Interview: Plants and their fungi to slow down climate change

César Terrer, participant in the IIASA 2016 Young Scientists Summer Program, and PhD student at Imperial College London, recently made a groundbreaking contribution to the way scientists think about climate change and the CO2 fertilization effect. In this interview he discusses his research, his first publication in Science, and his summer project at IIASA.

Conducted and edited by Anneke Brand, IIASA science communication intern 2016.

César Terrer ©Vilma Sandström

César Terrer ©Vilma Sandström

How did your scientific career evolve into climate change and ecosystem ecology?
I studied environmental science in Spain and then I went to Australia, where I started working on free-air CO2 enrichment, or FACE experiments. These are very fancy experiments where you fumigate a forest with CO2 to see if the trees grow faster. In 2014 I moved to London for my PhD project. There, instead of focusing on one single FACE experiment, I collected data from all of them. This allowed me to make general conclusions on a global scale rather than a single forest.

You recently published a paper in Science magazine. Could you summarize the main findings?
We found that we can predict how much CO2 plants transfer into growth through the CO2 fertilization effect, based on two variables—nitrogen availability and the type of mycorrhizal, or fungal, association that the plants have. The impact of the type of mycorrhizae has never been tested on a global scale—and we found that it is huge. I think it’s fascinating that such tiny organisms play such a big role at a global scale on something as important as the terrestrial capacity of CO2 uptake.

How did you come up with the idea? One random day in the shower?
Long story short, researchers used to think that plants will grow faster, and take up a lot of the CO2 we emit. They assumed this in most of their models as well. But plants need other elements to grow besides CO2. In particular, they need nitrogen. So scientists started to question whether the modeled predictions overestimated the CO2 fertilization effect, because the models did not consider nitrogen limitation. To find out, I analyzed all the FACE experiments and indeed I saw that in general plants were not able to grow faster under elevated CO2 and nitrogen limitation. However, in some cases plants were able to take advantage of elevated CO2 even under nitrogen limitation. I grouped together the experiments where plants could grow under nitrogen limitation and after a lot of reading I saw what they had in common: the type of fungi! It turned out that one type of mycorrhizae is really good at transferring large quantities of nitrogen to the plant and the other type is not.

How did that feel?
Awesome! When I saw the graph, I knew: this is going to be important. Of course, after this, my coauthors helped me to polish the story. Without them, the conclusions would not be as robust and clear.

So how does this process work? Where do the fungi get the nitrogen from?
Particular soils might have a lot of nitrogen, but the amount available for plants to absorb might be low. Also, plants have to compete with non-fungal microorganisms for nitrogen. So if there is not much there, the microorganisms take it all. It’s called immobilization. Instead of mineralizing nitrogen, they immobilize it so that plants cannot take it up, at least not in the short term. Some types of fungi are much more efficient in accessing nitrogen, and associated with roots they allow plants to overcome limitations.

Nitrogen mobilization abilities of different types of fungi. Growth of plants associated with fungi not beneficial for nitrogen uptake (illustrated as grass roots on the left) could be limited by low nitrogen availability in soil. Other plants have the advantage of increased nitrogen uptake due to their beneficial association with certain types of fungi (illustrated as yellow mushrooms connected to the roots of the tree on the right). ©Victor O. Leshyk.

Nitrogen mobilization abilities of different types of fungi. Growth of plants associated with fungi not beneficial for nitrogen uptake (illustrated as grass roots on the left) could be limited by low nitrogen availability in soil. Other plants have the advantage of increased nitrogen uptake due to their beneficial association with certain types of fungi (illustrated as yellow mushrooms connected to the roots of the tree on the right). ©Victor O. Leshyk.

What is the impact of your findings?
Plants currently take up 25-30% of the CO2 we emit, but the question is whether they will be able to continue to do so in the long term. Our findings bring good and bad news. On the one hand, the CO2 fertilization effect will not be limited entirely by nitrogen, because some of the plants will be able to overcome nitrogen limitation through their root fungi. But on the other hand, some plant species will not be able to overcome nitrogen limitation.

