Deforestation and the Future of the Amazon
Transcript of Part 1: Consequences of Amazon Deforestation
00:00:07.15 I'm Christopher Neill. 00:00:09.01 I'm a senior scientist at the Woods Hole Research Center 00:00:11.26 in Woods Hole, Massachusetts, 00:00:13.18 and I've been working on the Amazon 00:00:16.03 since the early 1990s. 00:00:18.02 The Amazon is the world's largest tropical rainforest. 00:00:20.20 It covers an enormous area 00:00:23.14 of nearly 8 million square kilometers 00:00:25.12 in northern South America. 00:00:27.13 That's about seven-eighths the size 00:00:29.25 of the entire lower 48 states in the US. 00:00:33.00 It's a globally important ecosystem. 00:00:36.01 It's also one that's changing extremely rapid today, 00:00:38.28 largely because of human activities. 00:00:41.05 In this talk, I'll try to explain 00:00:43.14 why the Amazon is valuable, 00:00:46.10 how it's changing, 00:00:47.25 what's driving those changes, 00:00:49.23 and where those changes will likely drive the Amazon 00:00:53.14 in the future. 00:00:55.19 The Amazon forest occupies nine countries. 00:00:58.18 It's an enormous, 00:01:00.24 but still largely intact, forested area, 00:01:03.27 but it's being changed by human activities, 00:01:07.07 largely driven by deforestation 00:01:10.17 and clearing for agriculture. 00:01:12.23 I want to start by talking about what's at stake in this forest 00:01:16.06 -- what do we lose when forest is converted to other uses? 00:01:19.27 And how might we use what we know about the Amazon 00:01:26.07 to guide management and conservation of Amazon forest 00:01:28.20 into the future. 00:01:30.21 The Amazon contains an enormous storehouse of biodiversity. 00:01:34.14 Just an as example, it has maybe 1300 species of birds, 00:01:38.21 1800 species of fish 00:01:41.02 -- about 40% of those fish probably are not yet described -- 00:01:45.16 it has enormous tree diversity, 00:01:48.10 probably 12000 or more species of trees alone, 00:01:51.14 and there are more species in one hectare of Amazon forest 00:01:55.01 than there are in all of Europe. 00:01:57.04 And it has 3000 species of plants. 00:02:01.06 So, there's just a... 00:02:03.09 it's evolved under a very stable, moist climate, 00:02:07.18 warm climate regime for hundreds of thousands of years, 00:02:11.04 which has led to this enormous diversity. 00:02:13.15 It also contains globally important stores of carbon. 00:02:17.28 The atmosphere, today, on Earth, 00:02:20.03 contains about 850 billion metric tons of carbon. 00:02:24.13 Humans, by burning fossil fuels, 00:02:27.09 have contributed about 255 billion metric tonnes. 00:02:30.24 Tropic forests today, on Earth, 00:02:33.29 contain 270 billion tonnes of carbon 00:02:36.00 -- that's more than humans have put into the atmosphere to date. 00:02:39.08 We need to keep that carbon out of the atmosphere 00:02:42.03 to avoid even more dramatic climate changes on Earth, 00:02:45.21 and the Amazon forest, alone, 00:02:48.19 contains about a third of that tropical forest carbon, 00:02:51.10 maybe about 86 billion metric tonnes of carbon. 00:02:55.00 So, thinking about ways of conserving the forest, 00:02:57.23 keeping that carbon in trees and out of the atmosphere, 00:03:00.28 is extremely important. 00:03:03.16 The Amazon is such a large forest that it 00:03:08.03 also regulates the regional South American 00:03:11.17 and even global climate. 00:03:13.10 The Amazon river itself is 00:03:16.20 larger than the next six largest rivers of Earth combined. 00:03:19.18 It contains 20% of the Earth's fresh water. 00:03:22.17 And roughly 50% of the rain 00:03:25.18 that gets delivered onto the Amazon forest 00:03:28.02 is recycled water that has been transpired 00:03:30.27 through the very large cover of trees 00:03:36.05 in the Amazon rainforest. 00:03:38.02 The Amazon is also important because it 00:03:42.04 provides services for people 00:03:43.26 -- people live and use the Amazon. 