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Valérie Masson-Delmotte
4 February 2016 13:35

The Carbon Brief Interview: Valérie Masson-Delmotte

Roz Pidcock


Roz Pidcock

04.02.2016 | 1:35pm
InterviewsThe Carbon Brief Interview: Valérie Masson-Delmotte

Dr Valérie Masson-Delmotte is a senior researcher at the Laboratoire des Science du Climat et de l’environnement in France and a specialist in reconstructing past climate variability from ice cores. In October 2015, she was elected as the new co-chair of Working Group One of the Intergovernmental Panel on Climate Change (IPCC), the group which examines the physical science basis. Having served as coordinating lead author on the paleoclimate chapter in the Fifth Assessment Report (AR5), she will now lead Working Group One’s activities for the Sixth Assessment Report (AR6) cycle.

CB: The IPCC has a new chair, a new leadership team, and the scoping for AR6 [the Sixth Assessment Report] is underway. Do you yourself see this as a new beginning for the IPCC?

VMD: I think it’s an opportunity to better integrate across working groups from the beginning, from the scoping process. I think that’s our main challenge. [To] make suggestions for the panel that will help to better integrate, maybe starting from the – what we aim to deliver as a – synthesis report. And, you know, we can only make suggestions as co-chairs. So we are working on suggestions but the decisions, they belong to the panel. And one of the suggestions we would like to make would be to have a sort of synthesis product that would be like a special report in a way, embedded in the assessment, that would have a focus on the regional aspects, and that would integrate across Working Groups I, II & III. So, this would build from what today is the last chapter of Working Group I, the regional dimension, [and] the regional volume of Working Group II. It would be more a challenge for Working Group III probably, focusing on the regional dimension, because a lot of what they explore is global – you know, emerging technologies, market-driven development, and things like that. But there are dimensions that are regional, for instance, related to policies, assessment of policies for instance.

CB: So, when you talk about better cross-working between the working groups, is that something that you think has been hindering things so far? How much of a priority is it for you that that happens?

VMD: The problem is to have an integration pathway that goes from the scoping to the writing, exchange of information amongst authors of different working groups. Even amongst, you know, co-chairs and vice-chairs of all working groups, which is a real challenge, given the workload that today exists on individual authors. So, we think that if we start by identifying key pathways to reach that target, it would facilitate the process. And for instance, our first priority now is not to work on the scoping of the full assessment report but to explore the 23 suggestions of special reports. And what we decided amongst the three working group co-chairs, was to write a two-page commentary following IPCC guidelines, so looking at the science part. Were there gaps in AR5 [the Fifth Assessment Report] on given topics? Is there sufficiently new science to motivate an assessment of a given topic? And what are the implications of selecting a given topic for a special report for the sixth assessment, or vice versa? If the topic is not selected as a special report, how can we handle that in the scoping of the Sixth Assessment report? And the way we want to do that, to integrate across working groups, is that the commentaries will be written together by vice-chairs and co-chairs of the three working groups. So we will identify volunteers [laughs], and try to integrate as early as this first action.

RP: So the topics haven’t been decided yet, the selection hasn’t been made?

VMD: There are 21 proposals that were received and are available on the website of IPCC. They were available from the plenary in Dubrovnik and since that time, two new proposals are in the pipeline. One on cities and one on glaciers – sorry, mountains. And so altogether we have 23 different proposals and we aim to provide two-page commentary, at most, on each of the proposals. That will be available ahead of the next bureau meeting that will take place in mid-February. And then the bureau maybe [will] make or decide priorities to propose to the panel, or a strategy to propose to the panel, that will take place in Nairobi in April.

CB: Can you say what your priority topics would be?

