contrast, Japanese research teams can contribute through numerical modelling research using AI and supercomputers. In other words, by integrating modelling research and observational data from both countries, we can aim for a more accurate understanding. I believe it will become increasingly important to continue collaborations that link observations and modelling while making the most of the respective strengths of Australia and Japan.
(Profile)
Dr Alex Fraser
Marine and sea-ice researcher at the University of Tasmania, Australia. He specialises in satellite remote-sensing research on Antarctic sea ice, with a particular focus on the observation and analysis of landfast sea ice that is fixed along the Antarctic coast. After obtaining a degree in Physics and Computing from the University of Tasmania, he worked on satellite remote-sensing research on Antarctic clouds. During his doctoral studies, he researched the distribution and variability of landfast ice in East Antarctica. From 2013 to 2015, he was based at the Institute of Low Temperature Science, Hokkaido University, as a fellow of the Japan Society for the Promotion of Science (JSPS), where he promoted collaborative research with Japanese researchers. Since then, he has continued to promote Australia-Japan research exchanges in the Antarctic and Southern Ocean regions.
Dr Kazuya Kusahara
Marine and sea-ice researcher at the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). He specialises in numerical modelling research on ocean circulation and sea-ice variability in the Antarctic and Southern Ocean regions. After obtaining his degree from Hokkaido University, he continued his research on the ocean and sea ice at the Atmosphere and Ocean Research Institute of the University of Tokyo and the Institute of Low Temperature Science at Hokkaido University. From 2015 to 2019, he participated in international collaborative research on Antarctic sea-ice variability and ocean circulation at the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) in Hobart, Tasmania, Australia.