 The task that Arun and others asked me to talk about, and I really want to build on what you've already heard about, Arun's discussed energy. You know, Chris gave you a really nice overview of climate and where we are. And so I'm not going to talk about climate, but they asked me to speak a bit about emissions trajectory, sort of where are we in different greenhouse gas budgets, and how do we know? So I'll talk a bit about carbon dioxide, a bit about methane, as Chris mentioned, and talk a little bit about solutions and give you some examples from our work as well. First, just to build on the climate components, I guess if you remember one thing from my talk today, it's to get involved early. And I'm going to suggest that you find a professor or some topics that interest you and reach out to those professors as soon as you can in your stay. And you have a lot to contribute. We need your input. And I think we have some things to provide for you that can help you learn and increase your skill set while you're here at Stanford too. So this is an initiative that we started this year, and we're doing computer science is really the computer science brains behind this. But it's an artificial intelligence bootcamp for climate, where we work with undergraduates, graduate students, and postdocs, kind of linking the computer sciences up with the earth sciences and other areas, energy, engineering, and such. So this is an example of the kind of thing that goes on here at Stanford. This is a concentrated semester where the undergraduates spend 30 or 40 hours a week working on scientific questions that we put forth. One of them is a global analysis of methane emissions that I'm helping to organize, and that's just one example. So get involved. That's the one thing I want you to remember. OK, the Global Carbon Project. Briefly, well, who are we? What do we do? We're a group of hundreds of scientists, and we publish for carbon dioxide an annual budget of sources and sinks for carbon dioxide from natural sources, because you have to understand the natural system to understand the perturbation to that system through human activity. So we study ocean carbon cycling, land-based carbon cycling, like Chris mentioned, forest, grassland, soils, industrial activity for power plants, vehicles, methane emissions from heating our homes, and pipelines that leak, and things like that. So we put these things together into budgets that combine top-down approaches, satellites, aircraft, tall towers with bottom-up approaches, inventories, chamber-based measurements, accounting valves, and pieces of infrastructure and estimating things this way. And then ask, where do they match? And that's where the basic philosophy is to try and approach these budgets from two directions and see where, if any, discrepancies there are. So we do that for carbon dioxide yearly. Methane, we've just submitted our new methane budget this month. We'll have our first ever nitrous oxide budget out late this year or early next year. And then we work on some other things, urban emissions, and then the broad space of cumulative emissions and negative emissions. So how big is the atmospheric budget for greenhouse gases? When we talk about stabilizing the Earth's temperature at 2 degrees C or 1.5 or 2 and 1 half, how big is that bucket? How much space do we have left? And for those of you who are socially inclined, who gets to fill the rest of the bucket? And based on what criteria, per capita emissions, historical emissions, issues of equity, social justice, historical factors, things like that. So we work more on the physics, the chemistry, the Earth sciences of those budgets, but we're very, very interested in helping people use this information to make ethical decisions. So we'll talk a little bit about cumulative emissions as well. So here's where we are from. So we've released this at the last COP, the conference of the parties. In December, we'll release our next budget in Santiago in the current COP in December. So last year, 2018, we had about 37 billion tons of carbon dioxide from fossil fuel emissions and cement production. We had about another 4 or 5 billion tons from deforestation. So for carbon dioxide alone, the annual budget is now over 40 billion tons a year. I think Chris presented a cumulative budget for you that suggested we got about 500 billion tons of carbon dioxide emissions left to stabilize with for two degrees C. So you don't have to have a PhD in math to know that's 10, 12 years at current rates. Now there's some wiggle room in that. Depends how confident you want to be. If you want to be 90% certain, you'll stay below the budget. The budget's got to be a little bit lower. The bathtub's a little lower. If you're willing to take a little more risk, the bathtub's a little bit bigger. But anyway, we are not, as yet, decreasing global carbon dioxide emissions. And I want to talk about why that is. There are signs of progress. Like 2014 to 2016 was the first period in time when emissions stabilized and the global economy grew. And that's really, really quite important because in the past the only time emissions have dropped is when there's been global economic downturn. So we're seeing hints of progress, but they're not fast enough. Let me move ahead. These are current emissions now by year, 1960 to 2018 billion tons of carbon