There was a big debate about this. One group of scientists believed that plants will continue to take up CO2 and the other group said that plants will be limited by nitrogen availability. These were two very contrasting hypotheses. We discovered that neither of the hypotheses was completely right, but both were partly true, depending on the type of fungi. Our results could bring closure to this debate. We can now make more accurate predictions about global warming.

What will you do at IIASA and how will you link it to your PhD?
I want to upscale and quantify how much carbon plants will take up in the future. If we are to predict the capacity of plants to absorb CO2, we need to quantify mycorrhizal distribution and nitrogen availability on a global scale. We are updating mycorrhizal distribution maps according to distribution of plant species. We know for instance that pines are associated with ectomycorrhizal fungi and always will be. To quantify nitrogen availability we use maps of different soil parameters that are available on a rough global scale.

© Adam Edwards | Dreamstime.com

© Adam Edwards | Dreamstime.com

About César Terrer
Prior to his PhD, Terrer studied at the University of Murcia in Spain and the University of Western Sydney in Australia.

Currently he is a member of the Department of Life Sciences at Imperial College London, UK. For this study he collaborated with researchers from the University of Antwerp, Northern Arizona University, Indiana University and Macquarie University.

In the IIASA Young Scientists Summer Program, Terrer works together with Oskar Franklin from the Ecosystem Services and Management Program and Christina Kaiser from the Evolution and Ecology Program.

Further reading

 

Note: This article gives the views of the interviewee, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

How coordination can boost the resilience of complex supply chains

By Célian Colon, PhD student at the Ecole Polytechnique in France & IIASA Mikhalevich award winner

How can we best tackle risks in our complex and interconnected economies? With globalization and information technologies, people and processes are increasingly interdependent. Great ideas and innovations can spread like wildfire. However, so can turbulence and crises. The propagation of risks is a key concern for policymakers and business leaders. Take the example of production disruption: with global supply chains, local disasters or man-made accidents can propagate from one place to another, and generate significant impact. How can this be prevented?

Risk propagation is like a domino effect. Credit: Martin Fisch (cc) via Flickr

Risk propagation is like a domino effect. Credit: Martin Fisch (cc) via Flickr

As part of my PhD research, I met professionals on the ground and realized that supply risk propagation is a particularly tricky issue, since most parts of the chains are out of their control. Supply chains can be very long, and change with time. It is difficult to keep track of who is working with whom, and who is exposed to which hazard. How then can individual decisions mitigate systemic risks? This question directly connects to the deep nature of systemic problems: everyone is in the same boat, shaping it and interacting with each other, but no one is individually able to steer it. Surprising phenomena can emerge from such interactions, wonderfully illustrated by bird flocking and fish schooling.

As an applied mathematician thrilled by such complexities, I was enthusiastic to work on this question. I built a model where firms produce and interact through supply chain relationships. Pen and paper analyses helped me understand how a few firms could optimally react to disruptions. But to study the behavior of truly complex chains, I needed the calculation power of computers. I programmed networks involving a large number of firms, and I analyzed how localized failures spread throughout these networks, and generate aggregate losses. Given the supply strategy adopted by each firm, how could systemic risk be mitigated?

With my collaborators at IIASA, Åke Brännström, Elena Rovenskaya, and Ulf Dieckmann, we have highlighted the key role of coordination in managing risks. Each individual firm affects how risks propagate along the chain. If they all solely focus on maximizing their own profit, significant amounts of risk remain. But if they cooperate, and take into account the impact of their decisions on the risk profile of their trade partners, risk can be effectively mitigated. Reducing systemic risks can thus be seen as a common good: costs are heterogeneously borne by firms while benefits are shared. Interestingly, even in long supply chains, most systemic risks can be mitigated if firms only cooperate with only one or two partners. By facilitating coordination along critical supply chains, policy-makers can therefore contribute to the reduction of risk propagation.

