GeoLog

Arne Richter Award for Outstanding Young Scientists

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: 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.

GeoTalk: Deciphering the mysteries of the Mediterranean Sea with Katrin Schroeder

GeoTalk: Deciphering the mysteries of the Mediterranean Sea with Katrin Schroeder

Geotalk is a regular feature highlighting early career researchers and their work. Following the EGU General Assembly, we spoke to Katrin Schroeder, the winner of a 2015 Arne Richter Award for Outstanding Young Scientists.

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

Meet Katrin!

Meet Katrin! Credit: Katrin Schroeder

I am a physical oceanographer with a background in environmental science. I did my studies at the University of Venice(Italy) and in collaboration with the Institute for Marine Sciences of the Italian National Research Council (CNR-ISMAR). I started off working on biogeochemical cycles in coastal waters and then moved to the larger scale and to the physics of ocean dynamics in the open sea, trying also to combine physical and biogeochemical oceanography. In 2006 I started to work at CNR ISMAR in La Spezia, on the shore of the Ligurian Sea, in a beautiful office with sea view, reminding me every morning how lucky I was to have my job. I finally got a permanent position at CNR ISMAR in Venice in 2011. This period was characterized by intense learning, participation to workshops, summer schools and conferences, prolonged visits at the National Oceanography Centre in Southampton, writing my PhD thesis and papers, and participating in oceanographic cruises of the Mediterranean Sea, 1-2 months per year. I slowed down this rhythm recently, but just a bit, after the birth of my first son (now 3 years old), and my two twin boys (now 1 year old). I am looking forward to go back out to sea again soon.

What sparked your interest in oceanography?

At the beginning it was more or less by chance that I started to work on the Mediterranean Sea, and became a physical oceanographer, since after several applications to various marine and environmental institutes in 2004 I got my first fellowship at the Unit for Marine Research (ENEA in La Spezia). After my first oceanographic cruise, in 2005, in the Western Mediterranean Sea, I knew that that was “my” job. At that time there was no internet on research vessels and offshore the mobile phones served only to help you to wake up in time for your next shift in the middle of the night (these vessels operate 24/24 hours): you were completely in another dimension for days or weeks, without any contact with the “outside world”, working hard and in close contact with a limited number of persons. For me, that was great. What I really love in my job as a sea-going physical oceanographer is the alternation between “thinking” phases (in the office, in front of a pc) and “operating” phases (the cruise, the pre and post activities).

Much of your research focuses on the Mediterranean Sea, what makes it such an ideal candidate for oceanographic studies?

The Mediterranean has a number of valuable advantages (besides, CNR ISMAR being on its door steps). It is in many ways a miniature ocean and a natural laboratory for climatic studies: it has deep water formation varying on interannual time scales and a well-defined overturning circulation, and there are distinct surface, intermediate and deep water masses circulating between the western and the eastern basin. What makes the Mediterranean particularly useful for climate change studies is that its time scale is much shorter than for the global ocean, with a turnover time of roughly 60 years compared with more than 500 years for the global ocean. Changes can happen faster, on the time scale of a human lifetime.

During EGU 2015, you received the Arne Richter Award for Outstanding Young Scientists for your work on experimental oceanography, where you have contributed original ideas on the understanding of the formation and spreading of Mediterranean deep waters. Could you tell us a bit more about your research in this area?

In the deep layers of the Western Mediterranean an almost constant trend towards higher salinity and temperature has been observed since the ‘50s. More recent observations evidenced an acceleration of this tendency. An alteration of the water mass vertical distribution, associated with an abrupt temperature and salinity increase has been observed. In particular, since March 2005 large volumes of new bottom water has formed in the northwestern Mediterranean Sea. Remarkably this new bottom water is warmer and saltier than the old deep waters so it has become an easily recognized water mass when temperature and salinity profiles are made through the water column. Since its formation, this new bottom water has spread out into the western Mediterranean so that now it forms a bottom layer of warm salty water up to 1000 m thick throughout the western Mediterranean basin. The new bottom water has provided a natural tracer release experiment for understanding how bottom water fills the basin. The processes of deep water formation, the filling of the western Mediterranean with the new deep waters formed in the north, and the mixing between old and new deep waters are keys to understand how the Mediterranean is changing under changing climate conditions. An important open issue is how the old and new deep waters mix, on what time scale and by what processes, and in particular to quantify the role of turbulent mixing in the overall diffuse upwelling, the returning branch of the vertical thermohaline circulation.

