GeoLog

Arne Richter Award for Outstanding Early Career Scientists

GeoTalk: To understand how ice sheets flow, look at the bedrock below

GeoTalk: To understand how ice sheets flow, look at the bedrock below

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Mathieu Morlighem, an associate professor of Earth System Science at the University of California, Irvine who uses models to better understand ongoing changes in the Cryosphere. At the General Assembly he was the recipient of a 2018 Arne Richter Award for Outstanding Early Career Scientists.  

Could you start by introducing yourself and telling us a little more about your career path so far?

Mathieu Morlighem (Credit: Mathieu Morlighem)

I am an associate professor at the University of California Irvine (UCI), in the department of Earth System Science. My current research focuses on better understanding and explaining ongoing changes in Greenland and Antarctica using numerical modelling.

I actually started glaciology by accident… I was trained as an engineer, at Ecole Centrale Paris in France, and was interested in aeronautics and space research. I contacted someone at the NASA Jet Propulsion Laboratory (JPL) in the US to do a six-month internship at the end of my master’s degree, thinking that I would be designing spacecrafts. This person was actually a famous glaciologist (Eric Rignot), which I did not know. He explained that I was knocking on the wrong door, but that he was looking for students to build a new generation ice sheet model. I decided to accept this offer and worked on developing a new ice sheet model (ISSM) from scratch.

Even though this was not what I was anticipating as a career path, I truly loved this experience. My initial six-month internship became a PhD, and I then moved to UCI as a project scientist, before getting a faculty position two years later. Looking back, I feel incredibly lucky to have seized that opportunity. I came to the right place, at the right time, surrounded by wonderful people.

This year you received an Arne Richter Award for Outstanding Early Career Scientists for your innovative research in ice-sheet modelling. Could you give us a quick summary of your work in this area?

The Earth’s ice sheets are losing mass at an increasing rate, causing sea levels to rise, and we still don’t know how quickly they could change over the coming centuries. It is a big uncertainty in sea level rise projections and the only way to reduce this uncertainty is to improve ice flow models, which would help policy makers in terms of coastal planning or choosing mitigation strategies.

I am interested in understanding the interactions of ice and climate by combining state-of-the-art numerical modelling with data collected by satellite and airplanes (remote sensing) or directly on-site (in situ).  Modelling ice sheet flow at the scale of Greenland and Antarctica remains scientifically and technically challenging. Important processes are still poorly understood or missing in models so we have a lot to do.

I have been developing the UCI/JPL Ice Sheet System Model, a new generation, open source, high-resolution, higher-order physics ice sheet model with two colleagues at the Jet Propulsion Laboratory over the past 10 years. I am still actively developing ISSM and it is the primary tool of my research.

More specifically, I am working on improving our understanding of ice sheet dynamics and the interactions between the ice and the other components of the Earth system, as well as improving current data assimilation capability to correctly initialize ice sheet models and capture current trends. My work also involves improving our knowledge of the topography of Greenland and Antarctica’s bedrock (through the development of new algorithms and datasets). Knowing the shape of the ground beneath the two ice sheets is key for understanding how an ice sheet’s grounding line (the point where floating ice meets bedrock) changes and how quickly chunks of ice will break from the sheet, also known as calving.

Steensby Glacier flows around a sharp bend in a deep canyon. (Credit: NASA/ Michael Studinger)

At the General Assembly, you presented a new, comprehensive map of Greenland’s bedrock topography beneath its ice and the surrounding ocean’s depths. What is the importance of this kind of information for scientists?

I ended up working on developing this new map because we could not make any reliable simulations with the bedrock maps that were available a few years ago: they were missing key features, such as deep fjords that extend 10s of km under the ice sheet, ridges that stabilize the retreat, underwater sills (that act as sea floor barriers) that may block warm ocean waters at depth from interacting with the ice, etc.

Subglacial bed topography is probably the most important input parameter in an ice sheet model and remains challenging to measure. The bed controls the flow of ice and its discharge into the ocean through a set of narrow valleys occupied by outlet glaciers. I am hoping that the new product that I developed, called BedMachine, will help reduce the uncertainty in numerical models, and help explain current trends.