00:03:45.19 There are at least 220 ethnic groups 00:03:48.17 that live in the Amazon. 00:03:50.16 There are 170 languages that are spoken in the Amazon. 00:03:54.22 And while these 220 groups are probably... 00:03:57.17 are way less than the probably 00:04:00.04 1000 or so groups that existed before European settlement, 00:04:03.15 they're extremely important, diverse, 00:04:06.08 and an absolutely important component of the Amazon forest. 00:04:09.15 And, like this young girl with a Pintado catfish on the screen, 00:04:14.09 these forests are used by people in a lot of ways, 00:04:18.03 for food and sustenance. 00:04:20.11 But today the Amazon is at a crossroads. 00:04:24.02 That crossroads is caused by the intersection of several forces. 00:04:29.23 The driving, overall force is deforestation, 00:04:32.27 the clearing of forest for agriculture. 00:04:35.22 That leads to fragmentation. 00:04:38.20 The Amazon basin has been wet and green for a very long time, 00:04:44.04 it has not evolved with fire, 00:04:46.11 but the intersection of deforestation and fragmentation 00:04:50.06 and climate 00:04:52.11 leads to increased incidence of fire in the Amazon, 00:04:54.08 and I want to talk about why that's happening 00:04:56.08 and its consequences. 00:04:58.09 And the Amazon has been a site of the expansion of agriculture. 00:05:01.03 It's one of the last remaining areas of the world 00:05:04.15 with adequate rainfall, 00:05:06.09 where agriculture can expand, 00:05:08.22 and agriculture has been expanding 00:05:10.18 and it will continue to expand, 00:05:13.04 and it's important to incorporate 00:05:15.16 our understanding of Amazon ecology 00:05:17.22 into the ways that agriculture might be expanded 00:05:21.22 in tropical regions in the future. 00:05:23.17 And last, the global climate is changing, 00:05:25.27 and that's going to influence the Amazon 00:05:28.20 and it's going to interact with all these other factors. 00:05:30.20 Alright, let's take a look at these. 00:05:32.19 The Amazon has had, historically, 00:05:35.23 from the 1980s through the early 2000s, 00:05:39.16 very high deforestation rates. 00:05:41.23 Now, I live in Massachusetts and I like to show this graph 00:05:45.21 because it shows that through the early 2000s 00:05:48.03 the rate of clearing in the Brazilian portion of the Amazon alone, 00:05:51.28 which is the vast majority of the area and the deforestation, 00:05:56.15 was something on the order of 20000 square kilometers a year. 00:05:59.27 The area of the state of Massachusetts is 22000, roughly, square kilometers. 00:06:04.24 So, we were losing, during this period, every single year, 00:06:07.28 a forest the size of Massachusetts. 00:06:11.14 Most of that clearing during that period was for pasture. 00:06:14.28 Pasturing was a way of people claiming land 00:06:18.21 and using it for agriculture 00:06:21.23 in a not very intensive way, 00:06:25.01 and raising beef over a lot of that area. 00:06:28.24 That was the primary use of forested... 00:06:32.02 cleared forest land through the early 2000s. 00:06:35.15 That's changing and I'll talk about that 00:06:38.11 when I talk about agricultural expansion. 00:06:40.08 Deforestation leads to fragmentation. 00:06:43.07 This picture, here, 00:06:45.25 is an image that shows clearing for agriculture 00:06:51.00 on one side of the screen 00:06:53.00 and a forested reserve on the other. 00:06:55.14 So, it makes two points. 00:06:57.10 One is that when you clear forest, 00:06:59.11 you create lots of edges and lots of patches. 00:07:01.19 those have important ecological consequences. 00:07:04.05 It also shows that when you 00:07:07.26 draw boundaries for protected areas, 00:07:09.29 that that's a very effective mechanism 00:07:12.10 for keeping forests standing. 00:07:14.26 What does fragmentation do? 00:07:16.22 It does a lot things, 00:07:19.01 but one of the most important is 00:07:21.24 it accelerates extinction in fragmented forest. 