One UEA PhD student’s journey to deep within the Arctic circle

In the summer of 2020, when much of the world was going in and out of lockdown, an international team of scientists were drifting with the Arctic ice onboard a German icebreaker, the RV Polarstern. UEA EnvEast-funded PhD student Elise Droste was among them, there to measure the Arctic Ocean’s capacity for absorbing carbon, and understand how this will change as a result of global warming.

From sea ice to seabed, 4km below, Elise’s story is one of polar bear spotters, precarious sampling sites, and vital international collaboration in the fight against climate change.

The first time I saw sea ice was during an Antarctic expedition to the Weddell Sea. I was mesmerised by it. Up to that point, sea ice had only been something I had read and heard about. I’d never dreamed of being able to see it, let alone get close to it, and study it. But being there, seeing it, was an exhilarating experience. I can still hear the breaking of the ice as we pushed our way through, the whole ship rumbling.

So when the opportunity to join the MOSAiC expedition, which was being spearheaded by the Alfred Wegener Institute, came along, I jumped at the chance – it sounded like an epic scientific adventure. Not only would it take me to the Arctic for the first time, but I knew my research would fit perfectly with the aims of the expedition. I was able to grasp this opportunity thanks to the unwavering support from my supervisors Dorothee Bakker, in the School of Environmental Sciences at UEA, and Mario Hoppema, and the openness of the MOSAiC team, especially Markus Rex and Allison Fong.  

For decades we’ve known we are making a ‘discernible human influence on global climate.’ Carbon dioxide is accumulating in the atmosphere as a result of anthropogenic activities and the current rate of emissions is so fast that the natural system cannot maintain its previous balance. The result? The climate is rapidly changing.

The oceans, and especially the polar oceans, play an important role in sustaining this natural balance. They absorb a lot of the carbon dioxide (CO₂), but the amount and rate at which they absorb greenhouse gases is not constant in time or space.

It’s important that we are able to accurately quantify the capacity of the polar oceans to take up CO₂ and predict how it will change. This will help us understand what our climate will look like in the future and what the effect will be on ecology, biodiversity, and the human population. It’s important to understand the drivers and processes that affect the carbonate chemistry of the seawater on all kinds of time scales, including seasonal and interannual time scales. To do this we need to conduct research throughout entire years, from atmosphere to seabed, and this is where MOSAiC comes in.

Life onboard

Working on the sea ice was incredible. I often found myself lost in my work, wiggling my toes to maintain blood circulation and trying to keep my hands warm, and then remembering that I was standing on sea ice that was about a metre thick in the middle of an ocean, with over 4 km of water beneath me.

It’s a very dynamic place to work. Ridges form under pressure and leads can open when you least expect it. Their sudden appearance destroyed and altered our sampling sites, and sometimes made them inaccessible altogether.

And then of course there are the polar bears. If one of the polar bear guards spotted a bear all scientific activities would immediately be suspended, no matter whether you were in the middle of sample collection.

We were working in the home of the polar bears, so when they appear, we move back to the ship and wait till they leave. I was a polar bear guard on several occasions – an epic way of contributing to science.

Life onboard was intense, but intense in the sense that I wanted to make the most out of every minute; intense in a very positive way. There was so much beauty around me and I wanted to make sure that I could take it all in, while doing the work required of Team ECO, making sure I was collecting the samples I needed for my project and that of others, learning as much as I could from the other scientists, and just trying to do the best science I could.

I personally never felt isolated when at sea and my favourite aspect of being onboard was spending time with the people and marvelling at the ocean, sea ice, and wildlife together.

You get to know the people really well; you have to work closely together, coordinate scientific activities, and agree on the planning. Working on a ship can also be very emotionally challenging, especially when you are sleep deprived and stressed. But the support of the people around you is amazing. People are considerate, tolerant, and empathetic. It’s an approach or mental state that you need to adopt when going to sea, because you can’t run away from problems or challenges. And both scientists and crew also need a bit of fun, so people are always keen to organise social events.

A word of advice: always bring a lot of chocolate on a ship, and beware the fresh-food-fantasies! They become very prominent at the end of an expedition. We stopped by Svalbard on our way back from the high Arctic and took on a delivery of fresh vegetables. Fresh tomatoes and cucumber never tasted so good!

The energy budget 'flips'

One of the objectives of our leg was to capture that moment when the energy budget would ‘flip’. This balance of in-coming and out-going radiation – the surface radiation budget – determines how much energy a surface absorbs and how much it reflects/emits. This in turn drives sea ice melt or growth.

During the summer, the radiative balance is so that the surface is absorbing more energy than it is reflecting, enhancing sea ice melt. In the winter, it’s the other way around: the sea ice reflects more radiative energy than it absorbs, enabling more sea ice growth. The switch between the two happens quite rapidly at the end of the summer season and we often refer to it as the onset of freeze-up of the Arctic for that year. We wanted to capture this moment in our observations to plot out the context of what happens to the Arctic Ocean as it plummets into its icy winter.

At the beginning of our leg, the sea ice was covered with beautiful blue melt ponds. By the end, everything was white; melt ponds were freezing and there was a layer of snow covering the ice floes. The landscape was changing in terms of its physical condition, implicating the biogeochemistry of all spheres. The amazing thing was that we could see this happening with our own eyes. It’s incredible to be able to link the changes in the numbers of our measurements to a visual experience. It was absolutely stunning.

Being able to witness this moment (both in experience and in the measurements) is a very important part in understanding the annual cycle within the Arctic.