GeoLog

“Rain is grace; rain is the sky descending to the earth; without rain, there would be no life.” – John Updike

Rain quenches the thirst of soils and vegetation, fuelling ecosystems and much of the world’s agriculture. Whether it ruins a day on the beach or destroys a season’s harvest, it makes humans deeply aware of their vulnerability to the vagaries of the atmosphere. It’s important to understand how rainfall changes in a changing climate. Here, I will describe the issues in understanding precipitation changes and how two recent papers help to solve the puzzle.

Predicting rainfall is difficult. It is a small-scale phenomenon, especially in the towers of convective cloud in the Tropics. Weather forecasting models are just beginning to capture them properly at scales of a kilometre or so, but climate models, which have to be run for decades rather than days, calculate atmospheric conditions on scales of hundreds of kilometres. Rainfall has to be simplified in these models, since we cannot calculate the physical properties of individual clouds. These simplified representations are called parameterisations. A precipitation parameterisation relates the average rainfall over a large area to the average amount of water in the air. Different models do this in different ways and, because it’s a simplification, there is no definitive ‘right’ way. This means there is some disagreement among climate models about how rainfall will change in the future, especially in the Tropics (areas on the figure which are not stippled).

Climate model projections of precipitation change in a future with high greenhouse gas emissions. Left: current generation of models, Right: previous generation of models (around 2005). Top: December-February, Bottom: June-August. Stippling shows areas where models largely agree. White areas show complete disagreement among models (source: Knutti & Sedlacek, 2013).

If we think about precipitation in general theoretical terms, we can find laws which must be followed and use them to make predictions, as Issac Held & Brian Soden did in their study of how the hydrological cycle responds to global warming. Rain is caused by the upward transport of water vapour from the surface into the atmosphere, where it condenses, forms clouds and rains out. The amount of moisture going up must, of course, balance the amount coming back down as rain.

As the climate warms, the amount of water vapour a fixed mass of air can hold increases. This means that, as long as the circulations transporting water upwards remain the same, the total amount of water vapour going upwards must increase – which means the amount of rain coming down must also increase. This is called the ‘rich get richer’ mechanism, because it increases rainfall in regions where there is already a lot of rain driven by upward moisture transport. It’s a fundamental mechanism driven by thermodynamic laws…but that doesn’t mean it’s the only thing going on.

Convective raincloud in tropical Africa (photo credit: Jeff Attaway).

If climate model projections followed the ‘rich get richer’ mechanism, precipitation would increase most in the regions with the most precipitation currently. In fact it is more complicated than that. Robin Chadwick and his colleagues explored the effect of weaker vertical motions in a warmer climate. We can understand this by thinking about what carbon dioxide does to the vertical temperature profile. It warms the mid-troposphere (about 5 km up) more than the surface. To get convective upward motion, the air at the surface must be less dense (i.e. warmer) than the air above. Warming the air aloft suppresses this motion. The Chadwick decomposition calculates the part of the precipitation changes caused by changes in moisture (which goes at about 7% per K) and the part caused by the reduction in upward transport. They find the two tend to roughly cancel each other out, which means the spatial shifts in precipitation are determined by changing patterns of surface temperature (since warm surfaces produce upward motion).

Sandrine Bony and her team decompose precipitation changes into two main components rather than three: one is the ‘dynamical’ component, associated with changing upward motions, and the other is the ‘thermodynamical’ component, including changes in atmospheric moisture content. Unlike the Chadwick method, the thermodynamical component is not designed solely to represent the ‘rich get richer’ mechanism. This means the thermodynamical component isn’t just a 7% per K increase; it includes things like the spatial changes in surface temperature. The dynamical component isolates the change in precipitation caused by changes in upward motion.

Monsoon raincloud over a lake in the Tibetan Plateau (photo credit: Janneke Ijmker).

The ‘rich get richer’ rule of thumb becomes increasingly irrelevant at smaller scales. This is frustrating, because these are the scales we really care about! It’s not particularly useful knowing what will happen in a general sense over the whole Tropical region. Farmers want to know what will happen to the seasonal rains on their small piece of land.

Bony also points out that geoengineering schemes which aim to reduce incoming solar radiation to cool the planet’s surface would leave the dynamical component of precipitation change untouched. This is because the dynamical component is caused by the warming of the mid-troposphere by carbon dioxide, and this remains even if we cool the surface. It is an example of the inexact nature of the cancellation between carbon dioxide increases and geoengineering schemes to decrease the amount of carbon dioxide in the atmosphere, and demonstrates that the only way to stop carbon dioxide-driven climate change properly is to stop emitting carbon dioxide.

