[MUSIC] Thanks, it's a, it's really an honor to be here tonight as part of this series. And in particular, I'm humbled to share the podium this evening with Steve and Dan. These are two scholars who I respect tremendously. And my education has consisted in part of reading papers that they have written, so it's, it's really nice to be here. moreover, they've given the best possible introduction for what I'm going to talk about tonight, which is climate change and food security, so thanks to you both. yeah, so what I hope to do tonight is illustrate some of the connections between climate and food security. And, most importantly, I hope to convince you that food security is a powerful motivator for doing something serious about climate change. And also more hopefully, I think [LAUGH], that the food system, our world food system from production to processing to consumption really offers a lot of opportunities for win-win situations. Whereby we might address global hunger and climate change at the same time. So it, if we're going to think about these two issues, climate change and food security the arrows of influence actually go in both directions. Climate change and our, our climate in general impact our ability to grow enough food, impacts our ability to grow enough food. And our food system has important impacts on the climate, and more importantly, sort of our future climate trajectory. Of course, in the spirit of of this lecture series, we could expand this. It's really sort of the food climate system is actually a food energy climate system. And we've heard over the course of this series talks dealing with various of these arrows, so it had a lot on energy and climate relationships. We've talked about the energy that goes into food earlier this evening. We talked about bio-fuels, food going into energy. tonight, I'm going to focus over on this right hand side. yeah, and as I said, my, my hope is to end this series with, with a hopeful message, an optimistic message because I think there's, there's a lot to be done here. So, to start, I'd like to give a working definition of food security. This is a term that gets tossed about a lot. And I want to make sure that we're all on the same page. So, what would a food secure world look like? That's one way of asking what the definition is. I think that a food secure world is one in which all people, at all times, are able to obtain and benefit from appropriate and nutritious foods for an active and healthy life. Now, to make this a little more tractable we can break it down even further. And really when we start thinking about quantifying some of these problems, food security has three dimensions. So the first of these is food availability, and this is the existence of an adequate and stable supply of food. So here we're thinking really at the big, global level. Like, what is the global food supply, and are we able to produce enough food? The second dimension, you know, of course, just producing enough food is, is not enough. The second dimension is actually access and this is, this refers to the ability of people to obtain appropriate nutritious food. Now, almost everyone in the world participates in the world food economy. We are all in the market for energy, for calories, for protein, and for micro-nutrients. Those are the things we need to survive. And everyone from the richest of the rich to the poorest of the poor is engaged in transactions to get those nutrients. Almost nobody in the world lives on what they produce exclusively. So this access issue is very, very important across economic spectrum. The third dimension, if you could call it that, of food security is what I'll call nutrition. And this is the ability to consume and benefit from nutritious foods. So, even if there is enough food and even if you're able to access it, you need to be able to cook it and process it into a usable form. And you need to be in good health to benefit from the nutrients that are in that food. So this is sort of a, a, a broad category. And whereas food availability is kind of at the global scale, access kind of brings it down to a community or household level often. When we come to nutrition again, this is, we often think about it more from the household and individual level. So we have three sort of axes or dimensions of food security that we can use to get a handle on some of these questions. For those who are not as used to thinking about agriculture Steve's talk gave a great introduction and I'm going to, I'm going to build off of that here. So let's start with with availability. As Steve talked about, the, really one of the defining characteristics of the past half century is that we have produced enough food just to narrowly outpace demand. And that we've done that until recently at low, along with lowering the real price of food. So there's been, in the past decade, more volatility and sort of rising prices. But the predominant trend of the past half century has been, we have grown enough food and we have done it for we have made it less costly for people. So we've been tremendously successful at increasing both food availability and food access. Now, of course that has not come without environmental costs. And if we want to think about, sort of, what has the footprint of food production or this global food availability been on