Colon's model analyzes how firms produce and interact through supply chain relationships. Credit: Jan Buchholtz (cc) via Flickr

Colon’s model analyzes how firms produce and interact through supply chain relationships. Credit: Jan Buchholtz (cc) via Flickr

Drawing robust conclusions from such models is a real challenge. On this matter, I benefited from the experience of my IIASA supervisors. Their scientific intuitions greatly helped me focusing on the most fertile ground. It was particularly exciting to borrow techniques from evolutionary ecology and apply them to an economic context. Conceptually, how economic agents co-adapt and influence each other shares many similarities with the co-evolution of individuals in an ecological environment. To address such complex issues, I strongly believe in the plurality of approaches: by illuminating a problem from different angles, we can hope to see it more clearly!

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

Climate change, bioenergy, and ozone in the EU

By Carlijn Hendriks, Netherlands Organization for Applied Scientific Research (TNO) & IIASA Peccei award winner

Last summer, I participated in IIASA’s Young Scientist Summer Program, working with the Mitigation of Air Pollution and Greenhouse Gases and Ecosystems Services and Management programs. My research focused on what impacts the EU climate and air quality policy could have on ground level ozone around the middle of this century. While clean air policies should help reduce the pollution that can lead to ozone formation, we found that that climate change and energy policies will still increase ozone concentrations and damage by mid-century, unless stricter air pollution measures are implemented.

Ozone forms through reactions of various pollutants - a process that speeds up at higher temperatures. © Damián Bakarcic via Flickr

Ozone forms through reactions of various pollutants and chemicals in the atmosphere – a process that speeds up at higher temperatures. © Damián Bakarcic via Flickr

Ozone at ground level is an air pollutant, causing health and ecosystem problems. It is also an important component of summer smog. Ozone is not emitted into the atmosphere directly, but is produced when volatile organic carbons are oxidized in the presence of  nitrogen oxides and light. Nitrogen oxides are released into the atmosphere mainly as a result of combustion processes (like car engines and industry), while non-methane volatile organic carbons (NMVOCs)  come in large part from vegetation, especially broad-leaf trees and some fast-growing crops.

Part of the EU energy policy is to stimulate the use of sustainable biomass as an energy source. This could lead to expansion of commercial bioenergy crop production in plantations and an increasing use of  forests. While this may help to reduce greenhouse gas emissions, it will also increase NMVOC emissions. At the same time, EU air quality policies aim to reduce emissions of air pollutants such as nitrogen oxides and man-made NMVOC. Because some steps in the ground level ozone formation process are driven by absorption of light and/or proceed faster with higher temperatures, climate change could lead to higher ground level ozone concentrations in the future.

The separate effects of these three trends on ground level ozone have been studied before, but the question remains: what will be the combined impact of a) an increase of bioenergy plantations, b) EU’s air quality policy and c) climate change on health and ecosystem damage from ground level ozone? And which of the trends is the most important? To answer these questions, I used three models to study two energy and air quality scenarios for Europe under current and possible future climate conditions.

Two energy scenarios calculated by the Price-Induced Market Equilibrium System (PRIMES) model form the basis of this work. We used a reference scenario and one in which Europe reaches 80% CO2 emission reduction in 2050. These energy scenarios were used as a basis to calculate air pollutant emissions with IIASA’s  Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model. Then we put the same scenarios into IIASA’s Global Biosphere Model GLOBIOM to obtain the change in land cover because of increasing bioenergy demand. I combined these datasets in chemistry transport model LOTOS-EUROS (the model of choice at my home institute, TNO) to calculate the impact on ground level ozone concentrations across Europe. To simulate ‘future climate’ we used the year 2003, in which Europe had a very warm summer, with temperatures 2-5 °C higher than normal.

Difference in average ozone concentration (in µg/m3) between the current situation and the 80% CO2 reduction scenario in 2050 under future climate change conditions for the period April-September. Negative numbers mean a decrease in ozone levels.

Difference in average ozone concentration (in µg/m3) between the current situation and the 80% CO2 reduction scenario in 2050 under future climate change conditions for the period April-September. Negative numbers mean a decrease in ozone levels.

We found that especially for the CO2-reduction scenario, the increase in bioenergy production could cause a slight increase in ozone damage. However, the impact of reduced emissions because of more stringent air quality policies far outweighs this effect, leading to a net reduction of ozone damage. The third effect, more efficient ozone formation in a warming climate, is so strong that in 2050 ozone damage to human health could be worse than today, especially for northwestern Europe. Stringent air quality policies close to a maximum feasible reduction scenario would be needed to make sure that health and ecosystem damage towards the middle of the century is smaller than it is today.