Bony and Chadwick’s decompositions show how one can glean a lot more information from climate model projections than one would expect from first glance. We have established some general facts about climate change related to the Earth’s energy budget. In that sense we understand quite well what will happen in a warming climate. However, there is still a lot of diversity between model projections, most of which comes from differences in the dynamical response. Local changes in rainfall are related to changes in circulation, and this is the area in which a lot more work needs to be done.

By Angus Ferraro, PhD student at Reading University

References:

Bony, Sandrine, Gilles Bellon, Daniel Klocke, Steven Sherwood, Solange Fermepin & Sébastien Denvil, 2013: Robust direct effect of carbon dioxide on tropical circulation and regional precipitation, Nat. Geosci., doi:10.1038/ngeo1799

Chadwick, Robin, Ian Boutle & Gill Martin, 2013: Spatial Patterns of Precipitation Change in CMIP5: Why the Rich don’t get Richer in the Tropics. J. Climate, doi: 10.1175/JCLI-D-12-00543.1

Held, Isaac M., Brian J. Soden, 2006: Robust Responses of the Hydrological Cycle to Global Warming. J. Climate, 19, 5686–5699. doi: 10.1175/JCLI3990.1

Knutti, Reto & Jan Sedláček, 2013: Robustness and uncertainties in the new CMIP5 climate model projections, Nat. Clim. Change, doi: 10.1038/nclimate1716

Following their talk at EGU 2013, Helen Goulding and Sarah Blackford have put together their top tips for finding a job, whether you’re looking to stay in science or use your skills elsewhere. Sarah shares her secrets in the second post in this short series…

“Congratulations! You have been invited for interview.” These are the words everyone wants to see following the submission of a job application. But the initial flush of pleasure and excitement can soon give way to feelings of trepidation and apprehension. So how can you reduce your anxiety and ensure you give yourself the best possible chance of succeeding at interview? The 7 ‘Ps’ can help to put you on the right career track:

Purpose – Keep in mind the purpose of an interview, which is for the employer to find out more about you and vice versa. Meeting you in person will allow him/her to see how well you communicate and whether you will fit into the team/organisation.

Plan – Review the job description, company/research group and personal requirements. Find out the details of the interview location and set-up. This should have been specified in your interview letter but, if not, contact the organisation to ask how long the interview will be and who will be on the interview panel. If there is a presentation, who will be in the audience? This will help you to make the content of your answers and/or presentation relevant.

Prepare – You are bound to be asked to clarify or expand on much of the content of your application/CV so make sure you can give examples relevant to the employer and bring the content to life. Think of one or two brief questions to ask the interviewer (but don’t ask about salary until you’ve been offered the job!).

Predict – As with an exam you can probably predict many of the questions you are likely to be asked. Put yourself in the shoes of the employer and imagine what you would want to know from the applicant. As well as detailed technical questions (depending on the job), they are likely to ask you open-ended questions. For example:

• Why do you want this job?
• What can you bring to the organisation?
• Tell me about any challenges you encountered during your PhD/research? How did you deal with them? What was the outcome?
• If you had a grant of €5million, what would you want to spend it on? (In other words, what big ideas do you have in your mind in terms of this research area).

Practice – Try to set up a mock interview or just practice saying some of your predicted answers out loud to yourself. This will help you to familiarise yourself with your evidence and identify any gaps or weak areas in your performance which you can work on a bit more.

Perform - Good body language and eye contact is essential to make a good impression. Dress to impress (at the same level of formality as the interview panel) and don’t forget that how you say what you say – the tone and assuredness of your voice – is as important as what you say.

Persist – Using these ‘rules’ you should be able to optimise your chances for a successful outcome to your interview. However, if you are turned down don’t take it personally. Ask for feedback, review your performance, move on and persist with your applications – imagine and believe in your ultimate success!

By Sarah Blackford

Sarah Blackford is a qualified careers consultant and author of ‘Career planning for research bioscientists’. For more information on interview technique see:
http://www.biosciencecareers.org/2013/04/interviews-when-coming-2nd-is-no.html

Whether you’re climbing, hiking or caving, it’s hard to ignore the geology around you. For keen climber and environmental geoscientist Ivan Bour, a trip to the French Alps is no exception…

I’ve practiced mountain climbing for a dozen years. During my ascents, I seek geomorphological and geological peculiarities. Very often, I associate my profession as a geologist with my activities in the high mountains that allow me to capture new images of the Alpine peaks. This one captures the glacial curiosities of the southern French Alps.