00:07:26.24 This is just a plot of the proportion of species 00:07:30.11 that go extinct versus the area of fragments. 00:07:34.00 It's from a marvelous study done over decades, now, in Manaus, 00:07:37.23 called the Biological Dynamics of Forest Fragments Projects, 00:07:41.05 and it shows clearly that extinction rates 00:07:45.00 are low in large fragments, 00:07:46.28 over to the right of this graph, 00:07:48.27 and high in small fragments. 00:07:50.22 So, you isolate 1 hectare of forest, 00:07:52.23 you lose a third or more 00:07:57.28 of the total number of species in that fragment 00:08:00.03 over several decades 00:08:04.14 of experimental study shown by this work. 00:08:07.16 So, the other new phenomenon in the Amazon, 00:08:11.28 from my perspective, is fire. 00:08:14.02 Amazon forest is moist for much of the year, 00:08:18.07 it's green for most of the year 00:08:20.19 -- or, all of the year over most of the forest, I should say -- 00:08:26.27 and for that reason it's not very flammable. 00:08:28.22 Right? 00:08:30.03 Most of the Amazon forest, 00:08:32.05 aside from some very small edges near that Brazilian cerrado, 00:08:34.06 or savannah, 00:08:36.13 did not evolve with fire as part of its ecological history. 00:08:40.10 So, you have this enormous area of evergreen forest 00:08:43.20 that is very fire-resistant. 00:08:45.23 Now, why is that? 00:08:47.18 That's because tropical rainforests of the Amazon, 00:08:51.03 over much of the Amazon area, 00:08:53.14 have very deep roots. 00:08:55.02 The soils are very, very deep. 00:08:57.08 They store water over many meters, 00:08:59.24 10 or 20 meters of soil profile. 00:09:02.26 So, it was discovered by Dan Nepstad and his colleagues, 00:09:07.23 in the early 1990s, 00:09:09.24 that these roots penetrated to 3, 5, 8, 10, 00:09:13.21 even 15 meters. 00:09:15.16 They're allowing those trees to access water. 00:09:18.11 So, those trees can sustain 00:09:20.29 a green forest canopy 00:09:23.00 during extremely dry periods of the year, 00:09:26.10 and much of the Amazon is dry for many months 00:09:28.15 -- almost no rain -- but the forest stays green. 00:09:32.04 This graph just shows a plot of forest root profile 00:09:36.03 versus a managed pasture root profile. 00:09:39.03 When you replace the forest with the pasture, 00:09:41.13 you decrease the number of roots going down 00:09:43.25 and the pasture ecosystem turns brown in the dry season. 00:09:48.10 When it turns brown, it becomes flammable. 00:09:50.00 So, one of the things that happens, 00:09:52.21 and I'm going to walk you through 00:09:56.02 this slightly complex graph, 00:09:57.23 is that, in the dry season, 00:10:00.14 when you have pasture, 00:10:03.22 the leaf area and the brownness increases, 00:10:06.07 so the leaf area goes down. 00:10:07.28 So, if you look here and here, 00:10:10.23 this leaf area, actually, in pasture, declines, right? 00:10:13.18 And the forest leaf area actually stays very constant, 00:10:16.25 so the forest stays green and the pasture turns brown. 00:10:20.00 What that does is here... 00:10:22.22 whereas in the forest, here, 00:10:25.00 the window in which the ecosystem is dry enough to burn 00:10:28.29 is minuscule, right? 00:10:30.18 And the chance that there is an ignition source 00:10:33.05 coupled with when it's dry enough 00:10:35.12 almost never happens. 00:10:36.22 But that window is dramatically increased in pasture. 00:10:40.18 So, you've put, now, a very flammable ecosystem 00:10:43.22 right adjacent to a forest ecosystem 00:10:46.09 that never really burned much, 00:10:49.11 and what happens is that fires 00:10:53.04 that start in pastures, either intentionally or accidentally, 00:10:55.25 now sort of move into the forest. 00:10:58.20 They creep into the understory, 00:11:01.00 they don't do a lot of damage the first burn, 00:11:03.04 but they set the forest up for future change. 