[MUSIC] The second thing that crops need, and this is something that often comes up immediately after I, I say what temperature is done is that crops need carbon dioxide, so you might say, well we're emitting lots of that right now, won't that offset, won't that be great? And it's true, you know increased concentrations of carbon dioxide, plants are able to take advantage of that, but what you'll see right now, this is a synthesis of many of these experiments that have been done looking at the effects of increased carbon dioxide on crop, growth crop yields. What you'll see is that the increase here we're talking about, like you know, it's much smaller increases than what we're talking about in terms of decreases for temperature. So, it's not going to be enough to offset the other climate related impacts. So the third thing, that crops need, is adequate soil moisture. Most of our crops I'm focusing again here on serial crops. This is because of the four major crops we grow in the world, provides 70% of the calories that we consume. So, so starting with those, rice, wheat, corn and soybeans, is a good place to start. Most of those crops, are grown in rain-fed conditions. About a third of our crops are irrigated, but still the majority, and especially for poor farmers, are grown in, in rain-fed conditions. This is a showing a plot of, of rainy season rice in India. The overall production and in red and the excuse me, in blue and rainfall in red, and these are deviations from the average. What you can see is that over time, these are very, very strongly coupled. You have a good year of rain, you have a good harvest. You have a bad year of rain, you have a bad harvest. So having enough precipitation, having enough soil moisture is, is really important for crops. And unfortunately, what we've seen, again, when we look at the climate side of this. Is that some really important monsoonal systems. Some really important rain-fed systems, have weakened dramatically. Over the past decades due to anthropogenic emissions. So the Sahel, India, China, have all seen really significant regional precipitation impacts. The third the next thing crops need, is adequate radiation. Again, looking just observationally at what, what has happened, there's been a tremendous global dimming. Surface radiation, total surface radiation has gone down in part because of pollutant emissions, and in part because of changing in cloudy, changing cloudiness patterns, but almost all of it is attributable to, to anthroprogenic emissions. So this is, dimming at the surface at the same time the nature of the radiation reaching the surface has changed. This is called the diffuse fraction. All the pollutants that we've emitted in to the atmos, in to the atmosphere some of them are scattering and they increase the diffused fraction of light, some of them are absorbing. And so, so the nature of radiation reaching the surface has changed. And this is important for crops as well. There's some evidence that crops can grow more effectively with diffuse light. So maybe, maybe not all is, is bad but but this is going to be something that we are going to want to keep an eye on, going into the future. Finally pollutants that we emit are often toxic to plants. So you have potato leaves showing ozone damage. Ozone is a, is a really big important [LAUGH] damager for plants. And some studies have. What some modeling studies have tried to estimate, yield loss due to ozone, and have come up with some staggering numbers so if you look just worldwide again, these four major crops wheat, rice, maize and soy globally we're seeing, you know five to ten percent, a little less for corn is less sensitive. Relative yield loss due to ozone alone, so, think about the, the combination effects of climate including pollutants, and it starts to be very big numbers. These are for the year 2000 estimates. So if we want to step through, a little more systematically, human impacts, there's two real routes anthropogenic emissions multiple mechanisms of our impact on agricultural production. First is emission of long-lived greenhouse gasses. So carbon dioxide is, the one we all know. And the other is short-lived climate pollutants, so things like soot, black carbon, our, our speaker series has focused on some of these. But these have important implications for agriculture as well. So, long-lived greenhouse gases, are obviously contributing to temperature and precipitation changes. But short-lived climate pollutants are also contributing to regional temperature changes and precipitation changes. And they also have direct effects, so they're changing the nature of the radiation like I told you, reaching the surface, surface. And they're also directly toxic to plants, like in the case of ozone. Finally, they, they impact agriculture in another way by, changing snowpack and glaciers, and decreasing overall water availability, I know previous talks has focused on this. We looked at a study, we did a study in India and tried to look at the relative impacts of long-lived greenhouse gases versus short-lived climate pollutants on agricultural yields. And we found that 85% of relative yield losses that we calculated, were due to pollutants, now, I know Professor Romanoff discussed this early, but the beauty of SLCPs is that their atmospheric lifetimes are very, very short. And this is in stark contrast to something like carbon dioxide. So, reducing our emission of SLCPs could have ten to, tens of millions of tons of crop, and this is just in, in India alone. You know, multiply, multiply these numbers by the world and we start to see that there's a real strong potential for important short-term important short-term boost to our ability to produce, produce enough food. And that's my second takeaway message is that we, we could You know, cleaning up the air could have important, really big impacts on our food supply. Okay, as I said before, you know, availability our global food supply is not the whole story, everyone is engaged in the market everyone is involved in the world food economy and so it's very, very important to think about access. There's a lot of ways to think about access, I'm just really going to touch on one, access is you know, we already do a lot of work moving food around the world. One study recently estimated that about 23% of global emissions, were attributable to goods that are traded and that includes food so, so trade is a really big and important piece of the climate picture, but again I would de-emphasize something like food miles, and, and talk about access in a little bit di, of different way. Most of the world's farmers, small-holder farmers, most of the world's poor, are