 Sabine heads the Sustainable Resource Management and Global Change Working Group at the Mercator Research Institute. The title of Sabine's talk is Nature-Based, Engineer and Hybrid Solutions for Carbon and Level. What is state of the art? Sabine. Thank you very much. I'm sharing my screen now. So thank you for this kind invitation. I feel very honored that I'm invited to set a little bit the scene for discussing these different technologies and approaches for removing CO2 from the atmosphere in this second edition of the Stanford Carbon Management Workshop, of which I enjoyed the first part already very much. So I will also not touch too much base on the natural climate solutions as they have been covered in the first edition already, focused more on the engineered and hybrid solutions for carbon removal. Tried to give a little bit an idea of what is currently the state of the art without being able, of course, to go into that much detail that colleagues will be able to do tomorrow when there is a deep dive into some of these. Now the nice thing to speak after Chris, Rob and now also Jim is that I don't have to make big words anymore of why we actually need this. We've seen the 1.5 degree pathways from the IPCC special report, seeing this immediate turnaround of emissions, basically right now massive and rapid emissions reductions already before 2030 implying basically a retching up of the nationally determined contributions that nations have been putting on the table in the frame of Paris reaching net neutrality in around 2050. And then this is really the thing that I want to emphasize here. None of the pathways that we were able to assess in the special report could actually manage to reach the ambitious Paris goals that is being well below two degrees or even 1.5 degrees at the end of the century without withdrawing at least some CO2 from the atmosphere. So this is what I'm trying to illustrate here. On the left hand side, you see a scenario where explicitly there was an effort to reduce the dependence on carbon dioxide removal. And you see that still we dive under the zero line in the second half of the century. And also it means that we basically within a couple of years fall off the cliff pretty much and have to reduce residual emissions. Super rapidly. That's against a scenario where we have a little bit more flexibility, a little bit slower emissions reductions in the short to medium run, but that comes at the cost of making ourselves dependent on a lot more carbon dioxide removal. Plus we will then overshoot the temperature target. And that comes of course with higher uncertainties and higher risks associated with those higher temperatures during that time. So I know many of you are already experts at this but since I've been asked to set a little bit the scene let's start with what happens actually under climate change. And that will also help us later on to understand the accounting of different carbon capture and utilization pathways that were already a subject of the discussion and now in this workshop. So what happens is we take fossil fuels out of geological formations and then by using them we emit CO2 to the atmosphere and thereby cause global warming. Now if we substitute the fossil fuels with biomass then yes that biomass sequesters CO2 by means of photosynthesis but if we transform it into energy then we release it again to the atmosphere. So if everything works perfectly the best we could actually achieve would be a neutral outcome. The same can be said about combining carbon capture and storage with fossil fuels because then we only capture what we've previously been taking out of geological formations. Only if you don't let the previously sequestered CO2 from the biomass not escape back to the atmosphere but instead capture it and store it underground can we actually speak of a negative balance. This is the technology that has been prevalent in many of the scenarios you've been seeing in the previous slides in the global pathways also in the two degree pathways that were in the fifth assessment report already the combination of bioenergy with CCS short backs. And of course these could be many different technologies that could be backs associated with ethanol production that could be backs associated with combusting biomass in a combined heat and power plant. And that also explains the wide range of potentials and costs that I'll be showing you in a minute. Before that I wanna touch base on a couple of things that have surfaced in the talks already direct air-carbon capture and storage where you sequestered it or you take the CO2 directly out of the ambient air by means of a chemical reaction and then also the process of enhancing natural weathering processes where you grind a certain minerals very finely distribute them over larger areas so that they can react with the CO2 and permanently bind it. Both of those processes need a lot of energy. So you see that pretty much all of what I'm showing you has its respective bottlenecks. The last thing is the one that I won't say too much about it's basically enhancing our natural sinks the terrestrial sinks by planting for instance, additional trees, restoring ecosystems ocean sinks by fertilizing or enhancing alkalinity. And we'll be also hearing more from