 I'm pleased to now introduce our next speaker Rob Jackson. Rob is the Michelle and Kevin Douglas Professor in Earth System Science at Stanford, and the title of his talk is Global Carbon Cycle, Syncs, Sources, and Carbon Budget. Hello everyone. It's nice to be here. Thanks for the organizers and thank you all for participating. It's been great so far. So I'm here to talk about Global Carbon Cycle, Syncs, Sources, and the Carbon Budget. Chris gave you some snippets of that in his talk, and we'll hear a lot more about ocean carbon cycling in Paul's talk directly after mine. So I'm here as the Professor of Earth System Science at Stanford, and I also chair the Global Carbon Project, which I'll mention next. All right. So the Global Carbon Project is an international organization of hundreds of scientists. Some of you are on the call, as I've noticed in the participant list, and we produce greenhouse gas budgets for the dominant three gases, carbon dioxide yearly, now led by Pierre Friedlingstein. Methane, we just released our Global Methane Budget, led by Marielle Sunois in Paris just a month or two ago. And for the first time, I'll talk about it in a second, a Global Nitrous Oxide Budget, led by Hunching Tian in Auburn and Rona Thompson in Norway. The Global Carbon Project makes all the data that we collect publicly available, and we try to be as transparent as possible. And we have additional priorities for GCP that include cumulative emissions, the kinds of sort of bucket filling that both Chris and Sally talked about. How much emissions do we have left for a given scenario, and temperature threshold, and how much confidence do we have in that? We work on negative emissions and also urban systems. So I mentioned that we just released our Global Methane Budget a couple of months ago, and this isn't a session about methane, but I think it's important to remember that there are other greenhouse gases that are important in the mix. And the methane cycle globally is far more perturbed in terms of the percentage of emissions coming from human activities than the carbon dioxide budget is. So today, about 60% of global methane emissions are coming from things that we do, roughly two-thirds of those coming from agricultural activities and one-third from fossil fuel use. And there is starting to be an emerging negative emissions research agenda for methane, something I work on personally, and some others obviously do as well. So that's much more nascent than carbon storage for carbon dioxide. The global nitrous oxide budget is dominated by agricultural emissions, almost exclusively some industrial emissions, and I won't talk about the specifics of that so much because the work's still in press. But we have our work cut out on all three of these gases. So in none of these gases, CO2, methane, or nitrous oxide, are we anywhere close to a 1.5-degree stabilization? And really are closer to three degrees, or even pushing four degrees in some cases, rather than one and a half or two. So let's switch to focus in on the carbon cycle then, which was the mandate for our session today. The global carbon budget that we just released led by Pierre in December, this is a sort of a 60-year timescale of global CO2 emissions. You see steady increase, emissions in 2019 were an estimated about 36.7 billion tons of carbon dioxide, fossil fuel activities, and cement production. You see a couple of things on this graph, the increase has slowed down somewhat. In recent years, at least over the last decade, the rise, the increase in emissions has been about 1%, rather than the 3%, or so that it was in the first decade of the 2000s. And with some hints of stabilization in single years, perhaps, but really no hint of turning the corner of stabilizing CO2 emissions or even having them trend downwards. And of course, as you've already heard from both speakers, it isn't enough to stabilize emissions. If we stabilize them today, it would be at record emissions. What we need to do is get them close to zero, or net zero, using other approaches. So we have a long way to go. Another interesting thing you see in this graph is how little influence economic downturns and such have on the long-term carbon balance. You see just sort of little sawtooth for a year or two around the great recession from a decade ago, or the fall of the Soviet Union combined with a savings alone crisis reduced emissions a few percent just for a year or two. So it's really about decarbonizing the energy sector. All right, well, why are carbon emissions still rising? Despite really rapid and amazing renewables growth of 14% a year over the last five years. And Sally touched on this. It's really because global energy use keeps increasing. And so most of the renewable infrastructure that we're building isn't replacing fossil fuels. It's adding new energy and meeting new energy demand in the system. And there is one key area where renewables are replacing fossils. And that's in the electricity sector in Europe, here in the United States, where renewables and natural gas even more so are replacing coal. So coal use, coal consumption has been about flat for the last five years or so. But it's going up in other places, India and China still coming down in some of the places that I've mentioned already. But this is why we can have really rapid renewables growth and still have natural gas increasing at two and a half percent a year over the last five years and unsustainable amounts. When most of that natural gas isn't offsetting coal, it's meeting new energy demand. And of course petroleum use is still rising