small-holder farmers and, and their lives look something like this. So this is a, little farm outside of Mijer, it was there a few years ago. I like to call this grass-fed beef. This is, you know, a local, organic farm with grass-fed beef. [LAUGH] and [LAUGH], most of, most of, most of the world's poor farmers live in conditions like this. They have a, a hectare or two of land, and they're growing rain-fed crops so their, their, their production season is entirely confined to the rainy season. Which means they are very, very vulnerable to weather shocks. And these weather shocks can have really long term ramifications. A bad year can mean, you know, disastrous outcomes for children's development for, for recovery economically of the family. For things like human capital. Do they send their, their kids to school? It's a very, very sensitive, sensitive system. I would argue that we, we don't want the world to look like this, and so it is really important to think about how we might boost small-holder resiliency. You know, small-holder farmers, when we think about food access, it's really, really important that they be able to produce a surplus, so they can exchange for protein and other calories and nutrients, and their communities depend on that surplus, you know, for other people who want to purchase and barter. So we really need to think about small-holder resiliency. As just one example of this, you know, you could think about irrigation. You could think about lots of ways of helping to break this cycle, or boost resiliency. We've been doing some work in this semi-arid region of Brazil. It's a big dairy producing region. And if you look at what's happened over the past half century, in the state of Bahia as a whole you can see that milk production has gone way up, and most of it's actually been, in increased yields. So not just the number of cows, which is the blue line here. It's been an actually, produ increasing the amount of milk per cow that you get. A notable feature here, is that there was a very big drought in the early 1990s. As you can see, it caused a bunch of you know, loss here. But that the state as a whole recovered. Now, when you look at the poorest part of the state, we don't see that at all. Right? There're almost no yield increases, and then in that big drought it took, first of all, huge losses and then, you know, almost barely, barely recovering by the present. So this is, this is an example of a really not resilient region, right? Not recovering from a climate shock. So we've been doing work trying to help plant new types of forage that simultaneously make yields go up. And also help with, you know, allow for reforestation, so there can be more water content in the ground. A bunch of win-win scenarios. This is just one way that looking at small-holder resiliency can be kind of a win-win solution. Alright, so finally we talked about, you know, the need to have enough food. The need to access food. But then [COUGH] households have to be able to prepare and consume food. I'm just going to talk about one piece of that and that's cooking. Most of the, much of the world. A, a big perce, a big percentage, almost three billion people, depend on solid biomass fuels. In unimproved technologies, for their cooking and space heating needs. If you look at this globally it, it, it won't really come as a surprise where these regions are. They are so heavily dependent on, on biomass burning. This is just a staggering number. Three billion people don't have access to improved sources of energy, for things like cooking for preparing their food. We really have a, a divided world. This has a, a bunch of ramifications. One is that tremendous labor is spent gathering firewood, gathering crop residue, so people can cook. Often this burden falls on women and girls. You know. This is drudgery but there's also a huge opportunity cost to it. This is a big reason why many girls get pulled out of school in developing communities, because they need to do things like haul wood, haul water. In many places, it's unsafe. And in many places it also contributes to deforestation, as communities pass their sustainable harvest limit. Like I said, it'll, it, you know, kind of comes as no surprise where these communities are, but it's worth drawing out that, that these populations that are dependent on solid biomass fuels, are many of the most food insecure places in the world, as well as a very strong relationship. So, this is just one way of illustrating that food security and energy security, are very, very tightly linked. The last thing I'll say about biomass space cooking, is that it it contributes a, a lot to our current climate problem. So cooking with solid unprocessed biomass creates a lot pollutants particulate matter black carbon, ozone precursors gases that create ozone. And we get huge build-ups of pollution, these atmospheric brown clouds. Which have tremendous climate impacts. I know you've already spoken about this in in this series. They have tremendous impacts on climate. And if you'll remember, these, these climate pollutants, these short-lived climate pollutants, are a big part of what's contributing to present, relative, yield losses in climate change. So there are excuse me, in agriculture. So they are already affecting our ability to grow food. It's kind of this vicious cycle, of food and energy insecurity, feeding back on each other. So I'll, I'll, I'll say my, my fourth takeaway is that we could do a lot for both food security and climate change. As well, energy security too by addressing rural energy access. Thinking about ways to get improved cooking technologies to rural communities who are biomass dependent. Okay, I'm, I'm, I'm very well aware that I am standing between you and your own food security so I'll [LAUGH] wrap with some conclusions. Again you've, these are tightly interlinked problems, global hunger and climate change, but I think there are win-win opportunities in there. The first is breeding for future climates, so we really need to make sure yields stay high. We have ways to do that. We need to invest in it. The second is that we could gain a lot immediately by cleaning up air pollution both on the climate and food security front. The third, is that investing in small-holder resiliency is again, a win-win solution, right? We protect local environments, we increase local food access and we just make. Our world's farmers more resilient to climate shocks, which we know are going to increase. And finally, investing in rural energy access can have important feedbacks to our world food system. Alright thank you for staying with me through the end and I look forward to questions. [SOUND]