VMD: We have identified nine clusters of proposals. It doesn’t mean any priority. But there are a number of proposals related to land-use; agriculture, land-use, carbon sequestration, forestry, desertification and drought, land degradation. So, there’s a whole set of topics related to the land surface in general. If I can make a very brief comment, I would say that this corresponds also to a gap in AR5. Especially for the low-carbon pathways, which imply land carbon sequestration, and the way they were handled in the RCP [Representative Concentration Pathway] scenarios used in Working Group I. So, there’s clearly something where there is a need to better integrate the different pieces, the socioeconomic pathways on one side and how you drive simulations on the other side, and then what is also happening, really. Then the second group of proposals are related to cryosphere and sea level, ocean, shipping. So, these are all closely related. There were a number of events here at COP21 on these topics. In the draft Paris agreement of Saturday, there was not the word ‘ocean’. So, it seems that there is a challenge that policymakers incorporate ocean in the way they perceive climate-related issues. Then I need to take my computer to look at the rest of the proposals…

CB: You mentioned low-carbon pathways and actually there’s a lot of talk, there’s an increasing focus on 1.5C…

VMD: That’s one of our clusters. It’s a proposal that was already raised by UNFCCC [United Nations Framework Convention on Climate Change] to IPCC to produce a special report on 1.5C warming and impacts, and pathways compatible with the target. It was reintroduced in the draft Paris treaty of last Saturday.

CB: How likely is it that that will end up being a topic, given that it’s been requested by the UNFCCC?

VMD: I think the decision belongs to the IPCC panel. There is an overlap with government representatives present here as well. Our work is to inform that topic as a special report based on new science since AR5 – is there sufficiently new science to motivate authors, scientists, to work hard to produce a new assessment report? So there are – I mentioned some of the things, carbon sequestration, the way it’s handled, thresholds with respect to impacts. Probably on the science side, what could be more interesting than just focus on 1.5C, it could be to investigate impacts and threshold for different long-term targets: 1.5C, 2C, 2.5C, 3C. There are methodologies that are emerging to make use of all projections, not looking at them as a function of the date in the future but looking at the impacts when, in each simulation, you reach 1.5, 2, 3C of global warming. So, another way of aggregating existing model outputs.

CB: Can you give a flavour of what the difference in terms of impacts might be with 1.5C as opposed to 2C?

VMD: What I personally see, that has emerged since AR5, are two lines: one related to ice sheets and sea level. Almost each month you have a new paper with new methodologies on that topic. And the second line of new information comes from the work on marine ecosystems. Especially, a review paper last July in Science that suggested more vulnerability than reported in AR5 for some aspects. But these are just two examples.
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CB: From your own perspective, what do you understand about how feasible a 2C 1.5C pathway is? They both rely heavily on negative emissions, Bioenergy with Carbon Capture and Storage (BECCS).

VMD: We need to work on, you know, also the physical and biological science basis on biomass productivity. Because in economic models, it seems to me that it is sometimes an adjustment parameter where you can add negative emissions to meet a given target. The next question is, is it feasible? What are the implications for other aspects related to land use, agriculture and food security, biodiversity considerations, for instance? So, these are really interesting topics at the crossroads between energy, water and land use. But can you repeat your question, because something came to my mind and I think I forgot it…

CB: Yeah. The question was from your own perspective, what do you understand about the feasibility of 2C and 1.5C?

VMD: Yes. Also, there’s one thing that’s really relevant for Working Group I on that topic, a couple of things. Thinking of really the low end scenarios, what’s emerging with respect to climate sensitivity and transient climate response. There are lots of efforts engaged by the World Climate Research Programme [WCRP] – that’s one of their key challenges. So there’s also emerging information on that part. A second important point on the perspective of Working Group I is aerosols and the way they are handled in the RCP2.6 scenario, for instance. This has huge implications on the, you know, below 2C or below 1.5C simulations. So, these are things that need to be addressed, I believe. Either in the special report or in the next sixth assessment framework.
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CB: How quickly do you see the uncertainty around climate sensitivity narrowing?

VMD: There have been a number of studies that work at the process scale, especially the relationship to convection. And then propagate the information provided by studies at the process scale to evaluate the model skills, and then propagating model behaviour from the process scale to the climate sensitivity. That’s what I see as [an] emerging new constraint.

CB: Do you have a feeling yourself about what the real-world value is for climate sensitivity? What point is it likely to narrow on?