dioxide. India here, growing rapidly. Europe, US, China, and then the rest of the world combined. So you see, 20, 30 years ago, the European Union and the US were equivalent in terms of CO2 reductions. Europe has made more progress than we have in reducing our emissions. India's growing rapidly. Their per capita emissions are still four or five times less than ours in the United States. You've got 300 million people in India who don't have access to reliable electricity. Those people, for first and foremost, interest need more energy, not less. So we need to provide it to them like Arun talked about. And then China was responsible for much of the growth in sort of the 2000 decades. And now their per capita emissions are about the same as Europe's, but still only about half of ours. All right, so we've got declining emissions modestly in the US, even more so in Europe, but not anywhere close enough to make up for the other people around the world who still use less energy than we do. So where do these emissions go? On the left are the sources, about 90%, close to 90% of the imbalance in the global carbon cycle comes from fossil fuel emissions, about 10, 12% from deforestation and land use. And then only about half that carbon dioxide stays in the atmosphere. The rest of it's going back into oceans or back into land, regrowing forests, stimulation effects, fertilization and things like that. So really the atmospheric concentration could be rising twice as fast as it is for the same level of emissions. So one thing we study in my group, along with kinds of energy things I'll talk about today, is to what extent will forests continue to provide this benefit? Because if you sort of dial down or if that benefit slows, then atmospheric concentrations will rise for the same level of emissions. So that's kind of an example of a biological feedback with the energy system, that the kinds of things that people here at Stanford and elsewhere work on. All right, so we spent a lot of time thinking, where does the carbon come from? Where does it go? And how much of it stays in the atmosphere? Okay, so the good news, renewables are exploding. And you've already heard about this a little bit. So here's 14% growth for the last five years or so. All right, driven by technology, driven increasingly in the US simply by price, two and a half cents a kilowatt hour wholesale prices. So that's fantastic, the biggest sign of hope. Energy efficiency increases, the greatest benefit we've had for reducing emissions. But what else is happening at the same time? Look at natural gas use, look at oil use, a little bit of a decrease in coal, coal use and coal production. So at the same time, we're adding renewables at record levels, fossil fuels are still going up. All right, so some of that, some of this and some of this is replacing some of this. But that's not all that's going on. Primarily what's going on is that global energy use is increasing. So here's a graph of gross domestic product, a gross world product at the top going back to 1990. You see that that has risen faster than CO2 emissions or energy. So our global economy is becoming more efficient. That's good. What's not happening, and maybe the biggest surprise to me when I see a figure like this, look at 1990, look at the CO2 emissions per unit of energy. They are the same today as they were almost 30 years ago, right? So that means that for all this progress, and I'm serious, this is a fantastic progress in renewables, we're still sort of building fossil fuel infrastructure and emitting that fossil fuel infrastructure sort of in the same proportion. So on average, globally, we're not taking fossil fuel plants offline when we produce a new windmill or a new solar farm. We're adding it to our energy infrastructure. So we need to think about how to take those facilities offline. Ideally, as Chris said, not in a way that takes power plants out of the cycle before their lifetimes are up, we need to figure out ways to decarbonize our transportation sector, which is more different than electricity. But this is fundamentally what's changing, and because that's not changing, and energy use is still going up, emissions are still rising. And now there are different ways, let's think a little bit now about trajectories, different ways to think about how we might stabilize at one and a half or two degrees C. And these are just very much cartoonish, Glenn Peters from Norway, Cicero in the GCP put this together a few years ago. You could imagine, all right, we're gonna wuster along at 40 billion tons a year, and then whammo, we're just gonna stop emitting carbon dioxide completely. And you get this sort of scenario at the top. Or you can say, let's take a really aggressive mitigation scenario, three, four billion tons a year, scale that back down, keep within our budget, or since we don't appear to be willing to do either of those things, maybe we reduce emissions, go beyond what that budget for one and a half or two C would allow, and then we invoke voodoo or technology, or both, to remove that carbon dioxide out of the atmosphere. And it's not strictly voodoo, there are technologies underway that might potentially allow us to do this, using trees, using industrial processes. I'll just talk about them briefly. But this is gonna be expensive, all right? This is like a drop of ink. You