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GeoTalk: The life and death of an ocean – is the Atlantic Ocean on its way to closing?

GeoTalk: The life and death of an ocean – is the Atlantic Ocean on its way to closing?

Geotalk is a regular feature highlighting early career researchers and their work. Following the EGU General Assembly, we spoke to João Duarte, the winner of a 2017 Arne Richter Award for Outstanding Early Career Scientists.  João is a pioneer in his field. He has innovatively combined tectonic, marine geology and analogue modelling techniques to further our understanding of subduction initiation and wrench tectonics. Not only that, he is a keen science communicator who believes in fostering the next generation of Earth scientists.

Thank you for talking to us today! Could you introduce yourself and tell us a little more about your career path so far?

I am a geologist by training. I gained my undergraduate degree from the University of Lisbon and I stayed there to research geodynamics as part of my PhD which I finished in 2012. As I was coming to the end of writing up my thesis I moved to Monash University, in 2011, to start a postdoc.

Yes! I worked on my PhD and a postdoc at the same time, but I was only really finishing up. My thesis was almost ready. When I moved to Australia the defence was outstanding, but otherwise I was almost done.

My PhD thesis focused on the reactivation of the SW Iberian margin. It was the very first time I came across the problem of subduction initiation and that has become a big focus of my career to date.

My postdoc came to an end in 2015 and I moved back to Portugal and took up a position at the Faculty of Sciences of the University of Lisbon where I’ve started building my own research group [more on that later on in the interview].

I’ve always been passionate about science. It started when I was a kid, I’ve always been interested in popular science. My favourite writers are Isaac Asimov and Carl Sagan.

During EGU 2017, you received an Arne Richter Award for Outstanding Young Scientists for your work on subduction initiation and wrench tectonics. What brought you to study this particular field?

On the morning of the 1st of November 1755, All Saints Day, when many Portuguese citizens found themselves at church attending mass, one of the most powerful earthquakes ever document struck off the coast of Portugal, close to Lisbon.

It was gigantic, with an estimated magnitude (Mw) 8.5 or 9. It triggered three tsunami waves which travelled up the Tagus River, flooding Lisbon harbour and the downtown area. The waves reached the United Kingdom and spread across the Atlantic towards North America too.

The combined death toll as a result of the ground shaking, tsunamis and associated fires may have exceeded 100,000 people.

The event happened during the Enlightenment period, so many philosophers and visionaries rushed to try and understand the earthquake. Their information gathering efforts are really the beginning of modern seismology.

But the 1755 event wasn’t an isolated one. There was another powerful earthquake off the coast of Portugal 200 years later, in 1969. It registered a magnitude (Mw) of 7.8.

This earthquake coincided with the development of the theory of plate tectonics. While Wegener proposed the idea of continental drift in 1912, it wasn’t until the mid-1960s that the theory really took hold.

People knew by then that the margins of the plates along the Pacific were active – the area is famous for its powerful earthquakes, explosive volcanoes and high mountain ranges. Both the 2004 Indian Ocean and 2011 Thoku (Japan) earthquakes and tsunamis were triggered at active margins.

But the margins of the Atlantic are passive [where the plates are not actively colliding with or sinking below one another, so tectonic activity – such as earthquakes and volcanoes – is minimal]. So, it was really strange that we could have such high magnitude quakes around Portugal.

A large European project was put together to produce a map of the SW Iberian margin and the Holy Grail would be to locate the source of the 1755 quake. The core of my PhD was to compile all the ocean floor and sub-seafloor data and produce a new map of the main tectonic structures of the margin.

Tectonic map of the SW Iberia margin. In grey the deformation front of the GibraltarArc, in white the strike-slip fault associated with the Azores-Gibraltar fracture zone, and in yellow the new set of thrust faults that mark the reactivation of the margin (Duarte et al., 2013, Geology)

What did the new map reveal?

Already in the 70s and later in the late 90s, researchers started to wonder if this margin could be in a transition between passive to active: could an old passive margin be reactivated? If so, could this mean a new subduction zone is starting somewhere offshore Portugal?