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

Interview: Can nature bounce back?

Jesse Ausubel is director of the Rockefeller University Program for the Human Environment. He was a participant in one of the first classes of IIASA’s Young Scientists Summer Program (YSSP).

Please tell us about your current job – what is your major area of focus?
I do research and manage research.  My research primarily concerns sparing natural resources through changes in technology and consumer behavior.  The main projects I help manage are the Deep Carbon Observatory  (concerned with the origins of life and hydrocarbons) and the International Quiet Ocean Experiment (aiming to achieve a better soundscape of the oceans, including human additions of noise).

In your recent paper, Nature Rebounds, you present a hopeful view of environmental change which contrasts with many other views of the future. What makes you think your view is possible?
The paper looks objectively at the peaking of demand for many natural resources that has occurred in the USA and elsewhere since about 1990.  Demand for water, energy, land, and minerals is softening, while demand for information continues to soar.  Fortunately, information brings precision in production and consumption and spares other resources.  The result is, for example, huge regrowth of forests.  The global greening, or net growth of the terrestrial biosphere, allows re-wilding.  Ecological restoration inspires many people, although learning again to live in proximity to bears and wolves is not simple.

The American bald eagle population has recovered from endangered status. Photo: US Fish and Wildlife

The American bald eagle population has recovered from endangered status. Photo: US Fish and Wildlife

What would be the key changes humanity would need to make for this vision to come true at a global scale?
Most of what happens is not because humanity consciously and deliberately strategizes and makes changes.  The role of policy is vastly exaggerated.  French intellectual Bertrand de Jouvenel wrote in his profound 1945 book, Du Pouvoir, “politics is the last repository of hope. “ High tech tycoons Steve Jobs (Apple) and Jeff Bezos (Amazon) popularized tablets and e-readers and did more, together with the innovators in e-mail, to spare forests than all the forest activists and UN targets.  Good systems analysts find high leverage for sound directions like decoupling and recycling. Simply observing well, describing the world as it is, matters greatly and demands tremendous skill and dedication.

Ausubel wears the ribbon of the International Cosmos Prize, which he shared with other leaders of the Census of Marine Life program. Photo courtesy Jesse Ausubel

Ausubel wears the ribbon of the International Cosmos Prize, which he shared with other leaders of the Census of Marine Life program. Photo courtesy Jesse Ausubel

Please tell us about your YSSP work at IIASA? What were your questions, and what did you find?
I participated in the 1979 YSSP, the second class.  IIASA’s energy group had developed scenarios of how human activities might change climate. My task was to explore impacts of climate and adaptations.  The 1980 book Climatic Constraints and Human Activities summarizes much of what we learned. Most of the book still reads well.  Following climate today, I am reminded of the remark, “Everything has been said, but not everyone has had a chance to say it.”

How did the YSSP influence your career?
My YSSP summer encouraged a big drop in my disciplinary and national prejudices. My chief, Soviet hydrodynamicist Oleg Vasiliev, had great intellectual integrity.  We had a wonderful rapport and in fact in July I sent him best wishes for his 90th birthday.  Oleg invited me to stay in Laxenburg for two more years, which opened more avenues, most importantly collaborations with Cesare Marchetti, Nebojsa Nakicenovic, and Arnulf Gruebler which continue today. The YSSP class itself was lively and talented; John Birge, for example, has had a great career in operations research.  Finally, IIASA showed me the value of scientific cooperation between nations in conflict, and I have actively supported such cooperation ever since.
Reference
Ausubel, Jesse H. 2015. “Nature Rebounds.” Long Now Foundation Seminar, San Francisco, 13 January 2015. http://phe.rockefeller.edu/docs/Nature_Rebounds.pdf.

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

The city resilient – some systems thinking

By Bruce Beck, Imperial College London and Michael ThompsonIIASA Risk, Policy and Vulnerability (RPV) Program.

What do Arsenal’s Emirates Stadium in London, the now glorious heritage of Islington’s housing stock, and the cable-car system in Kathmandu for getting milk supplies to that city, all have in common?