Pre-Smith tomorrow on changes in agricultural practices for instance to enhance soil carbon. So you see that I'm not mentioning everything that will also be a talk on mineralization tomorrow. And I'll also be touching on a CCU later on but let me first go to the typology that I think will be useful for the discussion. So we've seen Chris covering the natural a component of carbon dioxide removal already at the other side of the spectrum you have the technological solutions the engineered ones that I've covered here before in this illustration I have actually not talked about CO2 utilization we've seen that it has quite some prominence also in the pathways that Jim has been showing us and it's actually also part of the IPCC definition of carbon dioxide removal because it's not only anymore about storing CO2 underground or in oceans or in the biosphere, but it's also explicitly since the special report includes storage in long-lived materials and products. So I think it's important to also shed a bit of light on post-SR 1.5 insights here. And then somehow awkwardly in the middle we have this combined thing nobody really knows where to place backs in the title of the workshop it's called a hybrid technology. And this is actually also one of the reasons that many people are now proposing to actually have a typology that's based on where the CO2 actually ends up is it in the lithosphere, in the hydrosphere or in the biosphere, but I think this typology that's actually also used in emissions gap report by the UN will do just fine for our discussions here. As I said, I will only make a couple of general points and nature-based solutions since there was my title because they are actually quite powerful when it comes to climate protection and we've seen that also in the intro presentations and there was recently a comment out by Celine Girardin and colleagues that were really showing that nature-based solutions could actually reduce peak temperatures in 1.5 degree trajectories and also to a degree trajectories. And there is a lot of literature out there that supports that nature-based solutions especially also what Chris was emphasizing keeping our sinks intact or key for reaching the ambitious climate targets set in Paris. In addition, they enable pathways with some sort of cost containment. So we did some research where we also took nature-based options out and then we saw that this led to significantly higher carbon prices which leads you to ask then are these politically feasible anymore? And will that then actually lead to ambitious targets being abandoned? So that that's another advantage that nature-based solutions bring. They're not facing as much public opposition as some of the technological approaches. I can say that because I come from Europe especially in Germany, it's been very difficult to talk about geological storage. So anything that has to do with CCS and also they can be managed such as to exploit multiple co-benefits. And I'm sure that people also touch base in his presentation tomorrow. However, a word of caution also because I think in the debate some things are always thrown into one part and that's often not very useful when it comes to implementation. Nature-based solutions are actually much broader than natural climate solutions. They involve working with and enhancing nature so as to help address societal goals of which climate protection is one. But as you see in the graphic on the right-hand side there are many more. And often actually nature-based solutions have important benefits for society where carbon sequestration is more the co-benefit. And if you manage then nature-based solutions by only looking through your carbon lens you can actually come up with quite suboptimal outcomes. So a broader approach where carbon removal might not be maximized but many positive synergies can be realized might be more promising here. So after this word of caution on nature-based solutions let me go back to our usual suspects from the introduction I made. Here I show you the costs and the potentials for carbon removal of the different categories I've been showing you before. These are, this is a systematic literature review for 2050 costs and potentials. You see wide ranges. This is partially of what I've been mentioning before that you actually have a wide, these categories are a basket of individual technologies but it's also different assumptions that are standing behind the estimates. And what you see though is quite an impressive potential that each of those could be ramped up to with a word of caution again. The caveat is that these are mostly bottom-up studies so you cannot really add those up. So they're competing for the same resources mainly. For instance, a piece of land that you have just forested you cannot put a biomass plantation for becks just as a brief example. On cost you also see wide ranges direct air-con capturing storage will also in the middle of the century still be at the upper end of the spectrum with $300 per ton of CO2 looking quite optimistic against some of the applications and what they cost today. So this is not unrealistic. Becks is somewhere in the middle with enhanced weathering and then we see the options that are more on the natural side, aphoristation, soil carbon saturation biochar that