The processes which lead a passive margin to become active were unclear and controversial. All the places where subduction is starting are linked to locations where plates are known to be converging already.

The occurrence of the high magnitude earthquakes, along with the fact that there is structural evidence (folding, faulting and independent tectonic blocks) of a subduction zone in the western Mediterranean (the Gibraltar Arc) suggested that it was possible that a new subduction system was forming in the SW Iberian margin.

The new ocean floor and seismic data revealed three active tectonic systems, which were included in the map. The map shows the margin is being reactivated and allowed identifying the mechanism by which it could happen: ‘Subduction invasion’ or ‘subduction infection’ (a term first introduced by Mueller and Phillips, 1991).

I’d like to stress though, that the map and its findings are the culmination of many years of work and ideas, by many people. My work simply connected all the dots to try to build a bigger picture.

So, what does ‘subduction infection and invasion’ involve?

Subduction zones, probably, don’t start spontaneously, but rather they are induced from locations where another subduction system (or an external force, such as  a collisional belt) already exists.

For example, if a narrow bridge of land connects an ocean (as is often the case) where subduction is active to one where the margins are passive. The active subduction zones from one can invade the passive margins and activate them. You see this in the other side of the Atlantic (where subduction zones have migrated from the Pacific), in the Scotia and the Lesser Antilles arcs.

We also know this has happened in past. But Iberia might be the only place where it is happening currently. And that is fascinating!

Earlier on you said that the ‘Holy Grail’ moment of the map would be if you could find the source of the 1755 earthquake. Did you?

No. Not entirely. The source of the earthquake is probably a complex fault, where multiple faults ruptured to generate the quake, not just one (as is commonly thought).

In your medal lecture at the General Assembly in 2017 (and in your papers) you allude to the fact that the reactivation of the SW Iberian margin has even bigger implications. You suggest that staring of subduction process in the arcs of the Atlantic could ultimately lead to the ocean closing altogether?

The Wilson cycle defines the lifecycle of an ocean: first it opens and spreads, then its passive margins founder and new subduction zones develop; finally, it consumes itself and closes.

So, the question is: if subduction zones are starting in the Atlantic will it eventually close?

There are a few things to consider:

The ocean floor age is limited. It seems that it has to start to disappear after about ~ 200 million years (the oldest oceanic lithosphere is ~ 270 million years old). Passive margins in the Earth history also had life spans of the order of ~ 200 Ma, suggesting that this may not be a coincidence. I suspect that there is a dynamic reason for this…

Most researchers agree that the next major oceanic basin which is set to close is the Pacific. The Americas (to the east) are moving towards East Asia and Australia at a rate of 3-4 cm yr-1, so it should close in roughly 300 million years.

We also know that the Atlantic has been opening for 200 million years already. If you believe that the closing of the Pacific indicates that continental masses have been slowly gliding towards each other to form the next supercontinent (a theory know as extroversion); then the Atlantic has to continue to open until the Pacific closes. This would mean that ocean floor rocks in the Atlantic would be very old (up to 500 million years old!) – highly unlikely given the oldest existing oceanic rocks are 270 million years old.

The map I made during my PhD showed that the Atlantic oceanic lithosphere is already starting to break-up and is weakened.

All the pieces combined, I think the most likely outcome is that the Pacific and the Atlantic will close at the same time. This scenario would require other oceanic basins to form, and that’s possible in the existing Indian Ocean and/or the Southern Ocean. Present-day continents would be brought together to form a new supercontinent, which we called Aurica.

Aurica – the hypothetical future supercontinent formed as the result of the simultaneous closure of the Atlantic and the Pacific oceans (Duarte et al., 2016, Geological Magazine).

If you take into consideration present-day plate velocities the supercontinent could be fully formed in approximately 300 million years’ time. We expect Aurica to be centred slightly north of the equator, with Australia and the Americas forming the core of the landmass.

With those findings, it is obvious why subduction has been a recurring theme in your career as a researcher. But what sparked your initial interest in geology and then tectonics in general?

I spent a lot of time outdoors as a kid. I was always curious and fascinated by the outdoor world. I joined the scouts when I was eight. We used to camp and explore caves by candle-light!