VMD: I cannot make, you know, just give a number like that. What I can say is that the low end values reported in AR5 are probably too low. And this is based on these emerging process studies. I know WCRP, for instance, aims to produce their own assessment with respect to climate sensitivity. And that would probably be a very important piece of work for whatever IPCC decides to do with respect to that topic.

CB: So, the range as it stands is 1.5-4C…

VMD: Yes, and the 1.5C and 4C – the low and high ends – they are partly constrained by palaeoclimate data, at least that was the way it was refined, in a way, in AR5. And probably what’s emerging now are process-based studies that may also allow to narrow slightly the end values.

CB: Is 2C likely to be too low as well, or is it just the very lower boundary that you think is emerging as too low?

VMD: I cannot say with the precision of half a degree. And I think so far, from what I have seen, there has not been any comprehensive study that would allow to produce an informed number. I have a feeling that probably values between around 2.5C or more may be more realistic. And that’s also based on revised information for changes in tropical sea surface temperatures in the past that are critical to constrain the low end values as well.

CB: One thing the IPCC says – a characteristic of the IPCC – is to be policy-relevant but not policy prescriptive. You’ve talked a lot about connecting the Working Groups – how important do you think that is? Or to put another way, do you think those definitions of policy relevant and policy prescriptive have changed?

VMD: I don’t think so because the IPCC is looking at different options, always. And that’s the best way to convey scientific information. What I think is that IPCC was successful at, in a way, was interacting with international policies. Being relevant for international policies. I mean, that is also the link with UNFCCC. What was less efficient was engaging with local policy makers, providing relevant information for local policymakers and also engaging with engineers who are at play for local city planning, coastal planning etc. So I would see, myself, these as a key role for the sixth assessment report, to provide relevant information at the more regional scale. And we know this local scale is critical both for adaptation and mitigation.

CB: Related to that, perhaps – the new chair, Hoesung Lee, has said that he wants a solutions focus for the next IPCC report. Do you think there has been too much focus on problems rather than solutions?

VMD: It’s a difficult question. I think there has always been…I think communication has always been in the two ways: looking at the worst-case scenario that nobody would like to live and, at the same time, showing that there are alternative pathways that also do not represent [a] dramatic cost to implement. And that was already present in the first IPCC assessment. But I would come back to that point about solutions. I think it’s easy to address solutions from a Working Group Two perspective, about adaptation, and limits to these solutions. It’s also quite easy for Working Group Three to produce pathways that are showcases for solutions. What’s very difficult is to show how you implement the solutions? What are the barriers that you have to work with? What are examples of success, where solutions were implemented as quickly as required, for instance, with respect to long-term climate targets? So, I see the question of solution also related to the barriers for the deployment of solutions. And the point about solutions is really a little critical with respect to Working Group I because it gives a feeling that climate science, physical climate science, is only looking at problems. But I believe that more informed projections with a way to track the sources of spread from the process scale to the regional impact dispersion scale is also part of the solutions. So, guiding users of climate information into the best informed views of climate projections.

CB: We’ve talked about the special reports and the new focus on solutions. What else will be new for AR6?

VMD: What else will be new will depend on the choice of special reports and will depend on the scoping of the full document. I can give you a view personal views. I think we clearly have to improve the communication, not to policymakers but to a broader audience. One suggestion that was raised here was to have a Summary for Citizens of the World and not only a Summary for Policymakers. I think we have also to show the diversity of authors involved in the IPCC report – to avoid a perception of, you know, experts in the sky and not in the real world. So, also show the diversity of people involved in the report and we try to develop a model for that in the French side. So, for instance, we released a resource where you can navigate in the policymakers of the Synthesis Report, where you have the text figures… [and]…videos of scientists, either authors or not, that explain the figures – how they are made, what they mean, what is the relevance – but with a human face. And I find that’s quite helpful in communicating IPCC findings, not only as text and figures.

CB: This is something you’ve developed since AR5?