too. So we have this balance where basically energy demand is rising so quickly that the increase in renewables isn't offsetting primarily fossils. So we can look next then at how not to cut emissions. This was a paper that we published just a couple of months ago led by Corinne McCarray in the UK. And this is an effect of the COVID lockdowns. We've got so many questions about what are the lockdowns? What is the virus doing to carbon dioxide emissions? And we estimated these on a daily basis. So you see the same sort of 50-60 year graph on the left. And then that red sawtooth is what we observed this year. So we looked at different levels of confinement in different countries. And then we mapped on various sectors of the economy, transportation, which declined the most, industrial activity, steel production was down, power and other things. So our estimate that was in early April at the peak of global confinement, global CO2 emissions were down by about 1.6, 17 percent. And emissions in single countries like the US were down almost a third for sort of a week or so in that same period. So we had really dramatic declines. We estimate somewhere between about a four to seven percent annual decline for this year in fossil CO2 emissions. And that may not sound like very much to some people, but that will be the biggest decline certainly since World War II and probably ever. But of course, the trick here is that this isn't a sustainable way to reduce emissions. We can't decrease emissions and meet our climate goals by having hundreds of millions of people out of work and having everybody staying at home. So that's sort of the challenge that we face. All right. So Chris showed this briefly. This is a bit of an update on the version that he showed, but sources on the left of CO2 emissions and sinks, where that carbon dioxide goes on the right. And about 35 billion tons of carbon dioxide a year, that's average for the last decade, 2009 to 2018. So the lower than we saw last year, 36.7. And about five to six billion tons of carbon dioxide arising from deforestation and other practices. And then the fate of that carbon is to less than half of it stays in the atmosphere. That's about the 45 percent or so figure on the upper right. About 30 percent of it is going back into land. And this is partly from carbon dioxide fertilization, other effects as well. And 20 to 20 percent to a quarter of it's going into the oceans in a given year. And Paul will talk about this in a lot more detail in the coming talk. So you see that really we're getting in a sense a free ride. About half of the emissions that we release are not staying in the atmosphere. They're going into land and into the oceans. Well, let's look at land use change emissions over the past 60 years or so. And you can see that they've been, you know, they were decreasing for some time, especially sort of the 60s to the 80s. And they bounce around given year, but they've been sort of steadily but slowly increasing back upwards to five pushing six billion tons a year. And I think many people know that this year in particular, Amazon deforestation, for instance, has increased one third compared to 2019. So there's a lot of concern as we discuss nature-based solutions today that with some pressures of economic activity, national policies in countries like Brazil, people being out of work, that we may go backwards in some places because of the need to use land in the short term for economic gain. So anyway, the deforestation and land emissions are kind of creeping back upwards. And that's, and that's something of concern in the mix too. When we look at the, at the overall, overall picture, again, on a 60-year timeframe, I believe Prussia, this slide, you see land use that we just observed on the bottom there in billions of tons, five or six. And it's really now today about fossil carbon dioxide emissions, you know, pushing, you know, in the high 30s. So we're about, you know, about one seventh of total emissions are from land, but really the story is fossil carbon emissions. And that's why, you know, an appropriate focus on sort of low-cost nature-based solutions is timely right now, but the real work will come in decarbonizing the energy sector, as Sally discussed. All right. Well, Paul will discuss the ocean sink, and I'm not an ocean scientist, but you know, we are gaining a benefit in terms of the atmospheric balance for carbon dioxide from the CO2 that's absorbed in the oceans. And that is about nine to 10 billion tons of carbon dioxide a year, about 9.6 in 2018, as an estimate from different ocean models. So we really can't ignore the importance of the oceans. And this is, you know, primarily a physical process with carbon dioxide dissolving. The biological processes are really important, too. And Paul will discuss this in much greater detail in the next talk. Then when we put these pieces together, you see a picture that looks like this then. So sources are above the zero line, sinks are below the zero line. Again, in this case, going back about 150 years, a century and a half, the gray is fossil carbon, and you see the dominant source today, land use change in that sort of orange color. And then below the zero line is where that is the fate of that carbon. So there's the ocean sink in blue, the land sink in green, and then what's left over is what we see is going up in the atmosphere in that light blue along the bottom. And we do also in the global carbon project estimate an uncertainty now around these, and that's about 2 billion tons of carbon dioxide a year, which is pointed to with that gray