When I was 14 I took up speleology; there are lots of caves in the region I grew up in, in Portugal. As amateurs, my speleology group participated in archaeological and palaeontological work. The rocks in the region are mainly of Jurassic age and contain lots of fossils (including some really nice dinosaurs).

The outdoors became part of me.

I knew early on that I didn’t want a boaring job with lots of routine. I wanted a career that would allow me to discover new things.

Geology was the most obvious choice when picking a degree. I felt it offered me a great way to stay in touch with the other sciences too – physics via geophysics and biology through palaeontology.

In my 2nd year at university, I was invited to help in an analogue lab looking at problems in structural geology and geodynamics.

I was always attracted to the bigger picture. Plate tectonics unifies everything. I like how by studying tectonics you can link a lot of little things and then bring them together to look at the bigger picture.

What advice do you have for early career scientists?

When I found out about the award I was shocked because I wasn’t expecting it at all.

I always felt I wasn’t doing enough [in terms of research output]. I think that early career scientists are being pushed to limits that are unreasonable; the competition is intense. It’s not always obvious, but there is a lot of pressure to publish. But there are also a lot of very good people whose publication record doesn’t necessarily reflect their skill as a scientist.

The award made me realise I was probably doing enough!

Moving to Australia was KEY. Moving and creating collaborations with different people will make you unique. You don’t want to stay in the same institution. [By doing so] you become very linear. There are a number of schemes available (like Marie Curie and Erasmus) which allow you to move. Use these to the fullest. Moving allows you to see problems from different perspectives. And you will become more unique as a scientist.

There a lot of bright young scientist – never have we had so many – we are all unique, but you have to find the uniqueness in yourself. Most of all have fun. Do science for the right reasons and remember that people still recognise honest hard work (the award showed me that).

Interview by Laura Roberts, EGU Communications Officer.

References

Duarte, J. C., Rosas, F, M., Terrinha, P., Schellart W, P., Boutelier, D., Gutscher, M-A., and Ribeiro, A.,: Are subduction zones invading the Atlantic? Evidence from the southwest Iberia margin, GEOLOGY, 41, 8, 839–842, https://

Duarte, J. C., and Schellart W, P.,: Plate Boundaries and Natural Hazards, Geophysical Monograph, 219 (First Edition), ISBN: 978-1-119-05397–2, 2016

Duarte, J., Schellart, W., & Rosas, F.,: The future of Earth’s oceans: Consequences of subduction initiation in the Atlantic and implications for supercontinent formation, Geological Magazine, 1–14,  https://doi.org/10.1017/S0016756816000716, 2016.

Purdy, G.M.,: The Eastern End of the Azores-Gibraltar Plate Boundary, GJI, 43, 3, 973–1000, https://doi.org/10.1111/j.1365-246X.1975.tb06206.x, 1975

Mueller, S., Phillips, R, J.,: On The initiation of subduction, JGR, 96, B1, 651-665, https://doi.org/10.1029/90JB02237, 1991

Ribeiro, A., Cabral, J., Baptista, R., and Matias, L.,: Stress pattern in Portugal mainland and the adjacent Atlantic region, West Iberia, Tectonics, 15, 3, 641–659, https://doi.org/10.1029/95TC03683, 1996

 

 

 

 

 

GeoTalk: How are clouds born?

GeoTalk: How are clouds born?

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Federico Bianchi, a researcher based at University of Helsinki, working on understanding how clouds are born. Federico’s quest to find out has taken him from laboratory experiments at CERN, through to the high peaks of the Alps and to the clean air of the Himalayan mountains. His innovative experimental approach and impressive publication record, only three years out of his PhD, have been recognised with one of four Arne Richter Awards for Outstanding Early Career Scientists in 2017.

First, could you introduce yourself and tell us a little more about your career path so far?

I am an enthusiastic atmospheric chemist  with a passion for the mountains. My father introduced me to chemistry and my mother comes from the Alps. This mix is probably the reason why I ended up doing research at high altitude.