00:11:06.27 So, there's a lot of this fire, now, this black area. 00:11:09.18 In this paper by Mark Cochrane, 00:11:12.02 he clearly showed that there's a lot of fire 00:11:14.21 sort of creeping in from the edges of pasture, 00:11:16.19 a consequence of fragmentation. 00:11:20.22 Another new phenomenon 00:11:23.02 that dramatically expanded in the 2000s 00:11:26.12 was the dramatic expansion 00:11:33.06 of crop agriculture into the Amazon. 00:11:35.04 So, remember, 00:11:37.18 previous agriculture was largely cattle ranching 00:11:39.18 -- growing of grass, 00:11:42.09 raising of cattle at fairly low densities. 00:11:43.26 Now, today, there's been a 00:11:48.05 dramatic expansion of cropping in the Amazon. 00:11:50.02 Now, 30-40 years ago, 00:11:52.14 the conventional wisdom was, 00:11:55.29 well, you can't grow crops in the Amazon. 00:11:57.18 The soils are too acid, 00:12:00.09 the aluminum is toxic to the plants, 00:12:02.21 the phosphorus fertility is very, very low. 00:12:04.26 Well, those barriers can be overcome 00:12:08.12 with modern farming methods 00:12:10.11 -- fertilization, liming, pesticides to control tropical pests. 00:12:15.05 So, cropland has just expanded very dramatically in the Amazon 00:12:19.10 since the mid-2000s. 00:12:21.08 The principal crop has been soybeans, 00:12:23.09 but, more and more, 00:12:25.11 soybeans have been crown 00:12:29.05 together with a second crop of corn or cotton, 00:12:31.10 and this is moving... 00:12:33.07 has moved very rapidly into the Amazon 00:12:34.29 from the southern end of the Amazon, 00:12:37.03 where there's a seasonal dry season 00:12:39.00 that works to control pests and diseases 00:12:41.16 fairly effectively. 00:12:43.26 This has been a fruit of a green revolution 00:12:46.19 that's developed crop varieties 00:12:49.04 that can grow in hot tropical climates, 00:12:52.06 like the soybean varieties that can adapt to tropical day length 00:12:55.05 and the ability to use large amounts of fertilizer and pesticides. 00:12:58.07 Soybeans is interesting 00:13:01.22 because soybeans is now a global commodity, 00:13:04.02 so, where I work in the Amazon, 00:13:05.25 you see trucks like this lined up on dirt roads 00:13:08.22 more than 1000 miles from the port. 00:13:11.04 They get loaded with soybeans from the Amazon, 00:13:13.22 they travel on dirt roads, 00:13:15.21 and then reach paved roads, 00:13:17.14 and so there's this global transport network 00:13:19.23 that takes soybeans from the central Amazon, 00:13:22.25 you know... agricultural region, 00:13:26.13 all the way to other parts of the world. 00:13:28.12 And what's interesting is that, since roughly 2000, 00:13:32.24 exports to China, here, 00:13:34.28 this blue slab on this graph, 00:13:38.08 have increased dramatically, 00:13:40.23 and China now dominates the Amazon soybean export market. 00:13:45.07 So, we've moved from a world in which 00:13:49.00 soybeans were mostly grown outside the Amazon 00:13:50.28 to a point where Brazil is now 00:13:53.07 the world's largest soybean exporter, 00:13:55.02 and China has been a major destination 00:13:58.00 for Amazon soybeans in very recent years. 00:14:03.09 The other change that's occurring in the Amazon is climate. 00:14:06.21 This map shows, in red, 00:14:09.27 the areas where there are significant numbers of dry months. 00:14:12.20 So, if you look here, 00:14:14.26 in the southern Amazon region... 00:14:17.02 and this just shows the Brazil... 00:14:20.27 the place, here, where I'm pointing is 00:14:25.07 pretty much the area of very dramatic agricultural expansion, 00:14:28.01 there are 4-5 dry months. 00:14:31.10 What's important, now, is those dry months 00:14:33.25 are setting the Amazon up for 00:14:36.07 increased interactions between fire and drought and agriculture, 00:14:40.08 over very large areas. 