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.