I studied chemistry at the University of Milan where I got my degree in 2009.  During my bachelor and master thesis I investigated atmospheric issues affecting the polluted Po’ Valley in Northern Italy and since then I have always  worked as an atmospheric chemist.

I did my PhD at the Paul Scherrer Institute in Switzerland where I mainly worked at the CLOUD experiment at CERN. After that, I used the acquired knowledge to study the same phenomena, first, at almost 4000 m in the heart of the Alps and later at the Everest Base Camp.

I did one year postdoc at the ETH in Zurich and now I have my own Fellowship paid by the Swiss National Science Foundation to conduct research at high altitude with the support of the University of Helsinki.

We are all intimately familiar with clouds. They come in all shapes and sizes and are bringers of shade, precipitation, and sometimes even extreme weather. But most of us are unlikely to have given much thought to how clouds are born. So, how does it actually happen?

We all know that the air is full of water vapor, however, this doesn’t mean that we have clouds all the time.

When air rises in the atmosphere it cools down and after reaching a certain humidity it will start to condense and form a cloud droplet. In order to form such a droplet the water vapor needs to condense on a cloud seed that is commonly known as a cloud condensation nuclei. Pure water droplets would require conditions that are not present in our atmosphere. Therefore, it is a good assumption to say that each cloud droplet contains a little seed.

At the upcoming General Assembly you’ll be giving a presentation highlighting your work on understanding how clouds form in the free troposphere. What is the free troposphere and how is your research different from other studies which also aim to understand how clouds form?

The troposphere, the lower part of the atmosphere, is subdivided in two different regions. The first is in contact with the Earth’s surface and is most affected by human activity. This one is called the planetary boundary layer, while the upper part is the so called free troposphere.

From several studies we know that a big fraction of the cloud seeds formed in the free troposphere are produced by a gas-to-particles conversion (homogeneous nucleation), where different molecules of unknown substances get together to form tiny particles. When the conditions are favourable they can grow into bigger sizes and potentially become cloud condensation nuclei.

In our research, we are the first ones to take state of the art instrumentation, that previously, had only been used in laboratory experiments or within the planetary boundary layer, to remote sites at high altitude.

Federico has taken state of the art instrumentation, that previously, had only been used in laboratory experiments or within the planetary boundary layer, to remote sites at high altitude. Credit: Federico Bianchi

At the General Assembly you plan on talking about how some of the processes you’ve identified in your research are potentially very interesting in order to understand the aerosol conditions in the pre-industrial era (a time period for when information is very scarce). Could you tell us a little more about that?

Aerosols are defined as solid or liquid particles suspended in a gas. They are very important because they can have an influence on the Earth’s climate, mainly by interacting with the solar radiation and cooling temperatures.

The human influence on the global warming estimated by the Intergovernmental Panel for Climate Change (known as the IPCC) is calculated based on a difference between the pre-industrial era climate indicators and the present day conditions. While we are starting to understand the aerosols present currently, in the atmosphere, we still know very little about the conditions before the industrial revolution.

For many years it has been thought that the atmosphere is able to produce new particles/aerosol only if sulphur dioxide (SO2) is present. This molecule is a vapor mainly emitted by combustion processes; which, prior to the industrial revolution was only present in the atmosphere at low concentrations.

For the first time, results from our CLOUD experiments, published last year,  proved that organic vapours emitted by trees, such as alpha-pinene, can also nucleate and form new particles, without the presence of SO2. In a parallel study, we also observed that pure organic nucleation can take place in the free troposphere.

We therefore have evidence that the presence of sulphur dioxide isn’t necessary to make such a mechanism possible. Finally, with all this new information, we are able to say that indeed, in the pre-industrial era the atmosphere was able to produce new particles (clouds seeds) by oxidation of vapors emitted by the vegetation.

Often, field work can be a very rewarding part of the research process, but traditional research papers have little room for relaying those experiences. What were the highlights of your time in the Himalayas and how does the experience compare to your time spent carrying out laboratory experiments?

Doing experiments in the heart of the Himalayas is rewarding. But life at such altitude is tough. Breathing, walking and thinking is made difficult by the lack of oxygen at high altitudes.