VMD: It’s just online, it’s in French at the moment but I use that, I see that as a sort of model of what could be produced. So, these are part of the options. I would like to develop online tools before the scoping process to inform scientists about what is a climate assessment? What is the role of different types of authors and review editors and reviewers? [To] have different authors from different countries, genders and ages explain the amount of work – because it has to be very clear, it’s a huge work at different times. But also explain the added value for themselves to contribute to IPCC, not only for IPCC itself but for their own work as researchers or teachers. Because in Working Group I, we have a very specific problem. We are the working group with the least proportion of authors from developing countries and this is not acceptable. So, we need to engage with early career scientists in different ways than the usual scoping process.

CB: When we interviewed the IPCC chair candidates, something that surprised most of them, I think, is that Working Group I was the actually the only working group to spend all of its communications budget for AR5.

VMD: Yes, Thomas Stocker and Qin Dahe I think had a lot of thoughts about how to better communicate…

CB: And will that continue?

VMD: I hope so. The TSU [Technical Support Unit] will be funded by the French government so we will have French standards, not Swiss standards. So, we will try to have a model that is low-cost.

CB: What does that mean, French standards rather than Swiss standards?

VMD: We won’t have the same budget as the Swiss had for the TSU of Working Group One. But I would also like to follow some ideas developed in Working Group 2 and 3. For instance, having chapter assistance based on volunteers that can contribute and be associated to the work of IPCC. I think it’s a nice way to engage with early career scientists and the model was tested by Working Groups Two and Three. So, that’s another example. And then we have really the question of the structure of the Working Group One report, when you said what will be new. I think it will be very difficult to motivate authors to continue to contribute to a report that is so thick, that is so broad and that follows always the scheme where you have observations, processes and projections. So, we need to find the best way to work through observations, processes and model results. It’s a real challenge in the way we will define the structure of Working Group One. It is funny because when we had an informal ExCom [Executive Committee] meeting, many people said Working Group One, that’s easy – we’ll take the same model as AR4 and 5. The feedback I got from many scientists involved in AR5 and others was that it’s time to change.

CB: It’s fascinating. So, when we talk about communication we’re not just talking about the IPCC communicating its findings, you’re talking about between working groups and even within Working Group One?

VMD: Yes, how we propagate information between observations, process studies and the use of model results. One part of the last report that I found very difficult to read was the chapter on model evaluation. But that’s really critical, you know. How confident you are in a specific behaviour within climate models is really critical for all the other implications. So, we really need to think and work hard on how to improve, probably, this aspect of model evaluation, incorporating observations and model results. And I cannot provide you with an answer on how it will evolve but it clearly needs to be modified, I think. It doesn’t mean that I don’t acknowledge the very successful work of AR5 and Working Group One, that I found very mature. But maybe it’s also time to rethink what is expected of a climate assessment.

CB: Do you think there is a role for external parties? How much of the communication of the IPCC’s findings can be outsourced to science writers or graphic designers?

VMD: The model was the Frequently Asked Questions and I think it was very successful, so that’s an open question. We will have a workshop on communication in February and I think this will be a very valuable source of collective brainstorming on how to take best advantage of existing translators, also.

CB: Another question, perhaps about direction of travel…

VMD: I wasn’t…I stopped because I was thinking of something else.


VMD: There is something also that I’m personally interested in and from the work. I had a lot of discussions with all the vice chairs before our election and since the election, So, what I say is sometimes in agreement with them but not everything. So, it’s important to understand that I have sometimes ideas but all the decisions belong to, you know, group decisions. One idea I have, and which I think is accepted by the Working Group One bureau at the moment is to incorporate social scientists in Working Group One. And I see two lines: one is perception of climate change. It’s really important to have that feedback somewhere maybe in the first introductory chapter. Because we have facts, but at the same time we have to acknowledge that not everyone is sensitive to facts. Beliefs, values and ideologies can be a big filter for perception of facts. And I also see traditional knowledge as a contributor in data with gaps in observations: areas with low population density, with nomadic populations, mountain areas. I believe that there’s a growing literature on these two topics, perception and traditional knowledge, for which the next report can build on.

CB: You raised an interesting point there about how your own ideas fit in with the rest of the leadership team and the other working groups. How do you envisage that relationship working?

