A Scientist's Life: Fiamma Straneo

Physical oceanographer studies interplay between Greenland's glaciers and a warming ocean

Physical oceanographer Fiamma Straneo was at Woods Hole Oceanographic Institution for 18 years before joining the faculty of Scripps Institution of Oceanography at the University of California San Diego on July 1, 2017. She received a Laurea cum Laude (MSc) in physics from the University of Milan and a PhD in physical oceanography from the University of Washington.

explorations now: What do you do for a living?

Fiamma Straneo: I am a physical oceanographer who studies the interaction of the polar oceans with other components of the climate system, especially ice sheets. A lot of the work I do is focused on understanding how glaciers interact with the ocean. It involves collecting data at the margins of glaciers or under floating parts of glaciers, as well as around large icebergs. We’re trying to understand whether the ocean in a warming planet is playing a role in triggering ice loss from ice sheets. This important process raises sea level and affects ocean circulation, changing the marine ecosystem and impacting the societies that rely on the ocean for food, transportation and other resources.

en: What are the main questions in your field?

FS: Over the last 20 years we’ve seen a lot of rapid changes, especially in the Greenland ice sheet that were unexpected and not predicted by models. In some ways, we’re playing catch-up. We know that ice sheets will lose ice and drive up sea level in a warming climate but what we need to understand is how quickly this will happen, and by what mechanisms it is happening. One of the big parts that we’re missing is the complicated interaction of ice and ocean.

In the beginning, the research I did was driven by trying to understand how the ocean is affecting the Greenland ice sheet. We knew the ocean was warming and wanted to understand if this warming ocean was speeding up loss in Greenland’s glaciers and sea-level rise but now we’re also seeing the impact of the ice melting on the ocean in terms of meltwater flowing into the ocean. This can affect ocean stratification and sea ice formation. It can affect ocean currents but also we find that it affects the marine ecosystem because there are a lot of nutrients that are being discharged with this meltwater. This is a new area of research that is interesting because we see a lot of changes happening around Greenland, both in circulation and in marine ecosystems.

One of the big things that changed about a decade ago is when we discovered that there were warm waters reaching the edge of Greenland’s glaciers. These are waters that have absorbed heat in the tropical Atlantic and are carried by the Gulf Stream and a whole system of currents up against the coast of Greenland and penetrating deep in these fjords, which are like large submerged valleys, and reaching the glaciers. All of a sudden we had a direct pathway for heat from tropical ocean to the margin of the Greenland ice sheet. That was like a new wiring of the climate system that we didn’t know about before.

We had been mostly unaware of what reached the glaciers. There had been no measurements in Greenland. No one was really interested and we naively thought that the cold waters that come down around Greenland from the Arctic Ocean were insulating the ice sheet from any influence from the Gulf Stream. So our new findings were really a turning point, this revolutionized the concept not just for modern climate change but also for understanding past climate change on longer time scales.

en:  What are the tools you use in field research?  

FS: Our research occurs in polar regions that are really hard to get to and hostile to work in. We badly need measurements that support our understanding. A lot of what I do involves trying to get observations from the margins of these crumbling glaciers so we can really get the physics and the dynamics understood and then feed that into the models that make predictions of sea-level rise. It involves working with any kind of platform that we think will work.

Our traditional means do not always work. I cannot get on a large research vessel and say “please drive up to that glacier” so what we do is try to use available resources by using local vessels and rely on the knowledge of people who have been navigating around these glaciers to hunt and fish for a long time. I work a lot on small boats and on helicopters, which allow me to fly above glaciers, find patches of open water, drop expendable probes and collect data that we otherwise wouldn’t be able to get. I use underwater and surface autonomous vehicles that you can send to icebergs to collect data without exposing humans to perils of calving icebergs. 

We deploy instruments that are anchored on the seafloor and rise above it. We never have something sticking out at the surface because icebergs would drag it. We try to be conservative, but we’ve had instruments that were placed hundreds of meters down destroyed by icebergs because these large icebergs are very, very deep. I probably lose about 25 percent of the gear I put in the ocean at any given time.

One of the tools we’ve been using to work at the edge of glaciers – which periodically calve off large pieces of ice so you don’t really want to send a human being there – is the JetYak. It’s a kayak with an engine that was developed to go fishing out on lakes. We put a whole series of instruments on it to measure water velocity and temperature. We can drive really close to the edge of the glacier and get measurements of the thin boundary layer between the ice and the ocean which we really can’t get at otherwise.

It’s very hard to find meltwater once it’s in the ocean. Ideally it would be colored blue or red and then we could just see it, but it’s not that way so we track these meltwaters in a number of ways. We can see the cooling of the ocean waters and the release of this freshwater and so we measure temperature and salinity and see how they change with respect to the waters that flow toward the glacier.

We’re also experimenting with tracer measurements. We’ve been using noble gases, which are inert gases that exchange mostly with the atmosphere and make their way to the base of the glacier in small air bubbles and are then released into ocean waters. They have different signatures depending on the depth and temperature at which bubbles popped and released the noble gases.We can then use these to reconstruct where the meltwater is. They’re wonderful fingerprints of meltwater. We’ve also been trying to measure sediment content or iron content as a means of tracking meltwater.

en: Why did you come to Scripps?

FS: Scripps is an amazing oceanographic institution. It’s a wonderful place to study some of the interdisciplinary problems that we’re dealing with today. One of the things that attracted me to Scripps was the possibility to interact with undergraduates as well as graduate students. It’s important to train these future generations in understanding the environment in quantitative and critical ways. It’s a really exciting place to be.

I think Scripps is in a wonderful phase. It’s really growing. It has a vision to try to address some of the big societally relevant questions that have to do with climate change and humans on the planet. I think it has done this by hiring a lot of young amazing people with a lot of energy and a lot of ideas in the last few years. One of the things I hope to do here is expand polar science research and increase public awareness of the polar region. We really need to train future generations to deal with changes that are happening at both poles that are having an impact on society. By studying what is happening at both poles, we can make a lot of progress in comparing these systems.

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