I have always been a scientists who enjoys spending time in the laboratory. For this reason I very much liked  the time I spent in CERN, although, sometimes it was quite stressful. Being part of such a large international collaboration and being able to actively do science was a major achievement for me. However, when I realized I could also do what I love in the mountains, I just couldn’t  stop myself from giving it a go.

The first experiment in the Alps was the appetizer for the amazing Himalayan experience. During this trip, we first travelled to Kathmandu, in Nepal. Then, we flew to Luckla (hailed as one of the scariest airport in the world) and we started our hiking experience, walking from Luckla (2800 m) up to the Everest Base Camp (5300 m). We reached the measurement site after a 6 days hike through Tibetan bridges, beautiful sherpa villages, freezing nights and sweaty days. For the whole time we were surrounded by the most beautiful mountains I have ever seen. The cultural element was even more interesting. Meeting new people from a totally different culture was the cherry on the cake.

However I have to admit that it was not always as easy as it sounds now. Life at such altitude is tough. It is difficult to breath, difficult to walk and to install the heavy instrumentation. In addition to that, the temperature in your room during nights goes well below zero degrees. The low oxygen doesn’t really help your thinking, especially we you need to troubleshoot your instrumentation. It happens often that after such journey, the instruments are not functioning properly.

I can say that, as a mountain and science lover, this was just amazing. Going on a field campaign is definitely the  best part of this beautiful job.

To finish the interview I wanted to talk about your career. Your undergraduate degree was in chemistry. Many early career scientists are faced with the option (or need) to change discipline at sometime throughout their studies or early stages of their career. How did you find the transition and what advice would you have for other considering the same?

As I said before, I studied chemistry and by the end of my degree my favourite subject moved to atmospheric chemistry. The atmosphere is a very complex system and in order to study it, we need a multidisciplinary approach. This forced me to learn several other aspects that I had never been in touch with before. Nowadays, I still define myself as a chemist, although my knowledge base is very varied.

I believe that for a young scientist it is very important to understand which are his or her strengths and being able to take advantage of them. For example, in my case, I have used my knowledge in chemistry and mass spectrometry to try to understand the complex atmospheric system.

Geotalk is a regular feature highlighting early career researchers and their work.

GeoTalk: Beatriz Gaite on why videos are a great tool for communicating your research to a broad audience

GeoTalk: Beatriz Gaite on why videos are a great tool for communicating your research to a broad audience

If you’ve not heard about our Communicate Your Science Video Competition before it gives early career scientists the chance to produce a video up-to-three-minutes long to share their research with the general public. The winning entry receives a free registration to the General Assembly the following year.

In this GeoTalk interview, Laura Roberts talks to Beatriz Gaite an early career scientist whose video on how recycling the noisy part of recordings made by seismometers can tells us important information about the Earth’s interior structure was voted as the winning entry of the 2016 Communicate Your Science Video Competition. Read on to hear about their top tips for filming a science video and what inspired them to use video to communicate their science in the first place.

Before we get started, could you introduce yourself and tell our readers a little more about your research?

I am a seismologist mainly studying the Earth structure. I did my PhD on Mexico and its vicinity using a novel approach developed in the last decade. Before, seismologists used to study earthquake signals to infer the inner structure, but now we can also study seismic ambient noise, which is everything on a seismic record… except the earthquake signals! This means we now analyse what  used to be thrown away, once considered useless. In this sense, it is like recycling. This has revolutionised the field and opened multiple applications, not only for imaging the Earth interior, but also for monitoring landslides, volcanoes or climate change effects.

Some of our readers may yet not be familiar with the competition, can you tell us a little more about it and what made you decide to take part in the competition?

Yes, the EGU video competition consists on explaining your research to a general audience through a three minute video. Once ready, you submit your video to EGU and disseminate it as much as possible to get people to vote for it . I decided to take part  because I was fascinated with the bunch of applications developed from seismic ambient noise and aware of the importance of communicating science to society. This cocktail of thoughts inspired me to create the video.

Watch Beatriz’s winning film, Subtle Whisper of the Earth

Had you filmed any science videos prior to producing ‘Subtle Whisper of the Earth’?