3D view of the bed topography and ocean bathymetry of the Greenland Ice Sheet from BedMachine v3 (Credit: Peter Fretwell, BAS)

How did you and your colleagues create this map, and how does it compare to previous models?

The key ingredient in this map, is that a lot of it is based on physics instead of a simple “blind” interpolation. Bedrock elevation is measured by airborne radars, which send electromagnetic pulses into the Earth’s immediate sub-surface and collect information on how this energy is reflected back. By analyzing the echo of the electromagnetic wave, we can determine the ice thickness along the radar’s flight lines. Unfortunately, we cannot determine the topography away from these lines and the bed needs to be interpolated between these flight lines in order to provide complete maps.

During my PhD, I developed a new method to infer the bed topography beneath the ice sheets at high resolution based on the conservation of mass and optimization algorithms. Instead of relying solely on bedrock measurements, I combine them with data on ice flow speed that we get from satellite observations, how much snow falls onto the ice sheet and how much melts, as well as how quickly the ice is thinning or thickening. I then use the principle of conservation of mass to map the bed between flight lines. This method is not free of error, of course! But it does capture features that could not be detected with other existing mapping techniques.

3D view of the ocean bathymetry and ice sheet speed (yellow/red) of Greenland’s Northwest coast (Credit: Mathieu Morlighem, UCI)

What are some of the largest discoveries that have been made with this model? 

Looking at the bed topography alone, we found that many fjords beneath the ice, all around Greenland, extend for 10s and 100s of kilometers in some cases and remain below sea level. Scientists had previously thought some years ago that the glaciers would not have to retreat much to reach higher ground, subsequently avoiding additional ice melt from exposure to warmer ocean currents. However, with this new description of the bed under the ice sheet, we see that this is not true. Many glaciers will not detach from the ocean any time soon, and so the ice sheet is more vulnerable to ice melt than we thought.

More recently, a team of geologists in Denmark discovered a meteorite impact crater hidden underneath the ice sheet! I initially thought that it was an artifact of the map, but it is actually a very real feature.

More importantly maybe, this map has been developed by an ice sheet modeller, for ice sheet modellers, in order to improve the reliability of numerical simulations. There are still many places where it has to be improved, but the models are now really starting to look promising: we not only understand the variability in changes in ice dynamics and retreat all around the ice sheet thanks to this map, we are now able to model it! We still have a long way to go, but it is an exciting time to be in this field.

Interview by Olivia Trani, EGU Communications Officer

GeoTalk: How will large Icelandic eruptions affect us and our environment?

GeoTalk: How will large Icelandic eruptions affect us and our environment?

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Anja Schmidt, an interdisciplinary researcher at the University of Cambridge who draws from atmospheric science, climate modelling, and volcanology to better understand the environmental impact of volcanic eruptions. She is also the winner of a 2018 Arne Richter Award for Outstanding Early Career Scientists. You can find her on twitter at @volcanofile. 

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

I was born and raised in Leipzig, Germany. I started my career completing an apprenticeship as an IT system engineer with the engineering company Siemens. I then decided to combine my interests in geology and IT by studying geology and palaeontology (with minors in Computing/IT and Geophysics) at the University of Leipzig in Germany. As part of my degree programme, I also studied at the University of Leeds’ School of Earth and Environment as an exchange student. I liked studying there so much I ended up returning to Leeds for a PhD.

My PhD on the atmospheric and environmental impacts of tropospheric volcanic aerosol again combined my interests in computing and volcanology, although I had to educate myself in atmospheric physics and chemistry, which wasn’t easy to begin with. However, I was embedded in a diverse,   supportive research group with excellent supervision, which eased the transition from being a geologist to becoming a cross between an atmospheric scientist and a volcanologist.

Initially, being neither one nor the other made me nervous. My supervisors and mentors all had rather straightforward career paths, whereas I was thought of as an atmospheric scientist when I presented my research in front of volcanologists and as a volcanologist when I presented to atmospheric scientists.

