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Vida e Tecnologia
  • 04/05/2025
NOVA-S52E08-Secrets of the Forest
NOVA-S52E08-Segredos da Floresta

Segredos da Floresta

Acompanhe cientistas em uma busca para entender como ecossistemas florestais complexos podem ajudar a resfriar nosso planeta.

NOVA PBS – 2025
Transcrição
00:00There are more trees in Earth's forests than stars in our galaxy.
00:19Could they be key to the quest to cool our planet?
00:24All of these plants are taking up the CO2 that's in the atmosphere.
00:28How much carbon can forests soak up?
00:32And what would we need to do to maximize this effect?
00:36To answer these questions, scientists are on a mission to decode the secrets of our forests.
00:44You can feel the presence of everything that is needed to keep us alive.
00:50Investigating how complex forest ecosystems work.
00:53The more diversity that you have, the more diversity can exist.
00:58Examining the role of everything from fungi hidden beneath our feet.
01:03This is live. We're watching the fungi move nutrients right now.
01:09To the bugs, birds and even humans.
01:12Every plant, every animal has a different role in the whole ecosystem.
01:16Calculating how they can all interact to help cool a warming planet.
01:23Secrets of the Forest, right now on NOVA.
01:26The Forest, right now on NOVA.
01:29The Forest, right now on NOVA.
01:31The Forest, right now on NOVA.
01:33The Forest, right now on NOVA.
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01:55Within every forest is a story with many threads.
02:16The overstory.
02:21The understory.
02:25A story of such intricacy, it challenges the greatest minds with its complexity.
02:34As scientists learn more about the extraordinary chemistry of these ecosystems, they're asking
02:42a provocative question.
02:45Could forests offer a natural way to help cool our planet, by removing carbon from the
02:52atmosphere?
02:53I would be surprised to find anyone who doesn't feel more at peace in a forest like this.
03:15You can feel the presence of everything that is needed to keep us alive.
03:28Tom Crowther is an ecologist based in Switzerland, who believes that healthy forests hold the
03:35key to keeping our planet from overheating.
03:39This is what distributes the nutrients throughout the entire forest.
03:45This is a saprotrophic cord-forming basidiomycete fungus.
03:48This is a saprotrophic cord-forming basidiomycete fungus.
03:49Oh my god, this is a salaranda.
03:59So beautiful.
04:00This is a natural forest with all the healthy mixture of species that you need to support
04:13the immense abundance of life.
04:16But also importantly, to lock away lots of carbon.
04:21Tom is trying to figure out the potential of forests to absorb carbon from the atmosphere
04:27through photosynthesis.
04:29This chemical reaction enables a tree to build its solid structures from little more than
04:35air and water.
04:39Inside every leaf, special parts of the cells take carbon dioxide molecules from the air,
04:47and combine them with hydrogen from water to create sugars that will be used to build wood.
05:00This astonishing process is powered by light from the sun.
05:05And that transfer of carbon from the air happens in every single tree on the planet.
05:15At NASA's Goddard Space Flight Center, Lola Fatoyimbo uses satellite data to monitor the effect
05:22that trees and plants have on the carbon dioxide in our atmosphere.
05:27Everything that you're seeing here in the red and orange tones is CO2 moving across our planet.
05:33You can really see how they're swirling around, moving almost like a river.
05:39And you also see that it's not distributed evenly.
05:42Most of it is actually in the Northern Hemisphere.
05:45And this is because most of the land masses and most of the emissions come from the Northern
05:50Hemisphere.
05:55As we get into the spring months, and you have trees greening, you have grasses growing,
06:00you have photosynthesis happening.
06:02All of these plants are taking up the CO2 that's in the atmosphere and concentrations are going
06:07way down.
06:09You don't see all this red anymore in the North that we did before.
06:14This is the system that has been regulating how much carbon dioxide is in our atmosphere
06:18for millions of years.
06:22Biologists like Lola and Tom want to harness the natural power of forests to help absorb
06:28carbon.
06:29That's what these plants do.
06:32They literally capture carbon from the atmosphere and they store it for different periods of time
06:37in their biomass and in the soil below.
06:39And that process of carbon capture is a ready-made tool in the fight against climate change.
06:47Tom estimates that over the course of history, humans have felled almost half of the world's
06:53forests.
06:54So, could restoring lost forests absorb enough carbon to help slow climate change?
07:02To find out, Tom and a team built a computer model to estimate the potential.
07:08So we collect data from all over the planet and that can show us there's about 0.9 billion
07:13hectares of land outside of urban and agricultural land where forests might naturally be able
07:18to regenerate.