hatching. So we don't know these terms with perfect certainty, but things like the atmospheric increase and such, we do know quite closely. So one thing you'll notice here is the variation in the land sink. And I think that's really important to point out in the context of nature-based carbon solutions. The land sink varies a lot. The emissions on the upper right there vary somewhat, but the land sink is a lot more variable. And we're seeing aspects of that right now. Some years we have record fires. And we may, you know, these are, we're seeing sort of a couple of the biggest fires we ever had in California. Australia just went through an incredible unprecedented fire cycle. But things like the Indonesian peat fires 20 years ago associated with El Nino activity had a far bigger effect. But it isn't just about fires, it's about wet years and dry years. How much sort of semi-arid systems absorb in a given year if there's a little bit of extra moisture in the system. So that kind of variation leads to the sawtooth and variable picture that you're seeing here. And I guess gives us a hint that there are perhaps things we can do or at least there are changes that are happening on the earth that allow natural sinks on land to be manipulated. Of course, we don't manipulate things at a global scale in terms of land at least yet. All right. Well, let me spend my remaining time just on a few slides about natural climate solutions then. And as we already heard from Chris, a good question from Laurie, when natural climate solutions do certainly have an important role to play. They are the cheapest form and really the most readily available. We have to constrain those or acknowledge that we need land for other things, food and fiber production, biodiversity conservation, water quality and provisioning and many things. But this was the Griscum et al paper that here's a figure of emissions historically for global carbon dioxide. Business as usual is that dark line heading upwards. Fossil fuel mitigation is the large triangle in gray. And the green really is the kind of natural carbon solution mitigation that Chris referred to. And this could be a billion tons a year up to five and some people have proposed even 10 gigatons of CO2 a year. So anywhere from about five or 10% of CO2 emissions to even a quarter of current emissions, although that number is quite high in my opinion. But the key part of this is that they in their estimate show or at least estimate that these sinks are available at less than $100 a ton of carbon dioxide, which is really in future scenarios quite low. But what are some options for us? And I think it's important to acknowledge management and how many opportunities there are. I mean the number one thing that we can do is to reduce emissions from deforestation and degradation. That is not a new idea. Goes back to red to red plus. And of course, as we've just seen deforestation and other land use factors contribute five or six billion tons of carbon dioxide a year. So anything we can do to save that carbon, to keep it in place, to put it back will be a tremendous benefit for us and for the atmosphere. And it isn't just about carbon dioxide emissions. I think it's really important when we discuss these solutions to bring in a suite of other co-benefits that are likely to occur. And there are a lot of those co-benefits in some of these forestry activities. Trees help us produce erosion by preserving tropical forests and forests elsewhere we enhance biodiversity. We reinforce the sort of tropical convection, water recycling and cooling benefits that we get. So there are many, many reasons to support these forest activities beyond putting carbon back into the land or retaining that carbon. Another initiative that you've probably heard about is the bond challenge, which attempts to restore 150 million acres of deforested land by essentially this year. That's about 350, 400 million acres of 150 million hectares. And then of course by 2030, the bond challenge is even more ambitious about 350 million hectares or closer to 800 million acres of land. And that really is a lot. So if we could meet those challenges, we can't address climate overall, but we can put a dent into it. And it's that suite of all hands on deck, all approaches are needed that I think is important for us to remember. Natural carbon solutions are part of that mix certainly. You've all heard about the Trillion Trees Initiative and we can restore millions of acres of forests, store billions of tons of carbon on land enhanced by diversity and ecosystem services. And I think we haven't really talked very much about engaging and inspiring the public, but this is another place that natural carbon solutions done well can help us. People relate to forest restoration. They understand the importance of nature, the aesthetic, the personal and mental health benefits that being around nature provide for us. And so this this aspect of engaging in public I think is really, really important to remember. And we also of course need public support for these activities. Not all natural carbon solutions will be cited with a magic wand. We need people both public landowners and private landowners to implement policies. So we need the public and I think these approaches can can help us do that. Well let's go on and I want to spend just a few more a few minutes talking about some things that I am concerned about with natural carbon solutions. Not to the point that we shouldn't be doing them, but just that we should be thoughtful about doing them. Something that we've worked on in our group a