“Syncline ice” by Ivan Bour, showing the deformation in synclinal structure of ice layers (Arsine glacier, 2500 m, Ecrins massif, Alps, France). This photo is distributed by the EGU under a Creative Commons licence.

The picture was taken on the Arsine glacier within the French Alps (northeastern edge of Ecrins massif, Ecrins National Park). This glacier begins on the slopes of a circus with a horseshoe form open northbound (which corresponds to a glacier circus). The glacier is dominated by a high wall of crystalline rocks oscillating between 3200 and 3600 meters over Agneaux peak, the Neige Cordier peak and Arsine peak. This wall is deeply lacerated by countless avalanche corridors that supply the glacier with packed snow and rock debris.

The amount of accumulating ice and the maintenance of the ice volume is related to the shelter phenomenon caused by the mountain barrier, which compensates for the relatively low average altitude of the glacial system (2731 m). The Arsine glacier is between 2450 and 3600 meters above sea level and is 1.7 km long. The glacier front takes the particular form of an ice cliff that plunges into a lake, fed by meltwater from the glacier. These waters are retained by the frontal and lateral moraines. The altitude of the glacier is very low in the circus, the erosion of the mountain barrier produced a steady dusting of heterogeneous rocks and these gneiss and granite blocks cover the surface of the ice. Its debris shell (approximately 5 to 10 m thick) preserves the glacier to climatic contrasts (summer seasons). In France, this type of glacier is called a black glacier.

This picture shows a close-up of the serac front (formed when crevasses on a glacier meet) observed from the medial moraine. The gray waves of the ice cliff are small rocky debris deposits, which are interspersed between ice layers. The layers show periods of ice formation (winter-spring) alternating with periods of debris accumulation (summer-autumn). The moraine surface is a carpet of rocks that obscures the surface of the glacier. Modern ice shows a beautiful syncline of successive layers whose axis is the centre of channel flow. The syncline you see here is a consequence of the ice flow, as the glacier adapts to the shape of the flow circus (depression of the centre and compression of the sides). The ice layers are accumulated in a wide V, and then compressed during the flow downstream. The serac front is continually evolving and undergoes flaking processes that quickly change the morphology of the glacier in the downstream zone. The increasing average temperatures experienced in this regoin are accelerating this process.

By Ivan Bour, Université de Bourgogne

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licensed and distributed by EGU under a Creative Commons licence.

Do you use Imaggeo? Help us improve the website by letting us know what you’d like to see changed using this short questionnaire!

Finding a job can be a daunting task, whether you’re looking to stay in science or use your skills elsewhere. Helen Goulding and Sarah Blackford have put together a short series on how to make a great application and excel in an interview, sharing top tips from their talk at EGU 2013. Here are Helen’s highlights…    

Imagine for a moment that you are an employer and that you need to fill a vacancy. You carefully craft an advertisement and send it out to the world. You wait impatiently for the responses to come in. The deadline arrives and you are happy to see a large folder of applications.

You open the first application and scan it for 20-30 seconds. It is densely written, in tiny font and mentions none of the key skills from the advert. Not a good start. You pick up the second application and read a vague description of the applicant’s research interests and one limply enthusiastic sentence about working with you. You sigh and add it to the “No” pile. You pick up the third application and discover that the candidate likes reading, basketball and is PADI qualified. You are unsure how this relates to your vacancy or what he has been doing since he finished his PhD. You sigh; this is going to be a long day…

As an applicant there are simple but effective things you can do to increase the chance of your application / CV going into the “Yes” pile. Here are some brief tips:

1. Make your application easy to read. Most recruiters will spend less than one minute reading it initially. So use a minimum font size of 11 and use subheadings, bullet points, white space and bold font to increase readability. Spell- and grammar check your applications carefully.
2. Make your text match the skills and experience requested in the advert and make sure you provide all the information they ask for. Yes, this does mean you should be writing a different CV / application for every single job you apply for!
3. For an academic job, highlight your research experience, projects delivered, publication record, funding gained and experience of collaboration, teaching and staff management.
4. For an industry job, unless it is a technical science job, take all the science jargon out of your CV. Include your science degree and PhD but never list modules taken or thesis titles – these are irrelevant and off-putting to the non-technical recruiter.
5. If you don’t have much relevant work experience, create a section on skills, with headings to match the skills requested in the advert. Under each heading give a couple of bullet point examples of that skill, saying what you did and the outcome.
6. Edit your draft application brutally and remove all unnecessary information. To maximise the space available for relevant information: a) Use bullet points  b) Put all your contact details on one line c) Delete information on your hobbies, it is irrelevant  d) Write “References available on request” rather than listing full contact details.