07:21That's a big chunk of land that would be able to capture a staggering amount of carbon.
07:28Calculations suggested that to capture this carbon, there was enough land to support an
07:33extra trillion trees, a seductive idea that made headlines around the world.
07:40It just went viral beyond anything I could have been prepared for.
07:44And I think that alliteration, trillion trees, was both a blessing and a curse.
07:49In one way, it captured everyone's imagination, great, we bring back a trillion trees and we're
07:53going to be flying.
07:55But the downside was, everybody thought that meant planting trees.
08:00Somehow it wasn't about the forest, it was about the trees.
08:05And that is where things started to go wrong.
08:10It nearly finished all of our careers.
08:16Companies and governments were under a lot of pressure to limit their emissions.
08:19They saw this as a chance to just bang a load of trees in the ground and then they don't
08:24need to cut emissions.
08:26The projects announced, as a result of our paper, saying, don't worry, we're going to
08:31buy up land and we're going to plant trees.
08:36In the rush to grow trees, people ignored the supporting environment that exists in a forest.
08:45As an ecologist and member of the citizen Potawatomi Nation, Robin Wall Kimmerer knows the importance
08:52of biodiversity in a forest.
08:56The interconnections between species have long been understood by many indigenous people around
09:02the world.
09:03There are places on the planet where biodiversity continues to thrive.
09:09And those places are, by and large, in indigenous homelands.
09:16Biodiversity is the sum total of all of the organisms that are here.
09:19And you think, well, why does it matter?
09:24In a forest which is self-generating, you get all the different forms of trees and the
09:31understory and the mosses and the fungi and the birds all in relationship.
09:35It's this beautiful web that doesn't really exist in a monocultural plantation.
09:42When Tom's paper was published, many quite literally couldn't see the forest for the trees
09:49by planting rows of single tree species to capture carbon instead of reducing carbon emissions.
09:57This greenwashing is one of the most insidious threats to climate change and biodiversity.
10:03And through this paper, in some people's minds, I had become synonymous with greenwashing.
10:11I still regret how I handled that paper.
10:15It's the hardest thing to be hated by people that you agree with.
10:19I just stayed in the flat reading everything in social media and it just like, yeah, there's
10:29no response.
10:30You don't know.
10:32I was just crippled.
10:33I didn't know what to reply to and what not.
10:35I just wanted to say I'm sorry to everyone.
10:44There was a point where I was like, let's drop out of this.
10:48I don't need this in my life anymore.
10:51But that was weighed up against this absolute desperation to show the world how much carbon
10:58can be captured with healthy biodiversity.
11:06Tom and his team decide to set the record straight.
11:10They begin building a new, more accurate computer model that shows the potential of the whole
11:15forest to capture carbon.
11:19Working with more than 200 scientists around the world, they set out to estimate how much
11:24carbon could be stored in each part of the forest ecosystem, starting with the trees.
11:42This is the Osa Peninsula in Costa Rica, home to one of the world's last remaining old-growth
11:49tropical forests.
11:51Ecologist Rebecca Cole has studied this forest for decades.
12:06There's no other rainforest that I've been in where the trees are this tall and it's magnificent.
12:09It's kind of like being in the cathedral.
12:15In old forests like this, individual trees can survive for hundreds of years and can store
12:21huge amounts of carbon.
12:23We have a giant emergent tree.
12:27It's probably 300, 400 years old.
12:33Wood is about 50% carbon, so there's a huge amount of carbon stored in a tree this size.
12:41We have photosynthesis happening up there with leaves and sending carbon in the form of
12:45sugars coming down through the stem and out into the root system.
12:52Trees take carbon from the air and move it through their bodies, inside living cells that act as
13:10long, thin tubes.
13:15These flows feed the tree, using the carbon to create the wood of its trunk, branches and roots.
13:29At the same time, water and nutrients from the soil are pulled upwards through the tree.
13:40When the water reaches the leaves, it's stored, then used in photosynthesis, or released into
13:48the air.
13:49The tree is essentially breathing in carbon dioxide and exhaling oxygen.
14:07By measuring individual trees, researchers like Rebecca can estimate how much carbon is held
14:13in the trees of a given area of forest.
14:18Diverse forests, which support older, bigger trees, can hold nearly twice as much carbon
14:24as plantations of younger trees.
14:36In Zurich, Tom and his student, Li Dong Mo, are using tree data in their computer model
14:42to estimate the potential of the world's forests to store carbon.
14:47They break the planet down into millions of pixels and input data from field scientists.
14:54Each black dot indicates a place where someone has measured biomass and carbon storage in that
14:59location.