are more on the low costs side of this spectrum. However, you see that they have these dashed lines around them these asterisks, aphoristation and soil carbon saturation and that's supposed to show that they are actually more reversible than the others. Wildfires were already mentioned in the Q&A box. CO2 can quickly be released both for anthropogenic and for natural reasons as we see ongoing climate change exacerbating some of these effects such as droughts and other disturbances. So this is something that we have to reckon with in a long-term strategy that some of these could be reversed and it's also of course a challenge for any governance and policy framework. So as you already feel, none of these really looks like a silver bullet. And what I personally believe is that we will be seeing a portfolio of these different options that will be diversified not only across technologies, but also across geographies. And I think it is very important to now conduct studies to see what fits in with context and I will be coming back to this point in a minute. Before I wanna show you from the 1.5 degree report the full range. So what we did in the systematic literature review is that we also elicited expert judgment on what are the assumptions behind the large ranges which were much larger in the literature and try to come up with something more realistic for the middle of the century. Also considering sustainability constraints and so on. But what you see here is actually the full range. I don't wanna go into detail with respect to all of the technologies here though. But I wanna draw your attention to the right-hand side of the graphic which is on the side effects. And this basically shows the state of knowledge of the side effects of the non-carbon effects that the large scale deployment of these options would have. And here this is another illustration of what I've been mentioning before that we won't see a silver bullet. All of those technologies I've been showing you will come to their limits. And with some of those you also see positive side effects for instance enhanced weathering could have a positive impact on crop yields if applied to agricultural areas. Same for biochar, some of the soil carbon techniques. But for instance, if you look at BEX most of the literature is really pessimistic. They look at these double digit gigaton removals in the AR5 scenarios. And then the concern is of course with that much land that you would need to grow the biomass you of course put biodiversity targets, food security and much else in jeopardy. So that doesn't mean that there can be positive impacts of BEX as well but at least in the literature these are not prevalent yet. I think though that it is time to step a little bit away from those global pathways and having this sort of discussion around oh, they're showing us 10, 20 gigaton CO2 removals with BEX and that can't work but what we've also already seen in Jim's portfolio of technologies. It's now time to see what works in which geographical context as well. So to illustrate that point I've brought you the Swedish case because in Sweden they actually have a number of large scale industrial applications all conveniently located at the coastline and most of these are actually biogenic in the emission sources. So retrofitting those with CCS achieves negative emissions without actually needing to dedicate any additional hectare of land for further biomass cultivation. So this is a typical example of what I have in mind when I say that we need now to see what makes sense in which context. Definitely we won't get to 20 gigaton CO2 removals through BEX in a very sustainable way globally but in some cases these things might make a difference and it's good to not exclude options ex ante when we look at what could work in which country. And this is the marginal abatement cost curve that comes forth from the Sweden case. The green bars are all the biogenic point sources the gray ones, the fossil ones and you see the green ones make up a substantial fraction of the total. And if you add them all up it's actually more than half of the total Swedish emissions. So from all sectors that will be offset here. So just one plea to actually go forth with the work at national level as well. Now I promise to also say something on post SR 1.5 work and one big debate that we're having in Europe as well and we're having here as well as we saw it was a quite prominent solution in Jim's pathways is CO2 utilization. And that's not a wonder because it's actually a quite attractive narrative we don't consider CO2 anymore as a waste product but it's a resource, it's a raw material that we need and that we use and it gives us a notion of a circular economy. We could have potentially a big reduction of net costs of emission reductions maybe even removals if CO2 gets stored in a product. We could potentially have a big learning effect for other CCS technologies and in the end we would be using a cheaper and cleaner feedstock than the conventional hydrocarbons. So there's a lot of optimism in this narrative and we conducted a systematic literature review after SR 1.5 with colleagues from Oxford where we looked at a couple of those different CO2 utilization pathways and we actually did find that for 2050 there's quite