Following these steps carefully should significantly increase your chances of being called for interview. Good luck with your job search!

By Helen Goulding

Helen Goulding is Director of Quercus Training, a company that trains scientists and engineers in transferable skills.

Geotalk is a regular feature highlighting early career researchers and their work. Today we’re talking to Encarnación Ruiz-Agudo whose specialty lies in crystal growth and dissolution – the key to how rocks tell their stories!

First, could you introduce yourself and let us know a bit about your current research? Also, what sparked your interest in crystallography and mineralogy?

My name is Encarnación Ruiz-Agudo, and I am currently working in the Department of Mineralogy and Petrology of the University of Granada (Granada, Spain), as research fellow. During my career, I have performed active research in a number of topics. My PhD research, under the supervision of Prof. Carlos Manuel Rodríguez Navarro, was aimed at gaining a better understanding of the effects of organic compounds on the crystallisation of soluble salts such as sodium and magnesium sulphate, and on sodium nitrate as a possible means of protecting ornamental stone against salt damage. With this in mind, I studied the physical and chemical processes causing the damage to calcitic stone materials, and how some organic compounds can modify such processes. I also investigated other mechanisms of damage to the built cultural heritage, such as gypsum crust formation, and conservation strategies that can be employed to protect them, such as the use and design of conservation lime-based mortars.

Encarnación Ruiz-Agudo herself!

My postdoctoral research began when I joined the research group of Prof. Andrew Putnis(Institute für Mineralogie, University of Münster, Germany). I was awarded a two-year Marie Curie contract in this group within the European Initial Training Network, DELTAMIN. There, I conducted studies in situ – and at the nanoscale – using Atomic Force Microscopy (AFM) to investigate the chemical mechanisms that cause salt damage, specifically the processes of carbonate dissolution in the presence of electrolytes and organic compounds i. During my time there, I gained expertise in geochemical modelling as well as in the use of in situ AFM to obtain kinetic and mechanistic information on mineral growth and dissolution processes. My main focus: the nanoscale processes during the initial stages of mineral replacement and how epitaxy (structural matching at the molecular scale) between parent and product phases controls the coupling between dissolution and precipitation.

Earlier this year, your received an EGU Arne Richter Award for Outstanding Young Scientists for your “ground-breaking work on the structure of mineral surfaces, on fluid-mineral interaction and on the influence of organic and inorganic additives on the growth of crystals in multicomponent aqueous solutions”. Could you summarise in simple terms the research you have done in this area?

I studied the growth and dissolution of carbonates and silicates, and the effect of electrolytes and organic compounds on these processes. These studies have been performed mostly in situ and at the nanoscale using Atomic Force Microscopy and have opened the possibility of a new understanding of very diverse phenomena in geochemistry. and demonstrates the need for the inclusion of the effects of “foreign” molecules on the ions building the mineral when developing predictive models that describe crystal growth and dissolution in complex systems, such as those we find in nature.

The results of my research have provided evidence that supports a dissolution-precipitation mechanism for the formation of altered layers on the surfaces of minerals. This is critical as these altered layers may have a significant effect on the reactivity of these minerals and likely glasses, and help explain the apparent discrepancy – in orders of magnitude – between field and laboratory dissolution rates.

An atomic force microscopy (AFM) picture of a growth spiral, which developed on a calcite (CaCO3) surface during growth – pretty cool eh?

What is the wider importance of your research work?

My results so far are inapplicable to a wide range of fields including: cultural heritage conservation, biomineralisation, medicine, CO₂ sequestration and the oil and cement industry, where mineral-electrolyte interactions and replacement reactions are of paramount importance. The research performed in some of the topics described above has given rise to the patent “Binder for CO₂ sequestration: A manufacture method by selection, purification and optimization of carbide lime, and binders of environmental activity”, of which I am one of the inventors. This demonstrates the practical applications of my accomplishments, particularly since it is actually being exploited by a Spanish company!

As this interview is being conducted, you are on maternity leave. What advice would you have for young female scientists wondering how to balance their research work with starting a family?

I think it is a really tough work and I am still learning how to do it so I cannot give much advice on that. I believe that having support from your partner and from your work environment is critical. I think that women with a family and a research career must be prepared to work hard almost 24 hours a day, but I think it is doable if you like your job!

Last but not the least, what are your future research plans?