know, you keep the emissions from going into the atmosphere. It's like blotting a drop of ink. You let that ink go into a bucket of water, and you have to pull that ink back out of that water. You're gonna do a lot more work to extract that ink from a bucket of water than from catching it on your handkerchief. All right, so that's what we're facing if we wait for this kind of scenario. Well, what can we do? There are different approaches. So here's a typical fossil fuel plant results in carbon dioxide or carbon being removed from the ground, mined, burned, released to the atmosphere. We could make that carbon neutral by capturing the carbon dioxide, putting it back underground. We can also make it carbon neutral by using plants as the energy source instead of a fossil fuel source, burning that, and then that goes back into the plants. All right, but the only way to go negative is to say, for instance, use plants to take the carbon dioxide out of the air, burn them or use them for energy, and then pump that carbon dioxide underground. So in that sense, you're actually going negative from there to there, or to use an industrial process to go from atmospheric carbon dioxide to a plant to underground. So that's sort of the world of negative emissions. There's a lot of work that's being done in that area too. Just to give you an example, and I'll move on to methane, is a somewhat complicated figure, but these are examples of different negative emissions technologies. So biomass energy with carbon capture and storage in the top left is one. Direct air capture, these industrial processes, growing trees where they weren't, to put carbon back on the landscaper in soils, or restoring forest systems, crushing up a particular rocks that are oxidized, I'm sorry, then weathered in place that remove that carbon dioxide and then re-burying those things. So each of these have a different land footprint, a different cost, a different water requirement. So when we think about managing the world at a billion ton carbon seal, we've got to think about these other things too. So here is biomass with energy capture produces energy. If we want to use an industrial process to remove CO2 from the air that doesn't use plants, we've got to supply the energy to do that. Biomass energy has a large water footprint, a large land footprint, and you're talking about a billion acres of land potentially to do this at the billion ton scale. So anyway, work like this, this is work led by Pete Smith that we did a couple of years ago, but work like this is to help us to try and understand not just the carbon cycle components to this work, but the interactions that affect other things we value in the world around us. And then lastly, this is a paper that I led that came out this year. People haven't talked about removing methane from the atmosphere. So methane's harder because it's less abundant in the air, but it's also more potent, more powerful as a greenhouse gas than CO2. So we're working on just starting to in a proposed using particular minerals that might allow us to remove that methane from the atmosphere, not easy, will be expensive, but the advantage here compared to CO2 is this is a downhill reaction thermodynamically. So in principle, it doesn't require energy to do that. So that's one thing that my lab's working on. Let me switch to methane just very quickly. Here's a sample of the global methane budget. Now the elephant is carbon dioxide, but methane is the second most important greenhouse gas that we've perturbed. And we have perturbed the global methane cycle far more than we perturbed the global CO2 cycle. So more than half of methane emissions today are human sourced from agriculture and from industrial activity, more than half. So we've more than doubled the natural cycle. So here are fossil fuel production there, agriculture primarily cattle and rice farming. And then here are natural sources, wetlands, natural geologic seeps and such. So our group works on wetland emissions, and then also particularly on the fossil fuel use and production side. Here, this is just a figure that shows you where methane is emitted around the world. The size of the pie is the amount. So primarily in the tropics, where you see green, those are natural sources, blue and gray, are the agricultural and fossil fuel sources. So in the tropics, you have most emissions, primarily or mostly natural, not exclusively. Temperate systems, little smaller, primarily industrially and agriculturally based. And through inventories and such, we can ascribe in that bottom up approach that I mentioned, where these sources are coming from, the number of cattle, where rice is produced, where fires occur from natural emissions and from human sources of fire. Fossil fuel infrastructure, natural wetlands and things like that. This is how we kind of compile some of this information for the integrated, and then look at these sources and what the atmosphere tells us about where methane is being emitted. So if you're concerned about permafrost methane runaway, you're gonna expect to see that up in the north. You go back to this previous slide, there isn't a lot of methane emissions relative to the global cycle in the far north. So we keep an eye on that sort of thing to look for early signs of potential runaway methane production. Okay, let me finish just with