some utilization potential and what you see here is a speculative CO2 utilization curve I call it where you actually see the potentials plotted against the breakeven costs. That means that in 2050 if you see negative breakeven costs these are processes that will be already commercially attractive on their own whereas those with positive breakeven costs they would still need some support to be economically viable. And we've looked at a lot of different things that would already make sense in the middle of the century. I mean, Pauliol and Yuria we already see that today but also enhanced oil recovery is something that's already being practiced. Others such as processes in cement curing fish and trout fuels would still need support in 2050. However, what I'm showing you here is a utilization curve. It's not a marginal-bakeman cost curve and that is very important when we discuss CO2 utilization as a removal option because CO2 utilization could be doing a lot of things and where those circles of carbon dioxide removal, carbon capturing utilization and carbon capturing storage intersect these are actually very small areas that could really lead to removal in the end. CO2 utilization could even increase CO2 emissions. If you, for instance, use a lot of non-decarbonized energy to, for instance, make synthetic fuels or you could have no net impact on CO2 but increase other greenhouse gas emissions, potentially synthetic fertilizers or you could reduce CO2 emissions but not remove CO2 from the atmosphere on a net basis. So there were a couple of questions already in the chat about this. Where does the CO2 actually come from? What is the timeframe when the CO2 is released again from using the product? And then, of course, you still have that smaller intersection back-related chains, for instance, where you would really have a removal of CO2 from the atmosphere. So in this whole debate around scaling up CO2 utilization for a removal strategy, I think it's really important to keep in mind not to support CO2 utilization per se but to really look at what emission gets avoided or even removed. And for that, I think three things are important. Where does the CO2 come from? Is it a biogenic source? Do we have it from the atmosphere or have we actually captured it from fossil sources? What is the system that we're working in? Is this decarbonized? The energy that we use to transform the CO2 into the product. And then finally, what kind of product do we actually substitute for and do we release the CO2 upon utilization of the product? So with that caveat, I wanna go to something else that we haven't talked much about but that Rob actually mentioned and these are non-CO2 greenhouse gases. I'm not gonna say much about that because CO2 is the focus of this workshop but global methane emissions have been on the rise more than 60% coming from anthropogenic sources. You've seen what Rob was showing from the global carbon project, the methane budget and actually reducing methane from agriculture and also fossil fuel extraction to zero in a short time, that's very unlikely. In addition, we also have to grapple with earth system feedbacks. So a future scenario where you have an accelerated methane release from permafrost is very well possible. So it may very well be the case that we have to remove methane but in a paper that Rob has forthcoming very soon that's already accepted. He shows that many knowledge gaps remain. I'm not going into the different methods for removing CO2, we can pick that up in the discussion but what that paper clearly shows is that we need a research agenda costs, technological efficiency, scaling, energy requirements but also in the social barriers, co-benefits, byproducts and more broadly on methane surption to concentrate methane from low concentration background air which is also something to be discussed in the frame of direct air capture, of course. Now finally, I want to make a point about innovation. I've seen that there were a couple of questions in the Q&A box sort of pointing in that direction. Who is going to pay for this? How can we actually do this quickly? And I know on day three, we'll dive more deeply into this and my colleague Greg Nemet will be talking about this. So I borrowed an illustration here from him to sort of set the ground for this discussion as well where there's a comparison between another scaling example in the climate change mitigation debate solar PV where you had the first commercial application in 1957 and then only recently we really talk about low cost and then we're still a couple of years away from being really in a position to talk about widespread adoption. Now, if we would translate that one to one as a sort of back of envelope calculation on direct air capture with the first commercial deployment of climate works in 2017, then we would be at low cost some time in the middle of the second half of the century and that widespread adoption at the end of the century when we would have long needed to achieve large scale deployment. If we think back about the global pathways I was showing you in the beginning. So it seems that the standard traditional innovation models that we've been using do not work for the technologies that we're talking about here and that we need new models that can accelerate