In the future, I would like to continue performing active research in this field at the University of Granada. I would also like to start a new research line relating to the mechanisms of element incorporation into minerals from aqueous solutions, with the aim of gaining a better understanding of environmental proxies. Our ability to understand how past climate evolves with time, and thus to predict future climate change, depends on being able to comprehend mechanisms and responses of the mineral, with respect to ion incorporation and changes in its growth environment. Furthermore, the same understanding is needed to control processes of importance to industry and society in general, such as the removal of toxic metals from polluted environments. The broad applicability of this research to urgent environmental and technological problems makes it of direct relevance to both public and private sectors.

If you’d like to suggest a scientist for an interview, please contact Sara Mynott.

This week’s Imaggeo on Mondays is brought to you by the photographer herself, Jana Eichel, who tells us about her expedition to the Mingsha Mountains and the stunning aeolian landforms that characterise the landscape.

“Star dune in the Gobi desert, Dunhuang, China” by Jana Eichel, distributed by the the EGU under a Creative Commons licence.

This photo was taken during a journey through Asia in spring 2012, which took me across Bangladesh, India and Nepal through to Western China and into the Gobi Desert. This journey allowed me to appreciate the enormous variety of landscapes in Asia as well as  the different cultures. To experience ‘the desert’, which has fascinated me for quite a while, I joined  four others on an (ever so slightly touristy) overnight camel trek to the borders of the Mingsha Mountains, where this photo was taken. This megadune field is located south of Dunhuang (Gansu province, China) in the Gobi Desert. The dunes, which are aeolian depositional landforms, are between 60 and 170 m heigh and are formed mostly by westerly and southerly winds. In the neighborhood of this dunefield, the World Cultural Heritage of the Mogao Caves is located, which house a large collection of Buddhist art. There is a fear that they will be overrun by the Mingsha Mountains (megadunes) in the future, which are slowly advancing in this direction.

The Gobi Desert (source).

The image was taken from near the top of one of the large pyramid dunes at the northeastern border of the dunefield. From here you can see the foothills of the Mingsha Mountains with various dune types, which are determined by a multitude of influencing factors, including wind direction variability and sand supply. Our camp in the lower left of the picture puts these huge landforms into perspective.

Most prominently in the foreground next to the camp is a star-shaped dune. These dunes are generally formed by multidirectional winds when there is a large sand supply. These conditionscreate a set of slip faces that project out in  multiple directions, such that the dune represents a star – hence the name! Transverse dunes and barchanoid ridges can be seen in the background, where they phase out towards the plains, likely dues to a decreasing sand supply. Dunefields such as this, with a variety of dune types highlight the complexity of geomorphic systems, Aeolian systems, such as the one here are thought to be strongly driven by self-organisation. This means the complex non-linear dynamics of the system do not result in chaos but instead in order: the smallest elements in the system, such as the sand grains, assemble into larger scale objects, such as the dune patterns shown (Dikau, 2006). This emergent behaviour cannot be predicted even if all processes fundamental for the evolution of these dunes are known.

To account for the impressive landscape with its large-scale geomorphic forms, I used a high aperture to give the picture a greater depth. This was amplified by the sunset light, which  created long shadows behind the dunes and gave a better impression of the contours of the dunes, which are partly obscured during the day.

By Jana Eichel, University of Bonn  

References:

Dikau, R. (2006): Complex systems in geomorphology. Mitteilungen der Österreichischen Geographischen Gesellschaft 148, 125-150.

Jianjun, Q., Ning, H., Guangrong, D. and Weimin, Z. (2001): The role and significance of the Gobi Desert pavement in controlling sand movement on the cliff top near the Dunhuang Magao Grottoes. Journal of Arid Environments 48, 3, 357-371.

Kocurek, G. and R.C. Ewing (2005): Aeolian dune field self-organization – implications for the formation of simple versus complex dune-field patterns. Geomorphology 72, 94-105.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licensed and distributed by EGU under a Creative Commons licence.

The absorption of atmospheric CO₂ by the oceans results in a decline in ocean pH, hence ‘ocean acidification’, and reduces carbonate ion availability. This presents a problem to calcifying organisms (those that deposit calcium as either calcite or aragonite as hard parts) because they cannot produce their shells, valves (in the case of bivalves), or tests (in the case of diatoms) as readily.