An aerial view of the Emirates Stadium and surrounding area (credit: Peter McDermott/CC BY-SA 2.0)

They are (or were) all transformative in their own way. All are commendable outcomes from the process of city governance that we argue will be essential for Coping with Change, the subject of our working paper for the Foresight Future of Cities project. Each is a primary case study in the analysis of our paper. We call this kind of governance ‘clumsiness’. It is something that does not evoke any sense of the familiar attributes of suaveness, elegance, and consensuality implied and valued in most other kinds of governance. So what, then, makes this thing with such an awkward, provocative name so relevant to the future of cities?

Before and after: Islington’s clumsy and resilient resurgence.

Imagine the city being buffeted about by all manner of social, economic, and natural disturbances over time. There will be times for taking risks with the city’s affairs, and times for avoiding them, or managing them, even just absorbing them – 4 mutually exclusive ways of apprehending how the world works, as it were, and 4 accompanying styles of coping.

In the financial industry, this risk typology has been referred to as the 4 seasons of risk. These are strategically and qualitatively different macroscopic regimes of system behaviour; coping with change between one and another of them is every bit as strategically significant. Conventionally, we recognise only 2 of these regimes: those giving rise to boom and bust in the economy. They reflect just 2 of the 4 ways of understanding the world and acting within it. The nub of the distinctive advantage of clumsiness over other forms of governance for coping with change and transformation is the richness of its (fourfold) diversity of perspective, from which may derive resilience and adaptability in the city’s response to any disturbance – big or small, economic, social, or natural.

Clumsiness is most assuredly deeply participatory. Its process is assiduously supportive of robust, noisy, disputatious debate: witness the gyrations in the Arsenal, Islington, and (especially so) Kathmandu case studies. This is exactly as one should expect of any meaningful engagement among the city’s stakeholders: the public-sector agencies, community activists, private-sector businesses, and so on, all with their own vested interests. The 4 ways of seeing the world are mutually opposed; each is sustained in its opposition to the others, as will be the shaping of their aspirations for the future. Each needs the challenges from the others, not least to avoid the ‘group-think’ in governance that is of such considerable concern to government in managing financial risk.

At the peak of deliberative quality in governance, all 4 outlooks are granted access and responsiveness in the debate, in the process of clumsiness, in other words, in coming to a decision or policy — with ever higher social consent. And in the clumsiest of outcomes, each opposing group gets more of what it wants, and less of what it does not want, at least for a while, until everything about the city’s affairs is revisited once again, as the various seasons of risk come around, each holding sway in turn. As we say in our working paper, clumsiness is why village communities in the Himalayas and Swiss Alps have remained viable over the centuries, without destroying either themselves (‘man’) or their environments (‘nature’) – sustainability par excellence, in other words.

So now we must ask: can cities be viable and sustainable in the same way as these mountain villages? In particular, how can the city’s built environment – the infrastructure that mediates between nature and man, the natural and human environments – be made resilient and adaptable, especially in an ecological sense? Thus might we possess this much prized attribute of systems behaviour in each of the natural, built, and human environments, and in a mutually reinforcing manner. What role might clumsiness have in all of this?

In closing our working paper, where we “connect the systemic dots” of our entire argument, we touch upon a computational foresight study in seeking a smarter urban metabolism for London. The fourfold typology of clumsiness is employed to define future target aspirations for the city (quantitatively expressed, under gross uncertainty). These should be the distant outcomes of the fourfold narratives of how the world is believed to work and what it is that each attaching vested interest much wants – and decidedly does not want. An inverse sensitivity analysis (redolent of a computational backcasting) identifies what is key (and what redundant) to the ‘reachability’ (or not) of each of the 4 sets of aspirations for the distant future. Imagine then the urine-separating toilet (UST) as the clumsy solution to a smarter metabolism for London – a smarter way, that is, of the city’s processing of the resource flows of water, energy, carbon, nitrogen, and phosphorus passing through its social-economic life. Rather more grandly put, imagine instead the UST as a “privileged, non-foreclosing policy-technology innovation” for today!