00:14:42.06 I want to talk about drought, 00:14:44.12 because it's a very hot topic in the Amazon right now, 00:14:47.09 and it's important to understand 00:14:50.03 what the Amazon might look like 00:14:53.00 if droughts increase, and El Niño’s 00:14:55.19 -- strong El Niño’s, especially -- 00:14:58.01 bring very dry conditions to the Amazon. 00:14:59.22 This is a picture of an experiment that was done 00:15:02.09 in the central Amazon, near the city of Santarém, 00:15:05.25 and it was called the Dry Forest, 00:15:09.11 or Seca Floresta, Experiment. 00:15:11.08 And this involved placing 00:15:16.08 about 7000 plastic panels in the forest understory 00:15:18.26 to exclude rain, 00:15:21.17 so, in this experiment, rain was excluded. 00:15:23.21 About 60% of the rainfall that fell 00:15:27.25 in the rainy season on this forest was intercepted 00:15:29.21 and moved away, 00:15:31.20 and they studied, over several years, 00:15:33.17 the responses of the trees. 00:15:35.10 And it was very interesting 00:15:37.11 and I'll just highlight one of the results. 00:15:39.10 Drought induced mortality of large trees, 00:15:41.27 and that mortality didn't start in the first year, 00:15:45.05 it wasn't dramatic in the second year, 00:15:48.05 but after three years of induced drought 00:15:51.26 there was a very dramatic increase in tree mortality. 00:15:56.06 And this, really, is an interesting thing, 00:16:01.07 because fire, when it moves through the understory, 00:16:03.06 tends to kill small trees. 00:16:04.24 Drought tends to kill the big trees 00:16:06.14 and it's the big trees that have all the carbon, 00:16:08.17 and it's the big trees 00:16:11.02 that provide the microclimate and other conditions 00:16:13.13 that sort of maintain the forest. 00:16:15.23 So, there's a very big 00:16:20.01 potential impact of increased drought 00:16:22.18 when they come, sort of, year after year after year. 00:16:24.29 The other effect of drought 00:16:27.20 is that it dramatically increases the potential for fire in the forest 00:16:31.28 and fragmented landscape. 00:16:33.18 So, here's a plot of years on the bottom 00:16:36.25 with the years, here, 00:16:39.27 of the water deficits, right? 00:16:43.29 So, you have... these are very dry years in these years, here, 00:16:50.22 where you've got this low water potential. 00:16:52.13 And in the same years where you have dry conditions, 00:16:54.15 this bar graph here is the area of Amazon that was burned. 00:16:58.07 So, when you have dry conditions, 00:17:00.26 like over here in 2010 or 2007, 00:17:03.18 you have a much larger area of Amazon forest that's burned, 00:17:08.25 in the larger Amazon forest region. 00:17:11.19 So, you set up that interaction: 00:17:14.15 drought plus fire means more forest degradation. 00:17:18.20 The worry is that this phenomenon, 00:17:22.11 this interaction, 00:17:24.18 may set up a tipping point where you actually 00:17:27.05 induce Amazon forest to become savannah. 00:17:29.08 You change the vegetation 00:17:31.01 and induce more grass, 00:17:32.19 which begets more fire, 00:17:34.21 and you actually change, over a significant fraction, 00:17:37.09 20-30% of the Amazon... 00:17:39.29 savannah-like conditions in a new global climate, 00:17:43.17 with longer dry seasons 00:17:46.21 and more potential occurrence of multi-year droughts. 00:17:50.03 So, what is the Amazon's future? 00:17:54.25 The good thing is the Amazon is still largely forest. 00:17:58.16 This is a map, again, 00:18:01.05 of the Amazon over nine countries, 00:18:03.27 and what you see in orange, at the bottom, 00:18:07.22 is agriculture expanding; 00:18:10.01 the purple is pasture, which has largely been focused 00:18:12.12 and occurring in the southern and eastern Amazon; 00:18:15.10 but large areas of the basin are still forested. 00:18:18.11 The dark green areas are forest reserves. 