No, never. Only as a teenager I recorded some short, home-made videos for outdoor activities, but nothing related with science. However, in the production of Shubtle Whisper of the Earth I was helped by two professionals: Jordi Cortés, the journalist in charge of the communication at the Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, who filmed and edited the video, and Daniel García (@rocambloguesco), an Earth Sciences communicator who helped me with the script.

What inspired you to make a film about your research and submit the entry to the competition?

Since I finished my PhD I was thinking about making a documentary to show how seismic ambient noise was such a big evolution for seismology. Indeed, I already had some script ideas bubbling in my mind. Then, I found out  about the competition through the recently created communication department of my center and, after thinking about it I went for it. I thought it [the video competition} was a great opportunity to make my ideas real.

We can’t go into too much detail here, but how did you go about collecting the footage and turning it into a film?

First, I adapted my original ideas to the length of the video competition specifications. After several iterations, I got the main idea. In parallel, I thought on the story: I needed something common to people, like recycling. I made a script, then Daniel helped me to simplify it from the research realm to society, and I organised it in sequences, duration and film resources. All these steps were the most time-consuming part. Jordi and I organized the “field work” dividing the filming on indoor and outdoor. Since we organized the sequence planning in advance, it took us only one morning shooting indoors and one afternoon outdoors. Jordi’s experience behind the camera and in  production helped a lot to get the final video, but we only used user-level material and software for producing and editing.

What’s your top tip for aspiring science filmmakers?

Have a clear idea of the message you want to communicate. Also, you need a story to catch the attention of the audience. Once you have the idea and the story, the next step, how to visually express them, comes easily.

Beatriz preparing materials to be used in the making of her film. Credit: Jordi Cortés

Which part of the filming process did you enjoy the most?

I enjoyed the whole process, but especially two parts: first, the beginning of the creative process, thinking what, why, and how I wanted to communicate the story, imagining the screenshots in my mind. And second, shooting with Jordi was really fun, I enjoyed it a lot, it was like a game.

Would you recommend filmmaking as a way for scientist to reach out to a broad audience?

Sure! When I started I did not think that the video would reach as many people as it did. I was really happy when some friends told me ‘now we know what you do’. Even some colleagues told me that now they understood pretty well what we get from the seismic ambient noise. It is worth it. A short video is a good way to reach a broad audience globally. Being short, specific and visual are good ingredients to grab attention.

Would you recommend others taking part in the Communicate your Science Video Competition?

Yes, of course. It is an enjoyable exercise to communicate your research. The hardest part of the competition is the self-promotion to get votes, but that’s a different story 😉

Has this interview inspired you to go forth and produce a science video? The Communicate Your Science Video Competition is currently open for submissions.

If you are pre-registered to attend the General Assembly in April, go ahead and produce a video with scenes of you out in the field, or at the lab bench showing how to work out water chemistry; entries can also include cartoons, animations (including stop motion), or music videos, – you name it! To submit your video simply email it to Laura Roberts (networking@egu.eu) by 26 February 2017.

For more information about the competition take a look at this blog post. For inspiration, why not take a look at the finalist videos from the 2015 and 2016 editions? For more tips and tricks on how to make a video to communicate your research read an interview with vlogger extraordinaire Simon Clark. We also spoke to Zakaria Ghazoui, winner of the 2015 video competition to as his thoughts on how to make a great video.

GeoTalk: Using satellites to unravel the secrets of our planet’s polar regions

GeoTalk: Using satellites to unravel the secrets of our planet’s polar regions

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Bert Wouters, a polar scientist at the University of Utrecht, and winner of one of the 2016 Arne Richter Awards for Outstanding Young Scientists. At a time when the polar regions are facing increasing challenges resulting from climate change, understanding how they might respond to them is crucial. Bert’s PhD research using satellite data (from the GRACE mission) set a benchmark for the analysis and interpretation of data like it. As his career has advanced, Bert has made contributions to a number of fields within the polar sciences, from ice-sheet research, glacier and ice-cap mass-balance studies, through to ocean modeling and climate prediction. It is this notable breadth of knowledge, accompanied by an impressive publication record which makes Bert a worthy awardee.