a couple of examples from some things we do. In my group, I'm very interested in reducing methane emissions, greenhouse gases from energy infrastructure. So we fly helicopters, we drive cars, we put instruments on top of skyscrapers and take measurements through time to try and attribute sources over cities in different places. I'll give you just a couple of examples. Here's one that was published a couple of years ago, we flew 8,000 oil and gas wells randomly across the United States in a helicopter. This is like a restaurant inspection. You show up unannounced and you film it with an infrared camera, see who leaks, who doesn't and what correlates with those leaks, how big the site is, how old it is, who's running it, what the policy and regulatory framework and inspection framework is for that site. So here's an example, let's see if I can make a video work. So this is using an infrared camera. These emissions are invisible to the naked eye. So you're in your helicopter, you film it, so there's a leak from the top of a tank. Now that's not normal. What's normal is to show up and see nothing at all. But occasionally 1%, 5%, even 10% of the sites, depending on where you are in the United States, this is what we see. So we try and collect this information and then feed that information back to the companies who are working there and also try and use data to make the system cleaner. So another example, City Streets, my group with colleagues in Boston, Nathan Phillips and others, did the first studies of publicly available data in cities. We put new analyzers in cars, laser-based instruments and drove every block of cities. So I'm maybe, I guess, I think I'm likely to say, I'm the only person who's driven every block in the city of Boston. Some of those blocks many times as you're filling out the grid, if you will. So occasionally when we find a large source, it's like fishing, you know, you're trolling and then once in a while, ping, your analyzer goes off and you get a spike. Then when that spike, when that ping is big, we can hop out of the car, sample the gas and look and see whether it's sewer gas or fossil fuel-based gas and attribute the source to that loss. So when we do that, we see a map like this. This is Boston. Boston's not everywhere in the United States. Boston's old. There are pipelines here still that are 100 years old. Right, red, road miles driven. Yellow are spikes, leaks. Number one predictor of a leak in an old city like Boston is old infrastructure. It's not a poor neighborhood, rich neighborhood thing. It's an old neighborhood, new neighborhood thing. We published this work. It's now about five years old, a little old, but the mayor commented on it the next day. At that time, Congress and Markey, now Senator Markey commented on it the next year, Massachusetts passed an accelerated pipeline replacement bill based not exclusively but partly on our work. This allows the companies to front load expenses and be able to recover the cost of those expenses earlier to clean up that pipeline and make repairs that they would have delayed for 10, 20 or 30 years. So it speeds up that repair and replacement of that old infrastructure. So in a sense, everybody wins. Consumers pay about a dollar more a month. However, one thing that many people don't know is that you and I, consumers pay for the gas that goes leaking out of pipeline systems. So we're actually paying for that gas. Out of these 100 year old pipelines. So the consumers will benefit not just economically but because the system will be much safer. And we can show that by comparing cities that have been cleaned up, if you will, where partnerships have led to replacement of those pipelines over sort of a decade, decade and a half time period. So we drove Manhattan. The city still has a lot of leaks and repairs in Manhattan are expensive for obvious reasons. But you can compare it to cities that have had creative partnerships for a decade or more to get rid of their emissions during North Carolina, Cincinnati, Ohio, compared to say Manhattan. So you get one 20th the number of leaks. 90, 95% reduction in leak densities to these programs. So they do work. They're helping reduce natural gas emissions but the motivator isn't climate change. It doesn't matter whether you're a Republican or Democrat. The motivator for people is safety. So these are just some of the justifications from a pipeline framework for doing this outside of the environment. Air quality, hydrocarbons catalyze ozone formation. Rare, very rare events. The natural gas system is safe but accidents still happen and cost us money. Jobs, and we pay a couple of billion dollars a year for lost and unaccounted for gas. All right, just one example, I'll stop here. One thing we've been working on for the last year or so is people's homes. Surprisingly, the whole part of the natural gas chain that's the least studied is what happens after the utility brings natural gas to your home or building. And at that point in time when it crosses the meter it's no longer the utility's responsibility, it's the owner's responsibility. So we're sampling homes for water heaters, stoves, furnaces, leaky pipes, things like that to try and again figure out what's, how much is actually being emitted? And there are some real surprises in this that we're finding and then ultimately trying to work