To explain this, we need a little chemistry. When CO₂ dissolves, it combines with water to form carbonic acid (H₂CO₃). This then breaks down to form bicarbonate (HCO₃^-) when one hydrogen ion is lost, and then carbonate (CO₃^2-) as the other hydrogen ion is lost. This carbonate is the important stuff, as it combines with calcium to form the calcium carbonate (CaCO₃) used by bivalves to produce shells. If something (such as the ocean) is more acidic, there must be more hydrogen ions available. These hydrogen ions interfere with the calcification process as they bond with carbonate, meaning there is less available for shell formation.

Calcification: carbonate chemistry in action!

This process is relatively well established for a number of calcifying organisms, although there are exceptions to (the coccolith, Emiliania huxleyi, for example) and the response to elevated CO₂ levels is not uniform across species.

Much of current research has focussed on the effect of constant CO₂ levels on calcification, but what about animals that live in environments where the CO₂ concentration is constantly changing? The availability of carbonate in estuaries is particularly variable as CO₂ concentrations vary seasonally (there’s a greater carbon load in the winter as storms wash nutrients into rivers), diurnally and with the tide. The impact of elevated CO₂ levels on an organism is also dependant on its life stage; something that is particularly true of bivalves.

Bivalve larvae. Photo credit: Minami Himemiya (source).

Bivalves spend the first part of their life in the plankton, first as a veliger (a relatively amorphous looking ciliated blob) and then as a pediveliger (that same blob, but this time with an identifiable foot) before metamorphosing into a miniature adult. During these larval stages, they are particularly vulnerable to ocean acidification and, until recently, both the reasons behind this, and the longer-term implications of this vulnerability, were unclear.

This is where doctors Christopher Gobler and Stephanie Talmage come in. They took to the lab to tackle why larvae are especially vulnerable to acidification and what this means for them in both the short and long term. It’s impossible to take a look at how all bivalves respond to acidification, though, so to tackle these questions, two bivalve species, the hard-shelled clam (Mercenaria mercenaria) and the Atlantic bay scallop (Argopecten irradians) joined the team.

The Atlantic bay scallop, Argopecten irradians. Photo credit: Rachael Norris and Marina Freudzon (source).

Using their RNA:DNA ratio as a proxy for growth and the uptake of a radioactive calcium isotope, ⁴⁵Ca, to estimate calcification, Gobler and Talmage found that growth in the presence of elevated CO₂ results in individuals of a smaller size. This is because there is less calcium available for uptake. Their findings, revealed that high CO₂ concentrations, not only affected size, but also negatively impacted bivalve physiology, as individuals reared in these conditions were found to have thinner shells. Shells are an important defence against predators and the reduction in shell thickness (and hence strength) may put them at greater risk from predation.

The higher the CO2, the slower the calcium uptake: calcium uptake rates of larval Atlantic bay scallop, Argopecten irradians, under different CO2 concentrations over a 12-hour period (Gobler and Talmage, 2013).

When transferred from a high CO₂ environment to an environment with an ambient CO₂ concentration, larvae grew faster than those in ambient conditions throughout the whole of their development. However, this higher growth rate doesn’t compensate for the low calcification rate during larval stages, as their final is still smaller than individuals reared in ambient conditions at all life stages. This “legacy effect” presents a significant problem for adult bivalves, due to the detrimental impact of reduced calcification on their defences.

By Sara Mynott, EGU Communications Officer

Reference:

Gobler, C. J. and Talmage, S. C.: Short- and long-term consequences of larval stage exposure to constantly and ephemerally elevated carbon dioxide for marine bivalve populations, Biogeosciences, 10, 2241-2253, doi:10.5194/bg-10-2241-2013, 2013.

This week’s Imaggeo on Mondays is brought to you by the photographer himself, Fabien Darrouzet who captured the beautiful glacial landscape during a summer expedition to the Arctic. 

“Arctic through a porthole” by Fabien Darrouzet, distributed by the EGU under a Creative Commons Licence.

This picture was taken in Svalbard (78° lat.) in June 2012. I was there for one week in order to observe the transit of the planet Venus in front of the Sun. I came here because at this time of the year, the Sun is shining all day (midnight Sun), so it was possible to see Venus during most of the transit (for over six and a half hours!), and not only during its last minutes, as was the case for most parts of Europe.

During the days before the transit, I made a boat trip inside the fjords around Longyearbyen, and in particular in the Isfjorden, where I took this picture through the porthole of the boat. This is the southern border of a territory of Svalbard named Oscar II Land. This area, and indeed all of Svalbard, is covered by snow most of the time, and just a few plants can germinate during July-August, when the average temperature is 5°C.