After my PhD, I spent just under 2 years at one post-doc before securing an independent research fellowship at the University of Leeds. The first year of total independence and responsibility as principle investigator was very challenging, but after a while I began to appreciate the benefits of the situation. I also really started to embrace the fact that I would always sit between the disciplines. I spent my summers in the United States at the National Centre for Atmospheric Research, helping them to build up their capability to simulate volcanic eruptions in their climate model. These research visits had a major impact on my career as they generated a lot of new research ideas, opened up opportunities and strengthened my network of collaborators greatly.

I considered myself settled when, shortly before the end of my fellowship, a lectureship came up. It had the word ‘interdisciplinary’ in its title and I simply couldn’t resist. Since September 2017, I have been an interdisciplinary lecturer at the University of Cambridge in the UK.

At this year’s General Assembly, you will receive an Arne Richter Award for Outstanding Early Career Scientists for your work on the environmental impacts of volcanic eruptions. What brought you to study this particular field?

I have always been fascinated by volcanic eruptions, but my first active volcano viewing wasn’t until college, where I had to chance to travel to Stromboli, a volcanic island off the coast of Sicily. While studying at the University of Leipzig, I used every opportunity to join field trips to volcanoes. I ended up spending 10 weeks in Naples, Italy to work with Giovanni Chiodini, a researcher from the National Institute of Geophysics and Volcanology in Rome, and his team on CO2 degassing from soils at the Solfatara volcano. Later on I was awarded a scholarship from the University of Leeds, which allowed me to delve deeper into the subject, although I ended up learning as much about atmospheric science and computer modelling as about volcanology.

Anja in front of the 2010 Fimmvörðuháls eruption in Iceland. Fimmvörðuháls was the pre-cursor eruption to Eyjafjallajökull. Credit: Anja Schmidt.

My PhD work focused on Icelandic volcanism and its potential effects on the atmosphere as well as society. In 2010, during the 3rd year of my PhD studies, Eyjafjallajökull erupted in Iceland. While an eruption like this and its impacts did not really come as a surprise to a volcanologist, I personally considered it a game-changer for my career. I had an opportunity to witness the pre-cursor eruption in Iceland and present my research. Within a matter of months, interest in my work increased. I even started to advise UK government officials on the risks and hazards of volcanic eruptions in Iceland.

In August 2014, an effusive eruption started at the Holuhraun lava field in Iceland. To this date, analysing field measurements and satellite data of the site and modelling simulations keeps me busy. Many of my senior colleagues told me that there is one event or eruption that defined their careers; for me that’s the 2014-2015 Holuhraun eruption.

At the General Assembly you also plan to talk about your work on volcanic sulphur emissions and how these emissions can alter our atmosphere as well as potentially affect human health in Europe. Could you tell us a little more about this research?

On average, there is one volcanic eruption every three to five years in Iceland. The geological record in Iceland also reveals that sulphur-rich and long-lasting volcanic eruptions, similar to Iceland’s Laki eruption in 1783-1784, occur once every 200 to 500 years. Sulphur dioxide and sulphate particles produced by volcanic eruptions can have detrimental effects on air quality and human health. Historical records from the 1780s imply that the Laki eruption caused severe environmental stress and contributed to spikes in mortality rates far beyond the shores of Iceland. While these long-lasting eruptions occur much less frequently than more typical short-duration explosive eruptions (like Grímsvötn 2011), they are classified as ‘high-impact’ events.

I was always interested in investigating how a similar magnitude eruption like Laki’s would affect modern society. By combining a global aerosol microphysics model with volcanological datasets and epidemiological evidence, I led a cross-disciplinary study to quantify the impact that a future Laki-type eruption would have on air quality and human health in Europe today.

Our work suggests that such an eruption could significantly degrade air quality over Europe for up to 12 months, effectively doubling the concentrations of small-sized airborne particles in the atmosphere during the first three months of the eruption. Drawing from the epidemiological literature on human response to air pollution, I showed that up to 140,000 cardiopulmonary fatalities could occur across Europe due to such an eruption, a figure that exceeds the annual mortality from seasonal influenza in Europe.

In January 2012, this discovery was used by the UK government as contributing evidence for including large-magnitude effusive Icelandic eruptions to the UK National Risk Register. This will help to mitigate the societal impacts of future eruptions through contingency planning.

Anja and her colleague Evgenia Ilyinskaya from the University of Leeds carrying out measurements during the 2014-2015 Holuhraun eruption in Iceland. Credit: Njáll Fannar Reynisson.