15:00There's about 1.2 million data points where someone stood on the ground evaluating the
15:05state of that forest.
15:06For areas without field data, they use satellite imagery and AI machine learning to fill in
15:14the gaps.
15:15But to fully estimate how much carbon forests can capture, they need to consider more than
15:23just trees.
15:25We need to include the fungi, the bacteria, the animals, and then start to predict the global
15:31pattern.
15:36In forests, carbon flows beyond the trees into the entangled underworld of fungi.
15:44I like the rain because this is the time of the mushrooms.
15:58Biologist Francis Martin has studied forest fungi for decades.
16:03When mushrooms begin to emerge in the fall, he couldn't be happier.
16:07I really like walking in the woods picking mushrooms because mushrooms are very beautiful organisms.
16:16Wow, it looks like the porcini, a very tasty mushroom, a great mushroom.
16:27This mushroom, it's likely the death cap.
16:31If you eat a piece of that cap, you are dead.
16:36So please avoid to have that one for lunch.
16:40Wow, magnificent, the king of the forest, the iconic mushroom, the fly agaric.
16:54If you peel the cap of the fly agaric, and if you dry it, you smoke it or you eat it, and
17:01then it's full of psychedelic compounds.
17:05I should confess that I never dare to taste it.
17:08I should, before I die.
17:10I prefer Burgundy wine, or even better Chablis.
17:15What you see there is only the tip of the iceberg, only maybe five, ten percent of the mass of
17:22the mushroom.
17:23The real mushroom, the most active part of the mushroom is underground, making a long
17:30a long filament of cells called the mycelium.
17:35It's like a, it's like a web, you know, it's like a web going beneath our feet and connecting
17:43to the trees.
17:45A single handful of soil can contain miles of fungal threads that form an intricate network.
17:55Fungi are not plants, they don't use photosynthesis to grow, but they do need carbon.
18:05So fungi like this have evolved to connect to tree roots and take carbon in the form of
18:10sugars from the tree.
18:14In return, the fungi give minerals and water to the tree.
18:20The tree will provide sugars to the network.
18:26And this network will use the sugars to fruit and make this beautiful mushroom.
18:36Inside the gills of the mushroom, millions of tiny spores form.
18:42These reproductive seeds are carried away by wind, rain or insects to begin new fungal networks
18:50elsewhere in the forest.
18:53I can feel the mycelium beneath our teeth and are just crawling, full of life and trying to
19:05emerge.
19:08More than 80% of all plant species form partnerships with the underground mycelium.
19:20By providing nutrients and water, fungi support the growth of the forest.
19:34In Amsterdam, a team of biologists and physicists is studying how fungi and plants exchange carbon
19:41and minerals.
19:44They grow plant roots and fungi in petri dishes and examine their interactions under a microscope.
19:58They take an image for every petri plate every two hours so that we can see how the fungi is actually growing.
20:08The images show the fungi growing hundreds of threads that simultaneously search for new sources of carbon.
20:19These patterns are just a few inches across.
20:24Imagine the scale of the networks running through an entire forest.
20:28We can see the highways but we can also look into the traffic inside those highways.
20:38I can move to florescence.
20:45This is live, we're watching the fungi move nutrients right now, right here, and that gives us a whole new way of studying fungal behavior.
20:57They are discovering that in the partnerships with plants and trees, fungi are highly manipulative power brokers.
21:06The fungi have evolved strategies to be able to identify the plants that give them the most carbon in return for phosphorus and nitrogen.
21:19They'll actually hoard it in their network until the price of phosphorus and nitrogen go up, until the plant really needs it, and then they'll get more carbon in return.
21:30Or they'll move it across to a totally different part of the network where the root is giving more carbon in exchange because it needs more nitrogen and phosphorus.
21:41And for hundreds of millions of years, these fungi have been evolving strategies to really maximize their trade with plants.
21:54An estimated 3.5 billion metric tons of carbon moves from plants into fungal networks every year.
22:04And forests with healthy fungi will ultimately store more carbon than plantations that lack them.
22:10Tom Crowther began his career studying fungi, examining how samples grow and interact in small dishes at Yale University.
22:26When you put two fungi together in a petri dish, what tends to happen is one often outcompetes the other.
22:33But when you add a third fungus, quite often it will fight with the one that's winning, so the other one can survive.
22:39As you add a fourth and then a fifth fungus to the system, the more likely you are to find stability so that they all survive.
22:46We call them microcosms, but they are microcosms of the real world.
22:51They're a glimpse into what's happening in nature. Diversity begets diversity.
22:57Tom was captivated by this balance he saw when lots of species live in close proximity.