Svalbard is a very important island and region because it is dominated  by glaciers (60% of all the surface), which are important indicators of global warming and can reveal possible answers as to what the climate was like up to several hundred thousand years ago. Those glaciers are studied and analysed by scientists in order to better observe and understand the consequences of the global warming on our Earth.

By Fabien Darrouzet, Belgian Institute for Space Aeronomy

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licensed and distributed by EGU under a Creative Commons licence.

This month in Geotalk, we spoke to Robin Andrews, a PhD candidate at the University of Otago, New Zealand, who takes us through the explosive aspects of one of Geology’s most thrilling disciplines – volcanology.

First, could you introduce yourself and let us know a little about your work and what drew you to volcanology?

Ah, introductions! Well, I’m Robin Andrews, a British postgraduate volcanology student currently based in New Zealand. I’m listed as an experimental volcanologist – apparently with an emphasis on the mental, according to some colleagues of mine. When I’m normally asked how I got into volcanology, I give a similar answer to the question of why I got into science in the first place. As a child, I often conducted scientific experiments in my home without the permission of my parents: melting all of the cutlery in the kitchen drawer using a lot of batteries was a highlight. The moment I found out that we are all the bottled, biological results of the accumulation of stardust, billions of years old, I knew I wanted to study something that painted such an epic picture in everyone’s minds in an instant. Volcanoes fit the brief nicely: no inner child can watch them erupt and not be bowled over in awe.

Nowadays, I absolutely love studying volcanic systems that could be works of natural art. My dream is to head to Iceland and use a snowmobile to circle around the eruption column of one of their very active volcanoes. At the time of writing, I spend most of my academic time setting off controlled explosions – both large and small – and study the dynamics of them through a variety of instrumentation; I use this data to make comparisons to explosive volcanic systems that would otherwise kill me if I stood by and observed them in person.

Robin Andrews. “Equipped with his five senses, man explores the universe around him and calls the adventure Science.” – Edwin Hubble.

My PhD is very satisfyingly unorthodox. I’m studying maar-diatreme volcanic systems, which are a poorly understood and badly defined type of volcanic system. Unlike most volcanic eruptions, which involve continuous eruptions, these systems are blasted into existence by one or multiple discontinuous blasts. As a consequence of this, there are many comparisons made to military and nuclear explosions, so, rather excitingly, for my PhD, I get to blow up a lot of things, from small gas blasts in a laboratory in Germany to large-scale TNT detonations in a field somewhere in the United States, all filmed on extremely high-speed cameras. These experiments have actually revealed a physical mechanism in explosive volcanology – and in crater-forming military explosions – that has not be seen before, thanks to the equipment used, a little bit of physics, and a tiny sprinkling of mathematics, it has been quantified for the first time, and a few journal papers I’m writing now hope to compare these results to both field geology examples and military tests. A recent collaboration with some rather brilliant scientists in the United States has also started the wheels turning on a project involving the volcanism of Io, which aims to investigate whether the aforementioned physical phenomenon could apply to the innermost Galilean moon of Jupiter.

Your PhD is focused on the dynamics of the 1886 Rotomahana eruption – what do we know already and how does your work feed into this?

We know that the eruption was rather unusual, in that the eruption ejecta produced by the roughly synchronous reactions of both the subaqueous magmatic system – which formed numerous gigantic depression craters – and the large stratovolcano nearby were pretty much indistinguishable. Apart from that, the actual mechanism for the eruption of the underwater sections, both thermally and mechanically, are almost entirely hypothetical. We know from very recent experiments that just adding magma to cold water does not result in any sort of Molten Fuel Coolant Interaction-type explosive release of energy: in fact, almost a third of the energy is released as infrasound. I’m currently focused on the mechanics of the eruption rather than the (far more expensive) thermal system potentially operating in such systems, but I’m hoping to move onto the latter soon. My work was initially focused on just this eruption, but its scope has since expanded dramatically as a consequence of the success of the analogue experiments I have been conducting.

Studying volcanoes can be a risky business – when you’re in the field – how can we use laboratory analogues to better understand them?

Half the fun of studying volcanoes is in the risk! Anything that resembles a scene from an Indiana Jones film or an episode of Doctor Who is fine with me. Nevertheless, it is true that volcanoes are particularly dangerous, and many times, tragically so. As aforementioned, they tend to erupt spectacularly and suddenly just once, often forming as a result of at least one discrete blast. Standing too close to these potential eruption sites – which in this case are incredibly difficult to identify pre-eruption – is almost always a fatal decision. The analogue experiments are a far safer way of testing out theories, especially for maar-diatreme systems. One major benefit of my experiments, for example, is being able to see the manufactured eruptions in “cross-section”; this is not exactly possible to view during actual eruptions.