00:18:21.16 Those reserve areas have grown 00:18:24.26 and, in fact, Brazil has expanded 00:18:28.13 its protected area network 00:18:30.19 very significantly since the mid-2000s. 00:18:33.20 The other bright spot is that, since 2000, 00:18:38.01 deforestation rates in the Brazilian portion of the basin, 00:18:40.08 which is where the major deforestation was occurring, 00:18:42.27 have dropped dramatically since that period of high deforestation 00:18:47.24 that I talked about, through the early 2000s. 00:18:51.02 In fact, Brazil has gone from having deforestation rates of, 00:18:55.25 say, 20000 square kilometers a year 00:18:58.07 to down in the range of 5000 square kilometers, 00:19:01.08 where it's almost a 75% drop in deforestation. 00:19:05.02 And that occurred for a number of reasons. 00:19:07.08 One is better policing of illegal deforestation. 00:19:12.17 Another is expansion of protected areas. 00:19:16.11 Another region, which is very important 00:19:18.26 now that Brazil is selling soybeans and corn 00:19:22.03 into the international market, 00:19:24.11 is those markets demand 00:19:27.13 that those agricultural products 00:19:30.19 be produced in a more sustainable way. 00:19:34.23 And this was a protest in the central Amazon 00:19:37.04 carried out by Greenpeace, 00:19:39.14 that triggered a series of events 00:19:42.01 that led to a moratorium on the growing and selling of soybeans 00:19:45.14 into international markets, 00:19:47.12 from areas that were cleared after 2006. 00:19:51.20 And what this did is it forced agriculture 00:19:57.08 to occupy lands that were already cleared, 00:20:00.04 rather than the clearing of new land. 00:20:03.16 And I think, if we look forward to the future of the Amazon, 00:20:07.04 an absolutely major, important question 00:20:11.07 is how Brazil and other Amazon countries 00:20:17.17 manage agriculture in ways 00:20:19.29 that allow that agriculture to intensify, 00:20:22.04 to produce more on less land, 00:20:25.19 and act as a reducer of the need to clear new land, 00:20:29.29 to put new land into production. 00:20:32.20 And there's very good evidence that this is already happening. 00:20:35.24 Here's a plot of soy production and beef production, 00:20:40.20 and, remember, the deforestation started dropping in 2006. 00:20:44.24 What it showed is that reducing deforestation 00:20:49.19 doesn't have to lead to a decline in commodity production, 00:20:52.08 either soy or beef. 00:20:54.05 The yields of soy have remained fairly constant. 00:20:56.26 The yields of beef 00:20:59.01 -- that is, the ability to grow cattle, rather than at 1 head/hectare, 00:21:03.29 at 2 or more heads/hectare -- 00:21:07.21 have allowed more beef to be produced on less land. 00:21:09.20 So, beef production, even in the face of falling deforestation, 00:21:12.26 has been sustained without... 00:21:16.06 the beef production has been sustained 00:21:20.19 on a smaller total area of pasture. 00:21:24.05 I think this is part of the way 00:21:27.22 we need to think about managing agriculture, 00:21:29.25 which is the driver of most of the deforestation in the Amazon going forward. 00:21:35.15 So, that's an overview of the drivers 00:21:38.22 and the ecological forces 00:21:42.19 interacting and shaping the future of the Amazon 00:21:44.16 -- very, very large questions remain. 00:21:46.07 One of the ones that I'm most interested in, 00:21:48.18 and that I'm actively working on, 00:21:51.00 is, how can agriculture intensify 00:21:54.09 without increasing environmental impacts to air and water? 00:21:57.01 And what are these impacts? 00:21:58.12 Well, they're greenhouse gas emissions from agricultural fields, 00:22:00.24 they're emissions of methane from cattle production, 00:22:03.11 they're emissions of nitrous oxide from agriculture 00:22:06.00 when you apply large amounts of fertilizers, 00:22:08.18 which is required for growing, especially two crops, 00:22:13.16 in the Amazon. 00:22:14.28 So, those questions are, how can that be managed? 00:22:17.07 How can we precisely use fertilizer 00:22:20.28 and manage agriculture to reduce impacts? 