Since then, we have done more work on smaller-magnitude effusive eruptions such as the 2014-2015 Holuhraun eruption in Iceland, showing that this eruption resulted in short-lived volcanic air pollution episodes across central and northern Europe and longer-lasting and more complex pollution episodes in Iceland itself.

Something that you’ve touched on throughout this interview are the challenges of ‘sitting between the disciplines.’ From your experience, what has helped you address these issues throughout your career?

Indeed, it is often challenging to sit between the disciplines, but it can also be very rewarding. It helps to ignore boundaries between disciplines. I also tend to read a lot and very widely to get an idea of key concepts and issues in specific fields. In addition, I think collaboration and a willingness to challenge yourself are key if you want to make progress and break traditional disciplinary boundaries.

Anja, thank you so much for speaking to us about your research and career path. Before I let you go, what advice do you have for aspiring scientists? 

Be curious and never hesitate to ask a lot questions, no matter how ‘stupid’ or basic they may seem to you. The latter is particularly true when it comes to cross-disciplinary collaboration and work.  I also didn’t always follow the conventional route most people would advise you to take to achieve something. Never be afraid to take a chance or work with some level of risk.

I also have two or three close mentors that I can approach whenever I require some advice or feedback. No matter what career stage you are at, I think it almost always helps to get an outsider’s perspective and insight not only when there are problems.

Finally, never forget to have fun. Some of my best pieces of work were done when I was surrounded by collaborators that are really fun to be with and work with!

Interview by Olivia Trani, EGU Communications Officer.

References: 

Ilyinskaya, E., et al.: Understanding the environmental impacts of large fissure eruptions: Aerosol and gas emissions from the 2014–2015 Holuhraun eruption (Iceland), Earth and Planetary Science Letters, 472, 309-322, 2017

Schmidt, A., et al.: Satellite detection, long-range transport, and air quality impacts of volcanic sulfur dioxide from the 2014–2015 flood lava eruption at Bárðarbunga (Iceland)Journal of Geophysical Research: Atmospheres12097399757, 2015

Schmidt, et al.: Excess mortality in Europe following a future Laki-style Icelandic eruption, Proceedings of the National Academy of Sciences, 108(38), 15710-15715, 2011

GeoTalk: Hellishly hot period contributed to one of the most catastrophic mass extinctions of Earth’s history

GeoTalk: Hellishly hot period contributed to one of the most catastrophic mass extinctions of Earth’s history

Geotalk is a regular feature highlighting early career researchers and their work. Following the EGU General Assembly, we spoke to Yadong Sun, the winner of a 2017 Arne Richter Award for Outstanding Early Career Scientists, about his work on understanding mass-extinctions. Using a unique combination of sedimentological, palaeontological and geochemical techniques Yadong was able to identify some of the causes of the end-Permian mass extinction, which saw the most catastrophic diversity loss of the Phanerozoic. 

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

Many thanks for inviting me here. I am currently working at the GeoZentrum Nordbayern, University of Erlangen-Nuremberg as a post-doc researcher.

I grew up in a small coastal town called Haiyang, east to the major city Tsingtao in North China. I moved to central China for university and majored in Geology at the China University of Geosciences (Wuhan) in 2004-2008.

This was followed by an exciting, 5 years split-site PhD program in which I spent two and a half years in China for field work and palaeontological training; half a year at Erlangen Germany for stable isotope and geochemical studies and the final 2 years at the University of Leeds, UK for training in sedimentology.

After my PhD, I successfully applied a fellowship from the Alexander von Humboldt Foundation and become an honourable Humboldtian.

In late 2015, two years after my PhD, I had 31 peer-reviewed papers including two in Science but was not fully prepared for the job market. It was already near the end of my fellowship. I only applied for one job—the O.K. Earl postdoc fellowship at the California Institute of Technology, US, but I didn’t get it. Completely unprepared for the situation, I was unemployed for about half a year.

I considered this the first setback in my early career. It taught me a valuable lesson; since I applied various research funding and fellowships and have never failed.

In early 2016, I was offered a postdoc position in a big project from the German Science Foundation (DFG forschergruppe) at Erlangen. I am very happy to be involved in the project and work again with many German and European colleagues.

