Climate & Environment



Glaciological Balance of the Glacial Arctic Ocean in the context of the International Polar year

You are certainly aware that polar bears are threatened by the Arctic sea-ice loss caused by global warming. This debated topic is being investigated by Pascaline Bourgain, who is studying the effects of warm water entering the Arctic Ocean. One of the strengths of her study is that she analyzed huge amounts of data as well as obtained new measurements during an unforgettable three-month icebreaking expedition in the Arctic. At a global scale, sea-ice loss is a serious threat to ecosystems (disturbance of fauna and flora) and physical systems (e.g. ocean circulation). It affects the entire human population, particularly the Inuits, who are forced to adapt their way of life to changing sea-ice conditions.
My research focuses on the Arctic Ocean and its interaction with sea ice that has strongly retreated, showing evidence for current global warming intensification in the Arctic. I am particularly interested in the halocline layer, located between 50 m depth and 200 m depth, and its spatio temporal variability. This layer is of first importance as it separates the surface from the main Arctic ocean heat reservoir located around 300 m depth.


After earning my French Baccalaureate (science section), I enrolled in a two-year college preparatory course in mathematics and physical sciences at Lycée Faidherbe in Lille, France. I was then admitted to the École normale supérieure of Paris, in the Earth Atmosphere Ocean department. During my three years of studies, I had the opportunity to participate in several internships, including one abroad, in a variety of fields ranging from geology to climatology. In my final year, I completed a Master's degree at the Sorbonne Université in physical oceanography. During my final internship, I discovered that I had a true passion for the Arctic Ocean, which I have been fortunate to be able to study for three additional years while completing my PhD.


Global warming seems to be accelerated in the Arctic. In the summer of 2007, over 1.5 square kilometres of sea ice were lost (3 times the surface area of France), breaking the previous record set in 2005 – a loss that no model had predicted so early! The Arctic Ocean plays a key role in the mass balance of sea ice. The water column is made up of different water masses that interact with each other by exchanging mass and heat. The layer known as the “halocline” plays a particularly important role. The halocline is a layer of cold water with steeply rising salinity located around 50 metres beneath the sea ice. However, little is known about the halocline today: scientists do not agree on how it was formed and its evolution is little documented. That is why I have chosen to focus on this water during the three years of my PhD.

AXA Fellowship

The AXA Research Fund is unique, in my view. Unlike other doctoral fellowships, which aim to fund a specific topic and then look for a PhD candidate, AXA bases its main selection criteria on the candidate and his or her motivations for pursuing a specific topic. This seems fair and logical to me, since a topic will not lead to much unless the PhD student devotes all of his or her enthusiasm and determination. Personally speaking, AXA has allowed me to pursue a goal that is important to me. It would not have been possible without them, and I thank them for giving me this opportunity.

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Sorbonne University