First, could you introduce yourself and tell us a little more about your career path so far?

I was born and raised in Belgium, but moved to the Netherlands to study aerospace enginieering at the TU Delft when I was eightteen. During my PhD there, I focused on the use of satellite gravity data for climate science. Back then, the GRACE satellites had been in orbit for only a couple of years, and people were still learning how to handle and interpret this completely new set of data. The observations contained a lot more noise than expected before launch and one of the first things I did was to develop a method to remove this noise. Once we managed to do so, it opened up a whole new world. For the first time, we could track the movement of water mass on the Earth surface from month to month. These were certainly exciting times! My supervisor gave me the freedom to do pursue my own interests and I used the GRACE data to study many different topics, ranging from hydrology to oceanography and solid earth science. In the last year of my PhD, I focused on the cryosphere, which is still my main field of research.

After graduating, I did have the opportunity to continue in geodesy, but I felt it might be better for my overall development to step out of my comfort zone and move to a different field. I started a post-doc at the Dutch meteorological office (KNMI), with the aim of improving predictions of the Atlantic meridional overturning circulation. This is part of the global ocean conveyor belt and transports heat around the Earth. It has an important impact on the climate in the Atlantic region (think The day after tomorrow, minus the Hollywood drama) and my job was to predict its behaviour on decadal time scales using a global climate model. The first year was pretty though, but I learned a lot about the complexity of climate physics and numerical modeling, and I still profit from this experience today.

Meet Bert!

In 2012, I was awarded an ERC Marie Curie-Skłodowska fellowship and moved the University of Colorado in Boulder for 2 years to work with John Wahr. He was one of the founding fathers of the GRACE mission and a true giant in the field of geodesy. I had not met him before I started my fellowship, but he turned out to be not only a great scientist, but also one of the kindest and friendly persons I have ever met. I continued to refine my GRACE methods for monitoring of the cryosphere, but also started looking at different types of remote sensing data, in particular height measurements made by the Cryosat-2 altimetry mission.

This satellite had only been launched 2 years before and data was being released bit by bit.It gave me a great drive to be among a select group of people having a first look at these new observations. In the last year of my fellowship, I worked at the University of Bristol with Jonathan Bamber (the  EGU’s current  vice-president) to further refine the Cryosat-2 processing and combine it with the GRACE data. The combination of two independent measurements provides a powerful tool to map the ongoing changes in the cryosphere and yielded in some very exciting results.

Since November 2015, I’m a post-doc at the Institute for Marine and Atmospheric Research (IMAU, Utrecht University), renowned for their modelling of the regional processes (snowfall, melt, etcetera) on ice sheets and glaciers. Such models, together with in-situ observations, are indispensible to understand the changes we are seeing in the satellite data.

During EGU 2016, you gave a talk which focused on melting of glaciers and ice-caps in the North Atlantic. During the talk you spoke about the implication such melting might have on global sea level rise. Could you tell us a little more about your findings?

It’s a well known fact that the ice sheets of Greenland and Antarctica are losing ice. Studies about these regions usually receive a lot of attention from the media and general public, and rightly so: they contain a huge reservoir of ice and will be one of the major contributors to sea level rise in the coming centuries.

But we shouldn’t forget about the smaller ice caps and glaciers in other parts of the world. Many of them are located in regions which are experiencing rapid warming and because of their small size and the delicate balance between snowfall and melt that shapes them, they are extremely vulnerable to changes in the local climate. The GRACE and Cryosat-2 data show that glaciers in the North-Atlantic region currently contribute as much to sea-level rise as the Antarctic ice sheet and will continue to do so in the future. In fact, models indicate that some of the ice caps are already beyond a point of no return and that glaciers and ice caps will be one of the major sources of sea level rise in the coming decades.

Why have the glaciers and ice-caps of the North  Atlantic region received such little attention, at least until now, considering the potentially large impact their melting can have on global sea levels?

Tthe Devon Ice Cap, located in eastern Devon Island, Nunavut, Canada is one of the North Atlantic region ice-caps which have received little attention.