lot is is water issues and the fact that you can't manage the world for carbon without altering water and the energy balance. And this is work that goes back you know many, many decades from researchers in Australia, South Africa, places where where water has been a concern for a long time. This is a figure in on the right in the change in annual runoff in millimeters. Each of these dots is a stream or a gauge stream over the course of one year. The zero line is there in black. And the x-axis are plantations. So the age of plantations that were established in a four station on previous grasslands, shrublands and such, essentially putting trees where they weren't. And you see that in a picture I took in Argentina on the left, those are pine plantations in native grasslands. And what we see in the summary figure is that almost universally a four station putting trees where they don't typically or haven't typically grown reduces stream flow substantially. In the course of about one out of eight streams, the streams dry up not temporarily for the entire year. So we need to be careful and think about managing water and also thinking about managing albedo and the energy balance. Trees are darker than than many of the systems that they cover. And so they can increase warming locally while providing a climate benefit globally. So being thoughtful about these these concerns and not having carbon blinders on is something that's important for me. I want to just point to a couple of papers that have come out. This was a nice workshop summary that Bill Anderug and some of us published earlier this year. And it's acknowledging the risks with natural carbon solutions that come from disturbances, climate change, and we can't ignore human behavior. The decisions that we make about whether to cut a forest, we want to cut a forest, how to manage, you know, extend the length of a rotation and different things, especially on privately held land and call us our Pokemon slide. But we have, you know, science tools that can can help us monitor these situations with remote sensing now models, monitoring plots and such. But then everything on the right, the policy from governments to private landowners to NGOs and companies, of course, influence the potential for forest and natural carbon solutions. And these include soils as well. So we have to think about disturbances and other factors as we move forward in permanence and keeping the carbon in the landscape that's there and keeping carbon that we place in the landscape there over decades to a century. This was a second paper, this one led by Nate McDowell. And here we focus a little bit more on on disturbances and how they appear to be accelerating, including fires in some places. You know, globally fires aren't increasing. Many places they're decreasing because of less human set fires. But in Western North America and some other places they're definitely becoming more common as we're seeing here in California. But it isn't just about fires, it's droughts, large scale droughts, insect outbreaks and more. And globally, forests are getting younger, not older because of human management coupled with these disturbances. So if we think about a trajectory like in this cartoon that you're seeing here, we have sort of an older forest originally that forest is disturbed, whether the disturbance be from a human management or decision or from, you know, some natural source, then that recovers. And what is an old forest is becoming younger in a sense because we're turning land over more. So there's a trade-off, a balance if you will, between keeping carbon on the land as you have on the left and perhaps using carbon for a bex or a biomass type situation that we also haven't really talked about much and you might cover in the Q&A. So that's a second paper I wanted to mention. Pete Smith led a paper for us some years ago on the potential for negative emission scenarios. And I just want to remind people of the scale that we're talking about. Now, 10 billion tons of carbon dioxide a year is a lot. That would be a quarter, essentially, of fossil fuel emissions today. You know, the numbers that you heard earlier were 1 to 5 billion tons of CO2. But at that 10 gigaton scale, you know, the acreage that we estimated in this paper required to meet those demands is a billion, you know, close to 2 billion acres, roughly one half of current acreage today in agriculture. And we're not going to convert cornfields in Iowa to these carbon storage activities. They'll come from more marginal lands and lands that we use for other things. Everything from biodiversity to recreation to grazing and such. So, you know, when you start thinking about another half a billion billion acres put just to managing the carbon cycle, that's a lot of land. And there will be other things and endangered species and other needs and desires for that land. So it isn't going to be easy, especially as we push the limits for the maximum biomass to store on land. And then here is a kind of a closing slide. This is a paper, I believe Sabine Foust is on the call. Also a GCP member, she led a paper that came out a month or two ago on negative emissions. And this is a kind of a simplified figure, if you will, the upper right, is what happens if we decarbonize very quickly. You know, the green slice of the pie is much smaller, of course, than what you see in the bigger panel in the lower left. So the longer we go and without mitigating and really turning the corner on emissions, and the longer we take to get close to zero, the greater the size of that green wedge needs to