Well now … if clumsiness is such a jolly good thing, what else might it do for us and our cities? We submit it promises the prospect of greater resilience and adaptability in the governance of innovation ecosystems, extending thus the lines of evidence recounted for re-invigoration of the industrial economy of NE Ohio in Katz & Bradley’s recent (2013) book Metropolitan Revolution. ‘Resilience’ and ‘ecosystem’ are (for now) ubiquitous in our everyday language. But no-one, as far as we are aware, has thought of applying the immensely rich notion of ecological resilience to orchestrating the creative and clumsy affairs of an innovation ecosystem. We are currently examining this.

Read the full report

Featured image by Peter McDermott. Used under Creative Commons.

For further information on the Foresight Future of Cities project visit: https://futureofcities.blog.gov.uk

Interview: Coal, natural gas, and clean air for China

Jun Liu, a PhD student at the College of Environmental Sciences and Engineering in Peking University, Beijing, China, has won the annual Mikhalevich Award for her outstanding research as part of the 2014 Young Scientists Summer Program (YSSP) in IIASA’s Mitigation of Air Pollution and Greenhouse Gases research program.

Jun Liu, second from right, at the YSSP award ceremony in August 2014.

Jun Liu, second from right, at the YSSP award ceremony in August 2014.

Could you tell me a bit about yourself? Where are you from and what do you study?
I’m a fifth-year PHD student from College of Environmental Sciences and Engineering in Peking University, Beijing, China. My major is Environmental Sciences. My main fields of scientific interest include source of air pollution, regional air quality modeling, mitigation policy and health effects of atmospheric air pollutants.

Why did you apply to the Young Scientists Summer Program?
For a long time before the YSSP, I had read many excellent research papers on the RAINS and GAINS model. It was developed at IIASA. I hoped to have chance to utilize the model in my research. At the same time, I was so lucky to learn about YSSP application from my supervisors when I was visiting in Princeton University in winter 2013. So I applied for the program.

Please tell me about your research project: What was the question you were trying to answer?
In the background of Russian-China gas deal signed in May 2014, we wanted to discuss and compare the potential air quality benefits for coal substitution strategies between power plants, industrial boilers, and residential cooking and heating activities.

What did you find?
We found that whereas more efforts were directed at the power sector, replacing coal in power sector is actually the least effective strategy to reduce pollutants emissions. Instead, coal substitution in the residential sector achieves the highest potential for emission reduction and air quality benefits.

Thick air pollution is a common problem in many areas of China. Credit: V.T. Polywoda via Flickr.

Air pollution is a serious and growing problem in many areas of China. Credit: V.T. Polywoda via Flickr.

Why is this research important for policy or society?
As we know, China is facing serious air pollution problems. Replacing coal with natural gas is one of the important strategies to reduce this air pollution. Historically, the power sector is the largest coal consumer and receives highest priority for reducing coal use, but the residential sector is scarcely discussed. It is an urgent time for China to propose a rational and effective distribution plan across different sectors for our limited natural gas resources.

My study shows that informed decision making should direct strategies to maximize the air quality and human health benefits, rather than focusing on the control of coal consumption. From this perspective, the residential sector is more promising than power sector and industrial boilers.

How are you planning to continue this research when you return to IIASA?
I plan to finish writing papers for the natural gas scenarios and continue with other policy relevant work, such as potential role of agricultural ammonia emission in air pollution in China.

What was your favorite aspect of the YSSP and IIASA?
First, The YSSP encourages an interdisciplinary perspective and integrated method. Second, we have lots of opportunities to improve our research through discussions with our research teams, our supervisors at IIASA, and experts in other fields who are also at IIASA.  Also we can communicate and learn from other YSSPers to improve our work. The three-month length of the program is highly productive and effective.

What was your favorite moment of the summer?
 There were many moments: I particularly enjoyed the many discussions with my supervisors and my colleagues in my research program, the unforgettable trip with YSSPers to Hallstatt, Asia Day, and the awards ceremony.

Jun Liu, seated at left, and her colleagues in the Mitigation of Air Pollution and Greenhouse Gases research program

Jun Liu, seated at left, and her colleagues in the Mitigation of Air Pollution and Greenhouse Gases research program