Well, of course I’m not the first to study these glaciers and ice caps. In fact, some individual glaciers have been monitored for over a hundred years. These records are extremely valuable and vital for validating and interpreting satellite observations, and already showed that many glaciers are retreating.

However, taking in-situ measurements on a glacier is a challenging job, and often expensive, so these observations are generally made on small glaciers, which tend to be located in easily accessible locations with a maritime climate.  This means that the few hundreds of glaciers that are monitored on a regular basis are not necessarily representative for the roughly 200 000 glaciers world wide. We really need satellite observations for that. So maybe one of the reasons that they have received little attention is because we just didn’t know how bad things are until recently.

Another reason is that their big brothers, Antarctica and Greenland, pose a huge threat, too, especially when considering longer, millenial, time scales. There’s only so much research funding out there, so in a way it makes sense that the scientific community focused on this first when global warming came into the picture.

A common theme throughout your research has been using satellite data and geodesy to unravel the secrets of our planet’s polar regions and oceans. What attracted you to this particular branch of the Earth sciences?

To be honest, I ended up in this field more or less haphazardly, it wasn’t part of a grand master plan I had when I started university. Back then, my main interest lay in aerodynamics, but by the time I had to choose a topic for my master thesis, I couldn’t imagine myself working on that for the rest of my life. When one of my supervisors suggested I work on remote sensing of sea level rise, it felt as if it was the right thing to do and that’s how it all started.
Having said that, as a kid, I was fascinated by two things: science, inspired by a nutty professor in my favorite comic books, and nature (around the age of six, I started a club together with a friend to save the planet) and in a way I’m combining these two things in my present job. So maybe I was just destined for this after all…

Also, at a time where travel has almost become a commodity to most people, I find it fascinating that there are still places on Earth where no one has ever set foot and which we can only study using remote sensing. Its very intriguing and almost a privilige to be able to map these places at an ever increasing level of detail, especially with all the dramatic changes that are now going on in the polar regions.

Quoting the late Gordon Hamilton: “Every time I open up a satellite image the potential is there for something astonishing to have happened since the last time I looked.” That sums up pretty well what makes this job so exciting, I think.

The Grace satellites in action. Credit: NASA JPL.

It’s clear that satellite data is invaluable when it comes to understanding changes on our planet. How do the GRACE and Cyosat satellites help in that effort?

GRACE is the only mission that can directly weigh the ice caps and glaciers, but it has a very coarse resolution, typically a few hundreds of kilometres. It helps to track the changes in ice mass on a regional scale, but that’s far too low to identify individual ice caps or glaciers. Cryosat-2 allows us to do so, but it measures height changes, and certain assumptions need to be made to translate this to mass changes, which can be verified against the GRACE observations. So these two missions nicely compliment each other.

Thank you for talking to us Bert. We’ll round-off this interview with a final question about careers. As a researcher who has made huge advances in this field, what advice would you give to someone who wants to pursue research in the field of geodesy and remote sensing, particularly when it comes to focusing on the planet’s polar regions?

Keep an open mind and don’t be afraid to stray outside your  own research field! Everything is connected in climate science, the polar regions aren’t an isolated system and to understand what’s going on and how to optimally use the satellite data, a basic knowledge of climate physics helps a lot.

Many problems we’re facing in geodesy and remote sensing also pop up in other fields, in a slightly different way and often other people have already found a solution to your problem. For example, to filter out the noise in the GRACE data, I used a method that’s commonly applied in atmospheric science. My second advice would be: collaborate! The problems we’re facing are so complex that it’s impossible to solve everything on your own. Interact with other scientists, within and outside your own field, it pays off.

And don’t be afraid to share your data and preliminary results with others. There’s a lot of pressure, especially on starting scientists, to publish as much as possible which sometimes makes it tempting to keep your data to yourself. But many times, other people have that piece of data that would make your study so much more interesting. And if someone else publishes a paper on something you’re working on, don’t hold any grudges, but try to find a different angle to it and do better. There’s some much to study, and science shouldn’t be about competition, but about collaboration.

Geotalk is a regular feature highlighting early career researchers and their work.

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