VMD: We already had a lot of discussions in Dubrovnik during the first meeting by email and in between because we have to define how we proceed with the special reports. We will have visual conferences and meetings regularly, and that’s how we will take decisions. I foresee that we will work on a consensus basis. I am really very happy by the bureau of Working Group 1 because there are scientists from different countries that have a very strong wish to be helpful and to be involved, you know, in shaping the best possible report we can produce.

CB: Until the day before the election, there were only male candidates for the chairship. Do you think that your appointment and those of Debra Roberts as Working Group 2 co-chair, Thelma Krug and Ko Barrett as vice chairs, do you think that’s starting to address the gender imbalance that was quite obvious within the IPCC?

VMD: I cannot tell you because I don’t know how the panel decides to make votes and I don’t believe the gender was the key priority at that stage. Because it was more about the regional balance, of course, especially for the vice-chairs…

CB: No, I’m not suggesting…

VMD: But I’m very happy that the gender balance has improved, it could not degrade, I think, from last time. I think I’m the second female co-chair of Working Group One, after Susan Solomon, probably. It’s a pity, you know. It’s a pity for the sixth assessment and I don’t know how best to work on that. The gender balance of AR5 authors was not satisfying, I believe. So, possibly having these online courses explaining what is a climate assessment, showing female scientists that have contributed, could help female scientists to project into that role. Because often what we see is that they would not apply. So we need to help, probably, some of the very good female scientists that exist – and there are many of them – to just apply. And if they apply, they have a good chance of being selected just because we try to improve the gender balance. And I was thinking, at the beginning my idea was that we should have something like a network of women in IPCC. Because it would be helpful both in showing women engaged in climate science, on one side. And also, at the same time, maybe communicating with women organisations worldwide, as a way to also communicate on climate research outputs. I’ve been involved in France…I got a prize for women scientists, which is a tool to promote women in science for, lets say, students and things like that. And through that I was involved in networks of women in engineering, women in entrepreneurship. And I thought that maybe that could be a way to engage with other audiences than the classical way of communicating. I don’t know if I have time and resources to do it!

CB: Let’s hope so…! So for all those female young career scientists, and all young career scientists really, perhaps you could just explain your background, how you got to this role?

VMD: My own background, I was trained in physics from a French engineering school with a specialisation in physics of fluids. Then I did a PhD thesis in past climate modelling with a focus on changes in African monsoons in a period called the Green Sahara period. And I was then very lucky to be hired immediately after my PhD thesis to work on past climate with Jean Jouzel, especially on ice core science. So I..and the tool I used for ice core science is the use of stable isotopes of water and for that I also work on present day observations, stable water isotopes in climate models and ice core data. So, I was lucky to be able to touch different timescales from weather to glacial-interglacial cycles and everything that’s in between, and also use data to test models. And also compare projected changes to past changes. I think it allowed me to touch different aspects of climate science. I’m also very personally engaged in outreach and education. I have written books for the general public and for children. It’s a very good test on the ability to communicate research results, especially with children.

CB: How do you explain climate change to children?

VMD: Depends on the aspect. For the greenhouse effect, for instance, I take the example of a blanket. It’s the simplest example and you can play it. Because it’s important to also have a physical sense of the processes at play. All experiments with the greenhouse effect are wrong. All the things we can do with a glass house, a greenhouse, are wrong. All simple experiments aiming to illustrate the greenhouse effect, for instance with a lamp and a glass box, are wrong and do not reflect the complex atmospheric radiative transfers. So, maybe the best example is a blanket.

CB: What do you think are the biggest unresolved questions in climate science? What would you like to see answered more than anything else?

VMD: I would not like to answer to that question, but maybe some of the key things that we will assess in AR6 are making sense of observed changes – so, the question of attribution. And I think in the past, there was a lot of statistical approaches involved in detection and attribution, and what’s emerging is a more physical based approach relating, for example, heavy rainfall events with warmer sea surface temperatures. And then the second step is, what explains the warmer sea surface temperatures, etc? And the role of land surface feedbacks in driving extreme temperatures? So, I believe that’s a vastly expanding path and also a very powerful way to communicate how climate science is working, the difference between weather and climate. I believe that will probably be strengthened in AR6, based on the emerging literature and also the need expressed by policymakers to make sense of what is already observed. And then about gaps? Probably one of the key gaps, one of the key open questions is the following: Do climate models correctly represent internal climate variability? It’s not simple to address but I think that’s a very important question. It’s explored and I think it’s a long-term topic.