00:22:23.26 Will we end up, 00:22:26.10 if we're using lots of fertilizer, 00:22:28.15 in these now largely agricultural landscapes, 00:22:30.11 will those fertilizers move from land into streams? 00:22:33.26 And result in the degradation of water quality, 00:22:37.05 like we see in many regions, 00:22:40.25 say, the Mississippi Basin or south Florida 00:22:43.20 or the East Coast, Chesapeake Bay, of the United States? 00:22:45.23 That's a really big question, 00:22:47.22 and this intensification is just now beginning, 00:22:50.07 in the long-term time sense. 00:22:52.17 So, we need to understand that and that's a very big question. 00:22:55.21 The other big question that I think is even more and important 00:22:59.06 and, in some ways, harder and more challenging to address, 00:23:02.11 but we can make a lot of progress, 00:23:05.11 is how much forest can be cleared 00:23:07.15 before we reduce rainfall over the remaining forest, 00:23:13.12 and hence sustain this evergreen forest 00:23:16.01 and prevent forest degradation? 00:23:18.22 And sustain the intensive agriculture 00:23:21.22 that we're now depending on to be a bulwark 00:23:24.11 against the need to clear new forest land? 00:23:27.11 If 50% of the rain is coming from evaporated water... 00:23:30.20 you evaporate much less water from cropland than forest, 00:23:34.15 so you absolutely have to maintain 00:23:39.15 a certain amount of that forest to generate the rainfall 00:23:42.25 that you're now counting on to sustain the forest 00:23:45.12 that you're trying to protect, 00:23:47.22 and to produce agriculture and crops 00:23:50.21 in a more intensive way. 00:23:52.12 That's a big unknown, 00:23:55.00 I think that's an absolutely critical area of future research and a big unknown. 00:23:58.02 We think that that number is more than half of the Amazon forest 00:24:04.07 -- we're approaching 25% of the total Amazon forest cleared -- 00:24:08.16 so we're reaching a point where we may see 00:24:12.17 these irreversible effects. 00:24:14.18 But I think that it's both the worry and the hope, right? 00:24:17.08 We have to intensify agriculture in the Amazon 00:24:20.01 to be able to have agricultural production, 00:24:23.19 it's... agricultural crops are Brazil's number one export, for example, 00:24:28.16 but we also need that forest to sustain this system 00:24:31.21 that we're counting on as a way of protecting the climate. 00:24:38.18 So, that's an introduction to the Amazon, 00:24:43.08 why it's important, 00:24:45.07 how it's changing, 00:24:47.12 and how it might change in the future. 00:24:49.07 There's progress, a lot of progress has been made on reducing deforestation 00:24:51.25 in the last decade. 00:24:53.20 It's still a challenge to reduce deforestation to zero. 00:24:56.03 Brazil has pledged to reduce deforestation to zero by 2030. 00:25:01.08 That remains a real challenge, but I think now... 00:25:04.19 I wouldn't have said this 15 years ago, 00:25:06.07 but it remains a real possibility. 00:25:10.12 I'd like to acknowledge my collaborators in this work 00:25:13.25 at the Marine Biological Lab 00:25:16.12 at the Woods Hole Research Center. 00:25:18.17 Also, our wonderful NGO collaborators 00:25:20.27 at the Institute for Amazon Environmental Research, 00:25:23.04 based in Brasilia. 00:25:25.05 The University of São Paulo, the University of Potsdam, 00:25:27.19 Max Planck Institute for Biogeochemistry, 00:25:30.04 Brown University, 00:25:32.11 and also to Grupo Amaggi for giving us permission 00:25:35.19 to work on a giant soybean farm in the state of Mato Grosso 00:25:38.17 in Brazil. 00:25:40.05 This work that I've talked about has been made possible 00:25:42.23 by a wide variety of funding sources, 00:25:44.25 including from NSF, NASA, 00:25:47.10 Gordon & Betty Moore Foundation, 00:25:49.16 the Research Foundation for the State of São Paulo, 00:25:51.26 and the Brazilian national science agency, CNPq.