be, and the more expensive it will be. And the more vulnerable vulnerabilities we have associated with those activities will be. So I'll point to that. And I guess I'll stop there. I have an animation that I would show if I can share my screen, but it's not necessary. And I'm happy to take questions. So thanks for your time. Thank you, Rob. That was wonderful. Definitely lost to think about. I'll hand it over to Jenny to start the Q&A. Yeah, thank you, Rob. Very thought-provoking. So I'd like to go to Shafiq. He has a couple of interesting questions for you. Shafiq, would you like to ask your questions? Thanks, Jenny. Rob, my question center a little bit on the economics here. One is when we look at land use change due to kind of the economic drivers for a lot of the developing countries, especially, do we have an idea of what sort of incomes are being generated per hectare that is being deforested? I mean, what is it driving that from a monetary standpoint? Well, the incomes, and I should have the numbers of my fingertips, I don't. But when you look at the income, say, and let's take the biggest example today, or the poster example of Brazilian deforestation, the incomes that arise from deforesting the Amazon and planting soybean or even raising cattle on that land far outweigh right now the any economic benefits that governments or private landowners receive for carbon credits. So that's really one of the challenges. And I think we haven't talked enough about pricing. I think that's the heart of your question. And we've had a few nods to it in the various talks. But the carbon price that's available today is nowhere near what we need to reach billion ton scales. There are low cost, natural based solutions available right now in the sort of five to 10 to $25 ton scale. And there's really no other bucket, I think, no other technology available at scale for that. But those low cost ones are relatively, relatively small. We should use them quickly. But we're not going to get to these billion and gigaton scales unless the carbon price is substantially higher than it is today. And the integrated assessment models show that very clearly. They have hundreds of dollars a ton carbon dioxide pricing later in the century. Without that, none of these activities will happen unless there's some sort of government mandate. And quickly on the bond challenge, which was interesting is to say, okay, what does that cost look like for that many trees? And how much carbon would that mitigate? I mean, is there any kind of numbers being put against that challenge? I'm sure that there are. And there may be, there are some integrated assessment models on the session, and I'm happy to have one of them contribute. Most of the estimated cost for these large 10 to 100 gigaton scale negative emission scenarios are coming from these integrated assessment models. And I don't know what the estimate for the bond challenge would be. But again, when we really look out past 2050, when that green wedge for negative emissions is large in that last slide I showed you, those prices are hundreds to $500 a ton CO2. And we're talking about trillions of dollars. I think for me, this really highlights something Chris said, that the longer we wait, and we sort of wave this magic wand, it's not a magic wand alone. We can do some of these things. But it is going to be much, much more expensive to do them in the future at hundreds of dollars a ton than keeping that carbon and those greenhouse gases from reaching the atmosphere today. And I think we can't lose sight of that. And it isn't in either or situation, as we've discussed, it's both. But mitigation now has to be the primary focus while we do these other things that are also very important. Thank you. Thank you. We think we have time for a question from Ajay. Ajay, would you like to ask a question? Do you want to meet yourself? Yes. Thanks, Jenny. And thanks, Rob. Just picking up on actually a last remark, because both you and Chris mentioned that NCS should not be thought of, has kind of some sort of magic solution or an answer, and we don't do anything else. So business as usual is, of course, not an acceptable answer. But when you talk about the disturbance outside, Rob, could you comment a little bit more on, do you think that by highlighting the fact that there could be other issues that prevent us from getting the benefits that we believe we can get, that we would even not go after NCS in the near term, because there are some significant low-hanging fruits to be had, even as the globe starts figuring about how to kind of make that turn on the overall trajectory. So could you just comment on that, Rob? If I interpret your question correctly, and it's a really important one, I do feel strongly that we should be going after natural carbon solutions today. And I think I highlighted a couple of those situations, the reforestation, avoiding deforestation, kind of the whole restoration idea of putting things back, especially where they were, I think has a lot of advantages. And we need all of these things. It isn't an either or. So there are issues with permanence, though, as we think about, especially in those large estimates in the Bastinen outpapers, we sort of think about stuffing carbon everywhere and as much as possible. I think that's a dangerous path to take. Carbon doesn't necessarily belong there, whatever that means. It's going to be more vulnerable. So I think we need to use and push these nature-based solutions. But as Chris said, they are a replacement for fossil fuel mitigation. There are important supplements to it.