Meet Yadong, pictured on fieldwork in the Himalayas. Credit: Yadong Sun.

During EGU 2017, you received an Arne Richter Award for Outstanding Early Career Scientists for your work understanding the end-Permian mass extinction. Could you tell us a little bit more about this period during Earth’s history?

The end-Permian mass extinction, which happened 252 million years ago, is the most devastating crisis seen in the Phanerozoic (the period of time during which there has seen life on Earth). However, the ultimate killing (or triggering) mechanism of this mass extinction is not fully understood and has been intensely debated for years.

Many fossil groups, in the ocean and on land were completely wiped out. The end-Permian mass extinction had profound influence on the evolution of life on Earth; such was the scale of the dying at this time. Extinction losses appear non-selective; virtually no groups escaped unscathed.

In the oceans some of the most abundant organisms such as the brachiopods (two-shelled organisms), radiolaria and foraminifera were almost (but not quite) eliminated whilst the rugose corals, tabulate corals, goniatites and trilobites were forever lost.

On land, the dominant herbivorous animals, the pareiasaurs, together with the gorgonopsids, the top predators, were lost. They lived in a world in which the dominant trees were the seed-bearing gymnosperms (e.g. glossopterids, gigantopterids, cordaites). All these groups, together with many other animals, including diverse insect groups, failed to survive the extinction.

After the mass extinction, the Early Triassic world was a time of extraordinary low diversity with the same monotonous communities found everywhere. For example, there is a 5 million year gap during which corals are not found in the rock record.

On land this included assemblages dominated by a shrub-like tree fern called Dicroidium, whilst the dominant animal was Lystrosaurus a pig-sized herbivore, belonging to a group called the dicynodonts.

In the world’s oceans, in the immediate aftermath of the extinction, it was the mollusks which occurred in the greatest numbers; a bivalve called Claraia was prolifically abundant just about everywhere.

It took an unusually long time (around 4-5 million years) for the biosphere to start recovering from the end-Permian mass extinction. This is much longer than after other mass extinctions and has lead scientists to speculate that the harsh conditions, responsible for the extinction in the first place, may have persisted for long afterwards.

At the same time, ocean chemistry was probably very different to modern day Earth. The oxygen levels in seawater were very low.

Despite the debate, what do scientists know about the causes of the end-Permian extinction?

The causes of the end-Permian mass extinction are, as a matter of fact, not perfectly understood. There are many different hypotheses. The key is to test the different hypotheses.

At the moment, we know with quite some certainty that anoxia (no free oxygen in seawater) and high temperatures both likely contributed to the end-Permian mass extinction.

Around the time of the extinction, there was massive volcanic activity in present day Siberia, known as the Siberian Traps. The lavas they left behind are known as the Siberian flood basalts. The eruption of the super volcano triggered global warming, voluminous volcanic CO2 inject to the atmosphere could lead to ocean acidification. This is because CO2 reacts with water and becomes carbonic acid (CO2 + H2O ↔ H2CO3). This is a very new and popular hypothesis to explain the mass extinction.

However, I myself am not fully convinced by the ocean acidification theory for the end-Permian mass extinction because there is a lot of evidence for carbonate over-saturated conditions at this time too. Carbonate saturated conditions mean that seawater contains very high concentrations of species such as CO32- and HCO3. They easily combine with Ca2+ and precipice as limestone and calcite cements. High concentrations CO32- and HCO3 have a buffering effect which inhibit the reaction forming carbonic acid. Therefore, it is not really possible to have ocean acidification and carbonate over-saturation at the same time. More detailed studies are needed to investigate this paradox.

In the past, some scientists proposed a sudden cooling or bolide impact as potential causes for the extinction, but these theories are no longer popular because of a lack of evidence.

In your presentation at EGU 2017 you spoke about how the extinction was accompanied by a rapid temperature rise, from 25 °C to 32 °C. How were you able to establish that such a significant temperature rise occurred?

I use oxygen isotope thermometry from conodonts: an extinct eel-like creature. Oxygen has two isotopes—18O and 16O. The ratio of the two isotopes in an animal is proportional to temperature from the oxygen isotope ratio of the water they ingest.