climate, it helps to know a little bit about what the what the emissions are from agriculture. So I'm going to talk about that for a second. Over here roughly, depends on how you do the accounting, but roughly, you know, 35 to 40% is emissions from soils. So this is nitrogen emissions from either applied fertilizers that are inor, you know, applied inorganic fertilizers or manure. Roughly the same amount, 35-40% is due to enteric fermentation, cow burps and manure management. And then another 10-15% from rice, and then, the remainder is, you know, from, from other agricultural emissions. The, the big piece of that is burning of agricultural residues. When you put this all together globally, agriculture and deforestation associated land use change, accounts for, again this varies year to year and how you do the accounting, but roughly a quarter to a third of all emissions. Now it's easy to look at this and say, well maybe, maybe all this energy going into agriculture is really bad. This is a big piece of climate warming. Maybe intensification is bad, maybe big ag is bad, maybe technology is bad, but you really need to have a good counter-factual scenario. You have to say what would have been otherwise? What are some likely other, other alternatives? So we tried to answer this question a few years ago, some of my colleagues and myself. And we, we went back and we did a historical accounting of all or of most of the emissions associated with agriculture over the past half-century. And as well as emissions from conversion of native habitats to crop lands, so expansion of crop land and all the emissions that go into producing fertilizers, producing pesticides, emissions from soils, etcetera. And as a snapshot of that, I'm just showing you what we, what we found for 2005, sort of near the end of that period. and, and what stands out is that when you take all these things into account, you know, the energy, the emissions due to producing fertilizers, you know, nitrogen emissions from the soils, rice cultivation, big things. What completely swamps those numbers is land use change associated with expanding agriculture. Now the, the amazing thing [LAUGH] about the green revolution is that it, it, it prevented a lot of land use change from happening. So, to put these numbers in context, we said, what would've happened if you had not had those yield improvements from the green revolution? So, say we'd expanded to meet our present needs expanded production to meet our present needs by expanding crop land. What would've been the, the greenhouse gas impact of that? And, and what we find is that overall intensification has been a tremendous climate winner. Almost by accident, nobody was thinking about climate change when [LAUGH], when the green revolution was happening. We were worried about feeding enough people. But what we find is that if, you know, compared to alternative scenarios intensification saved up to 160 gigatons of carbon. For, for reference, this is about a third of all that's been emitted since industrialization. So, this is one of the tremendous sort of side benefits, again, of intensification. And this is my first take-away for the evening. Which is that if we want to think about win-win solutions for food security and climate, we really need high yields. We need to minimize the expansion of crop land. Now, I don't mean to say that big-ag is perfect. There are a lot of ways we could do this better, but high yields are really, really key moving forward. Okay. Now unfortunately, at the same time that, that we know we want high yields climate change is actually making it more difficult to achieve those high yields. So I'm going to talk a little bit about what plants need, for those of you who aren't farmers or engaged in, in crop production. And I'm going to talk about why it's getting harder now to, to grow these crops with high yields. So the first thing to know is that plants like to grow at an optimal temperature. You can look at these relationships for, for any crop and, and, they look fairly similar. So, what I'm showing you here on the horizontal axis is time accumulated at different temperatures for plants, for for corn actually, over its life cycle. And what we see is that up to about 29 or 30 degrees C yields are pretty flat, but once plants, once corn starts spending a lot time above 30 degrees C, yields drop off tremendously. And this relationship has been derived for, for all the big crops and it, it's very, very similar in form. There's, there's a nice threshold temperature beyond which production drops off. So you can immediately see where I'm going with this. If you just look over the past, excuse me, over the past three decades research has shown that temperature, mostly, some precipitation, precipitation changes, but mostly warming, has actually contributed to significant yield loss already. So yields are getting higher, of course, because of better technology, but they're not getting as high as they would have otherwise because of these temperature changes. The rule of thumb is roughly that without any adaptation, each degree of warming would result in around a 10% relative yield loss for crops. So, when you think about the numbers that Dan was showing you you know, two to four degrees of warming by the end of the century, this starts to be very, very meaningful.