with companies and where needed to try and re-engineer some of these appliances and reduce those emissions. And ultimately, we're gonna need also to electrify our homes as we need to electrify our cars using low carbon sources. So I'm gonna stop there and I wanted to leave time for questions and thanks for your attention. Any questions? You guys are ready for break. Got one here. So Arun mentioned that it's about a 4% natural gas leakage rate that makes natural gas worse than coal. You have an estimate as to what the leakage rate is now? Yeah, a lot of people would say it's closer to two and a half or 3%. And that's in the electricity sector. I think it's fair to say that VPA would tell you it's about one and a half percent, 1.6, 1.8%. I think there's pretty much nobody in the research community who thinks that number is correct. So we're up into the two, we're into the low twos at least. So there are other reasons to support a transition from coal to natural gas, right? The number one source of, well, two largest sources of air pollution deaths in this country, coal-fired power plants and cars. All right, so you get rid of, take coal plants offline and replace them with natural gas or especially renewables and we improve air quality. There's no mercury emitted from natural gas and especially from solar and wind and things like that. So there are other reasons for doing it. But the numbers, we have some work to do to bring the numbers down and ultimately we're gonna need to, if we're gonna keep burning and using natural gas, we need to store that pollution underground or switch to no carbon sources. You had showed a graph that had the CO2 emissions per energy had been about the same over several decades. Why hasn't the increase in use of renewable energy sort of reduced that number? Yeah, it's a great, it's a really fascinating, it's a really fascinating issue and it has in places. That's what it has in the United States. It has in Europe, where as particularly old power plants have been taken offline. So probably the biggest trend in energy, as you all know in the United States has been 40 to 50% drop in coal-fired electricity over the last decade or two in this country. I mean, that's an amazing change, but it takes a long time to do that, right? You spend a billion dollars on a power plant, you don't wanna take that plant offline in year 15 instead of year 30, right? So there's a delay in taking those power plants offline. So that's part of the story. In the US, we're using more fuel for driving, especially for air travel and things like that. And right now there's really no zero carbon commercially viable means to get rid of transportation and air traffic in particular. But elsewhere around the world, it's something else. If you're in India, you don't have natural gas resources to speak of. So India's building a lot of new coal plants, they're using, building a lot of wind and solar too, solar in particular. So the real answer is that other places around the world were building new fossil fuel infrastructure for people who need electricity and because of geopolitical and other reasons too. So most of the renewables coming online around the world are not taking fossil fuel infrastructure offline, they're adding new energy infrastructure into the mix. What's going on in the back? So in many of the, most of the talks we talk about a budget of, with the given budget we have around 15 to 20 years to stay under the 1.5 to 2 degrees Celsius. Yeah, not 1.5. Right. So. Two, maybe. Given the trend that we have observed over the past years where the greenhouse gas emission has been increasing, is there any possibility of actually meeting those 15 to 20 year windows or what do they mean in that scenario, in realistic terms? Yeah, the 1.5 degree budget is sort of the aspirational target of the Paris Agreement. Maybe we'll finish with this question unless there's a quick follow up. The 1.5 degree target is the aspirational goal of the Paris Accord. Is it still possible to reach that target? Absolutely it is. Is it likely we're gonna reach that target? I mean, I'll be honest, no. It's not likely that we're gonna reach that target short of really, well, if we were to reach that target the most likely way we would do it would be to implement massive carbon dioxide and greenhouse gas removal from the atmosphere in sort of a negative emissions approach. Two degrees C, a little more possible. We're not on track right now. We're not even on track right now to meet the Paris Accord agreements which only got us to about 2.7 degrees approximately. So globally we're not reaching that. Is two degrees still possible? Yes it is. Is it odds on favor to make it? Not the way we're going now. But you can't give up. It's all of our job to change that trajectory. That's what we try and do in the Global Carbon Project with other people and groups here at Stanford and elsewhere are trying to do. But I gotta be frank, I'm an optimist at heart and I believe in what we do and I'm gonna encourage you again to get involved. Take advantage of the time the people here bring your expertise and knowledge to help us. But I'll be honest, right now we're not on track to make two degrees. But I would do anything I could to help us get there. Are we good? All right, thank you everybody. Have a great time. Feel free to stop by. Thank you.