the development bring us to low cost already in the first half of the century and to widespread adoption earlier in the second half of the century. If we are already talking about the global pathways that I've been showing you in the beginning then what's also striking is the large innovation gap that we see. We actually see these things being scaled up as of 2020 but in reality, we don't see a lot of this on the ground yet. We have an increasing knowledge base on CDR approaches. We know more about removal potentials, cost side effects, systems integration even but then when it comes to innovation, public perception and policy, there's really a big hole in the knowledge. And this is what also came out of the systematic literature review. We tacked them, all the papers we found for their innovation stage and there's a lot of research on research and development and scale up very little on niche markets, demand for public acceptance all the knowledge that we would need right now in order to set us on the right pathway and scale up. So with that, I wanna come to a close. There are a couple of takeaways I wanna leave for the discussion. Greenhouse gas removal, I turned during the presentation from carbon dioxide removal to greenhouse gas removal as I mentioned methane as well is really a rapidly evolving field that's an expanding set of technologies and practices that we're talking about here. None of the approaches is really a silver bullet. We'll need a portfolio of options. We need actually a societal discourse on how much we want to remove and how we want to do that. And we'll need to close a huge innovation gap quite rapidly and expand also our knowledge for doing so. So with that, thank you very much for your attention and I'm looking forward to clarifications questions and even more so to the discussion later on. Great, thank you Sabine. That was excellent. We do have a couple of questions that have come in. The first one is from Shafiq Jaffer. And this question considers national versus global level. So how should we consider investment costs and the benefits to reach national net zero versus international? How should we think about dollars invested versus tons of carbon mitigated to avoid the suboptimal use of limited capital? Yes, this opens the big box also of emissions transfers and that we could have cheaper potentials to be wrapped elsewhere. And I think that is also something that's coming forth quite strongly from the literature. If we look at scenarios that limit the amount of emissions transfers that are possible, it becomes more difficult definitely. It becomes more costly. But the problem then is that this is not the complete answer but when we move to implementation, there are of course certain risks involved in sort of reaping those cheaper mitigation potentials. And these have to do with how these emissions transfers are really governed. How is it measured? Do we have the monitoring systems in order to really measure whether a ton was really removed? Are they permanent? Who's liable for the permanence of these things? How can we prove that the projects are generally removing it? How can we actually avoid some of the things that Jim was already alluding to, which revolve around are these substituting more expensive decarbonization that has to happen anyway as well? So are we talking about actually causing some sort of delay in emissions reductions that would otherwise happen? So in principle, yes. There are reasons to say that capital could should be directed also at opportunities that we have transpound voluntarily. But this has to be happening with caution and with the right governance in place. Great, one more question. Can you talk a little bit more about the ancillary benefits of nature-based solutions and what different parts of the world are doing with respect to implementation? And this question is from Jennifer Mow. Yes, so the thing is that nature-based solutions are so broad and sometimes they don't even have anything to do with the objective to save the climate in the first place. So in that sense, there is already a lot going on. The problem with the ancillary benefits and how to sort of bring them together with the climate protection agenda is that for many of them, it's also difficult to measure them. And you saw I had for the side effects also the positive ones, these little icons in the IPCC report and that was actually born out of the frustration that you had very little material quantifying some of these things. And that will make it very difficult to get payment systems going that sort of can account for a broader portfolio of values or ancillary benefits. Having said that, there is actually, I mean more and more investors, also institutional investors face the challenge of speaking to more than just carbon. Also the Green Climate Fund, even though it's a climate fund, has safeguards and criteria for non-carbon benefits. So I think we are on the way to sort of integrate that. And I think also if we have the carbon lens on, we can work with governance and regulation so as to ensure that hotspot areas are protected and that we actually avoid risks. I mean, even if we can't measure things and put it all into monetary terms, it's of course possible to identify areas that warrant protection.