Reconstruction of temperatures for the end-Permian mass extinction is not easy since most shelly fossils died out. Those preserved are often subject to burial changes and therefore no longer preserve the original environmental information.

On the other hand, conodonts survived the end-Permian mass-extinction and are ideal for oxygen isotope analyses. They are very tiny (typically ~300 micro meter long) and consist of biogenic apatite. Apatite has 4 very robust P-O chemical bonds and very difficult to be altered after burial. Therefore, measuring oxygen isotope ratio of conodonts could help solved the problem.

However, because conodonts are so small and rare in rocks, I had to collect 2 tons of carbonate rocks dissolve the rock in acetic acid and pick the conodonts one by one under a binocular microscope, to get a big enough sample! It was a lot of work and required a lot of patience.

A Triassic conodont from south China. Credit: Yadong Sun.

That certainly sounds like painstaking work! Once the tedious task was completed, how were you able to link the temperature records you deciphered from the conodonts with the mass extinction?

All living creatures have a thermal threshold, also called thermal tolerance – the temperature range which they are able to tolerate to survive. It varies significantly amongst different groups. Most animals, on land or in the oceans, cannot live in environments that are consistently hotter than 47 °C. However, certain groups of desert ants and scorpions have developed special mechanisms and can survive 53 °C for a very brief time. Another example is the elevated seawater temperatures which contribute to high death rates of corals.

High temperatures supress photosynthesis. In most C3 plants, at temperatures above 35°C, photorespiration exceeds photosynthesis, wasting the energy generated by the plants.  in most C3 plants. Under such circumstances, C3 plants will stop growing and probably die shortly after. Maximum growth rates of single-celled algae in the ocean are normally achieved below 40°C.

A significant rise in seawater temperatures has many negative effects. One of them is that the amount of oxygen dissolved in seawater decreases as temperature rises, while animals use up more energy to perform even the simplest tasks. . This is one reason for which most marine groups prefer environments < 35°C.

These observations tie mass extinctions with temperature increase.

For our study, once the oxygen isotope ratios of conodonts are measured, we can use it in an equation to calculate the absolute temperature of the seawater at the time. The results show significantly higher ocean temperatures than today. We know the equation explains the relationship accurately because it was established in aquariums where scientists raise fishes in controlled temperatures. As temperatures are known, they measure the oxygen isotope of the water and fish teeth and established the oxygen isotope—temperature equation.

What do your findings mean for the current understanding of the causes of the mass-extinction?

This is an excellent question. There are quite some studies which postulate global warming as a potential killing mechanism for the end-Permian mass extinction. There is a link between the timing of the massive eruptions of the Siberia Large Igneous Province and the end-Permian mass extinction, which has led scientists to propose different warming scenarios. They are all correct, but they are not able to show direct evidence for their hypotheses or quantify the temperature change.

Our data show the worst-case scenario in terms of temperature rise and the mass mortality of species. This does not necessarily imply high temperatures killed everything because many adverse environmental conditions could trigger synergetic effects (for example low oxygen levels). Our study set an example for comparison.

Our results mean that rapid warming, such as what we are encountering at present, is truly worrying.

Yadong, thank you for speaking to me about your reasearch. As an award winner with an impressive career so far, what advice do you have for early career scientists?

Europe is probably the best place in the world for young scientists. It provides considerable fair funding opportunities and many possibilities to work with other scientists in the EU.

However, it is undeniable that fixed positions in academia are rare and highly competitive. It is always the best to go to meetings/conferences at least once a year to showcase your research, meet colleagues and seek collaboration opportunities.

Research projects nowadays are much more complex. Many tasks cannot be done by one person or one team. The success of a young scientist cannot be achieved without the support of senior scientists as well as the community.

Also don’t be shy to contact people and always be prepared for the job market. In the post-doc stage, if your project is very challenging, the best strategy is to work on some small projects on the side and keep publishing.

Interview by Laura Roberts Artal (EGU Communications Officer)

References

Sun, Y. Climate warming during and in the aftermath of the End-Permian mass extinction, Geophysical Research Abstracts, Vol. 19, EGU2017-2304, 2017, EGU General Assembly, 2017