Magnificent exhumed volcanic structures of the Hopi Buttes volcanic field in Arizona. Credit: Robin Andrews.

But you’re not in the lab all the time – when you’re out, what do you do to share your science with others not in your field?

The great thing is that I’m rarely in the lab, which is partly the fun of studying volcanology: it’s a very outdoors-based, physically active science. As for sharing my science with other people not in my field, this can be broken down into two categories: other scientists, and non-scientists. Volcanology recently came second in a survey of British schoolchildren when they were asked what their ideal career would be – something no doubt (and thankfully) provoked by the (at the time) eruption of that most unpronounceable Icelandic volcano. It’s quite the visually exhilarating science, and it proves fairly easy to convince both other scientists and the general public that it’s a good science to peruse, or to regale others with both academic and anecdotal stories. In the long term, I’d love to communicate science to the masses, but for now, I’m keen on spreading the word to the general public through storytelling. As for other scientists, this year I’m going to several conferences to present the ever-so-slightly cool footage of my experiments – and my findings – and spread the word through academic portals and publishing. The hope is that when I become an established (and hopefully respected!) scientist with a flair for the theatrical, the science communication to the general public will follow. I want to become a good academic first though.

Do you have any advice for budding volcanologists?

Absolutely, and I will phrase it in the following way. I had a conversation with someone wherein the topic of bottled lightning came up. Was it possible to capture volcanic lightning, a strange, striking phenomenon, in a bottle? Of course, the answer right now is no, but consider this: what else is a photographic print if not the bottled, frozen result of a camera capturing and storing light? Scientists set fire to the world in an unstoppable conflagration of knowledge and understanding that simply cannot be matched, with the message underscoring each new discovery being one of perpetual inquiry: the more we know, the more we don’t know, a combination of the laws of nature and human ingenuity. Scientists challenge the definition of the word “impossible”, and volcanologists are a small, but visually resplendent and indubitably exciting part of that. If you enjoy taking risks, seeing otherworldly sights, and travelling to the most beautiful parts of the planet, then get stuck into your physics, chemistry, and geology, and most importantly of all, never stop asking questions. Remain perpetually curious, and be impatient.

So, what next?

Well, it’s a busy year for me: I’ve got a lot of science to get accepted into the literature, a thesis to write, more of the world to see, a good few conferences to go to, and a lot of photography and writing to publish alongside all this wonderful madness. Constantly putting one foot in front of the other, academically and literally.

Peering through a dragon’s spine-style volcanic dyke into the exhumed volcanic field ahead. Credit: Robin Andrews.

If you’d like to suggest a scientist for an interview, please contact Sara Mynott.

Étretat is a coastal region in northern France, well known for its stunning geological landscape. Particularly the headland you see here.

“The chalk cliffs of Étretat” by Chiara Arrighi, distributed by the EGU under a Creative Commons licence.

Headland erosion is perhaps one of the best known processes in coastal erosion, where a crack in the headland is opened and enlarged by hydraulic abrasion. Continued wave action causes the widened crack or cave to break through the headland and form an arch. As erosion continues, the arch collapses, leaving behind a stack (or needle) that erodes down to its base to form a much smaller stump. There are some great examples of other coastal processes describes in The British Geographer.

How headlands form and coastal arches erode. Source: Sbsgeog’s Weblog.

But that’s not all there is to Étretat, the chalky cliffs are composed of several layers, clearly distinguishable in Arrighi’s photo. These chalk layers are of varying hardness and can be clustered into three main strata: the lowest is a light, fine, stratified chalk aggregate, rich in foraminifera; the middle stratum is a compact chalk layer with beds that are tens of metres thick, and the uppermost stratum is composed of chalk nodules that, like the lowest stratum, is rich in foraminifera.

These strata provide insight into how the chalk of the region was laid down: the fine strata would have been a calcareous ooze, deposited by gentle currents and the nodular material would have formed as small “bullets”, before accumulating more calcareous material as they are transported and redeposited elsewhere. The sediments that now make up the Étretat chalk sequences were subject to several episodes of deformation and slumping before cementing to form the layered cliffs you see above.

References:

Dercourt, J. and Paquet J. (1985). Sedimentary Facies. Geology Principles and Methods, pp. 195-206.

Bromley, R.G. and Ekdale A.A. (2006) Mass transport in European Cretaceous chalk; fabric criteria for its recognition. Vol. 34, pp.1079-1092.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licensed and distributed by EGU under a Creative Commons licence.