CB: You mentioned attribution there and it’s a fascinating topic. Linking an event, while it’s still going on, with how much more likely that event is because of climate change is very powerful as a communication tool. Do you think people experiencing climate change in a real-time way like that helps make the issue a real one?

VMD: That’s another challenge, and it does not belong to IPCC. It’s a challenge of having research centres able to produce science diagnoses as quickly as possible, with respect to what’s happening in the real world. So, that does not belong to IPCC. And I can see that in the UK, for instance, a number of research centres are working on that. And it’s the case in many different countries, but not all have the capability to produce research at such real-time sense.

CB: There have been quite a lot of studies since AR5. Do you envisage AR6 as having a much chunkier section on single event attribution?

VMD: I believe in AR5, this was mostly the scope of the SREX report on extreme events. So it was not that much covered in AR5 by itself in the full assessment cycle. And I believe that it will have importance in AR6.
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CB: Another thing that people are talking a lot about at the moment is El Niño. It’s obviously nearing its peak now, what do you make of its behaviour over the last couple of years? It’s been a very will-it-won’t-it type story, and it’s ended up being a very big event.

VMD: I can formulate it the other way. I think one key question is: in a changing climate in response to human influence, how will climate variability change? And one question is ENSO, for instance. There have been a few papers coming out suggesting that there could be increased frequency of strong El Niños in a warming climate. So, this is emerging literature that’s very important for AR6. And I also think that this type of event is very interesting to test the ability to make seasonal forecasts, which is also part of the solutions that arise from climate science, I believe, at the interface between weather and climate. But I don’t believe that ENSO is a single key point. It’s very relevant for many places of the world, in the tropics, the Americas, Asia and also at the global scale. But explaining to people the role of modes of variability, not only ENSO but also Atlantic multi-decadal variability in the variability that they perceive, is also very important. What’s happening in the North Atlantic now is also a topic, a focus of attention with contrasting results appearing in the literature in the last month.

CB: What do make of conversations when you hear people talking about 2015 being the hottest year on record, or 2016 being the hottest year on record? How do those conversations fit into understanding more about natural variability cycles?

VMD: I think you have to explain to people that one of the ways IPCC presented model projections was very misleading. When we show projections, which is the multi-model ensemble, it suggests that you expect a sort of linear warming trend. That is, I think, very misleading. So, there’s a real need to explain how internal variability and also volcanic forcing and others will overlap to the long-term increasing trend due to more energy being trapped. The El Niño case is a good example of that at the global scale but the more you go to the regional scale, the more important is this internal variability. And there’s a clear need to better attribute the role of internal variability, or modes of variability, on what’s happening at the regional scale at not only annual but also decadal scales. And that’s a key challenge. better understanding that is also critical with respect to the overlap between predictions and projections. That’s really a very open field and I’m particularly frustrated when I see adaptation plans for different areas of the world where people use global projections as a guideline, but they don’t explore all the spread of what can happen locally if you consider internal variability on top of long-term trajectories driven by human activities. There’s really a need there to educate, also, planners involved in adaptation strategies on the whole spread of what could happen on timescales of years to decades. And in the Fifth Assessment Report, this was addressed in a chapter of Working Group One called near term projections, that was really based on emerging science. I don’t know how much more will be available for the Sixth Assessment Report, but that’s really a very important topic.

CB: Is it also important from a public understanding of climate change point of view, to also understand that?

VMD: Of course. Of course, at the regional scale, yes.
Main image: Valérie Masson-Delmotte, being interviewed at COP21, Paris, 9 December 2015.

This interview was conducted by Roz Pidcock on Wednesday 9 December 2015, mid-way through the second week of the COP21 climate negotiations in Paris.

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