The possible impacts these changes could have on a global scale are still an open issue.

oceans

Mediterranean thermohaline circulation (modified by Loic Houpert from Tsimplis et al., 2006): AW=Atlantic Water, LIW=Levantine Intermediate Water, WMDW=Western Mediterranean Deep Water, EMDW=Eastern Mediterranean Deep Water. Credit: Katrin Schroeder

With my team we observed the anomaly thanks to repeated oceanographic cruises in the Western Mediterranean. We started to publish about the deep water formation event in the north-western Mediterranean in 2006 (Schroeder et al., 2006, GRL). The event was extraordinary for its large volume of warmer and thermohaline properties of the deep water produced during the severe winter of 2004/2005. I have explored the causes of this event, tracing its origin back to the Eastern Mediterranean, from where increased amounts of heat and salt were imported to the Western Mediterranean and I have examined with new observations the spreading of the new water as a transient tracer through the western Mediterranean.

How does bottom water form, exactly and how is it different to other water in Mediterranean?

Bottom water forms in some specific regions worldwide, and few of them are also located in the Mediterranean Sea. Deep waters are “formed” (or we should rather say “transformed” from surface and intermediate water masses) where the air temperatures are cold and where the salinity of the surface waters are relatively high. The combinations of salinity and cold temperatures make the water denser and cause it to sink to the bottom. Its formation may occur either in the open ocean by deep convection or on the continental shelves by a process called dense shelf water cascading. In the Mediterranean both phenomena are present: in the Gulf of Lion (north-western Mediterranean Sea), in the Adriatic Sea and in the Aegean Sea. This sites maintain the Mediterranean thermohaline circulation in motion and, ventilating the deep layers, provide fresh oxygen to the deep water ecosystems. The Mediterranean also hosts a surface water mass, which comes directly from the Atlantic Ocean and circulates through the whole basin, gradually increasing its density because of the strong evaporation that takes place in the region. In the Mediterranean intermediate water masses are also formed, with processes that are similar to the bottom water formation, but in different locations and with density characteristics that do not allow these water masses to sink to the very bottom.

Earlier, you mentioned that the Mediterranean is useful for climate change studies due to having a much quicker turnover than the larger oceans. Can you describe an example of just how the study of the Mediterranean has been useful in this way?

The most important example is the in depth investigation of the process of deep water formation, which is an essential component of the global ocean conveyor belt, and sustains the present climatic state. The process happens mostly at high latitudes, but also in the north-western Mediterranean Sea on much smaller scales. Observations of the processes involved in open-ocean deep convection began with the now classical Mediterranean Ocean Convection (MEDOC) experiment in the Gulf of Lion [MEDOC Group, 1970]. With respect to high latitude sites, the Mediterranean site had the advantages of being less expensive to investigate, given an easier access with oceanographic vessels, due to its closeness to the coast and oceanographic institutes, of offering to milder winter conditions (season during which the dense water formation takes place) facilitating operations at sea. It is also very likely that studies about process related to ocean acidification and carbon sequestration as a consequence of dense water formation will be more feasible in the Mediterranean Sea.

What advice do you have for early career scientists on how achieve a good work/life balance?

Well, this is strongly dependent on the specific conditions you have in your life and it depends on your priorities: I have strong support from my family, I have the possibility to have a kindergarten close to our home with an affordable fee (this is the most important thing I must say!), and I have made the choice to let the household behind ….and I do not iron!

Finally, could you tell us a bit about your future research plans?

Staying very general, I am starting to follow a path of a higher interdisciplinary in oceanographic disciplines, trying to enforce the dialogue between us, physical oceanographers, and biological, microbiological and chemical oceanographers, as well as with climatologists and meteorologists.

References

Schroeder K., Gasparini G.P., Tangherlini M., Astraldi M.: Deep and Intermediate Water in the Western Mediterranean under the influence of the Eastern Mediterranean Transient. Geophys. Res. Lett. 33, doi: 10.1028/2006GL02712