23:04His findings on fungal interactions were good science, but the focus of his work was narrow.
23:11I was definitely too scared to step outside of my field, and I was, you know, it's safer to stay in your petri dish.
23:18Then one day, something changed Tom's outlook on the world.
23:25So I'm a postdoc in Yale, and my friends come over for a holiday, and we jumped off this rock.
23:31It's pretty high. And as I entered the water, my face got slapped by the water, and I just climbed onto the boat and immediately went to sleep.
23:41And then for the next few days, I was just weird. I was just like walking into walls and just knocking over tables.
23:50And the doctor did the CT scan, and I was waiting in his office for him to come back, and he just came in holding a neck brace.
23:57And he just went, right, stay still. Don't move at all. Put it around my neck and was like, the ambulance is coming.
24:05You've had a very serious stroke. There was a hole in my brain.
24:10I went into a pretty serious depression, and it was just a long, long, dark journey after that.
24:19The stroke was bad. The depression was way worse.
24:26I'd always loved my petri dishes, but I'd always dreamed of going bigger, but I was too scared.
24:32Suddenly, after this period with the stroke and the depression, that was no longer a real fear.
24:38You've only got one life. You may as well go for it.
24:42Emboldened by his stroke, within six months, Tom's petri dish became the entire planet.
24:52Now he sought the answer to a simple but big question. How many trees are there on Earth?
25:00So along with his Yale roommate, Greg Hintler, he began to gather information.
25:07We started asking people, ecologists around the world, how many trees are in your patch of forest?
25:13And once we had enough data, we could start to see like a global perspective.
25:19We were pretty astonished to find that, we're not talking about millions or billions, there was actually three trillion trees on the planet.
25:27And that blew our minds. It was, you know, this first glimpse into the immense scale of this system.
25:35Tom's big data approach to ecology had revealed that there are many times more trees on Earth than stars in our galaxy.
25:47Trees are important carbon capture machines.
25:51But there's another part of the forest that plays a critical role, and Tom is eager to track its power.
25:58Right, let's see what we can see under here.
26:23What's that? That's a root.
26:38This is perhaps the most important of all animals. It's an earthworm.
26:44But if you really want to insult someone, you call them a worm.
26:48It's the most terrible insult to worms because of the tremendous work that worms do in terms of building soil and maintaining its fertility.
27:03Soil is a biological structure.
27:05It's built by the organisms that live in it, just like a coral reef.
27:10And most of the organic carbon in the soil takes the form of the glue used by creatures to stick the soil together.
27:23This is a baby earwig.
27:25Might not look like very much, but this is one of the giants of the soil.
27:28This is like an elephant or a rhino or a hippo, because the great majority of what you find is really, really tiny.
27:35There's a centipede here. There we go.
27:38This is one of the big predators of the soil.
27:41Look how fast it moves.
27:43Ooh, they're like lions or tigers.
27:48I love soil. You might have guessed.
27:51More than half of all the species on earth are thought to live in the soil.
27:58A little fly larva.
28:01Little tiny woodlows.
28:04Most are too small to see with the naked eye.
28:10But powerful microscopes reveal the diversity of these remarkable creatures.
28:16At the smallest scales, microorganisms like bacteria exist in close partnership with trees and plants.
28:35One of the most amazing revelations in any science in the past few years is that plants can talk.
28:42And plants can talk in a very rich and complex language.
28:48It's a chemical language.
28:50And what happens in the spring when roots are pushing through the soil, the little root hairs are growing,
28:56is that they will release very, very complex chemicals whose purpose is to speak to just one or two of the hundreds of thousands of species of microbes which might be in that region of soil.
29:13Most of those microbes won't necessarily do the plant any good.
29:17Some are positively harmful, but some are extremely beneficial.
29:20And it's those ones they want to wake up.
29:25The plant floods those bacteria with sugar.
29:29And amazingly, between 10 and 40% of all the sugars that plants make through photosynthesis is poured into the soil.
29:38And at first sight it looks like pouring money down the drain.
29:41They go to this massive effort to make all this sugar out of sunlight and carbon dioxide and water and then they go and dump it in the soil.
29:49What's going on?
29:50They're feeding the microbes.
29:51In the soil around their roots, trees and plants cultivate microbes to break down the minerals they need and to fight off harmful bacteria.
30:05Just as we rely on microbes in our guts to digest our food, plants also need a healthy microbiome, the rhizosphere that surrounds their roots.
30:17The rhizosphere might lie outside the plant, but it's the plant's external gut.
30:26And to make this comparison even spookier, of the thousand or so phyla of bacteria, the major groups, there are four that dominate in the rhizosphere.
30:39And there are four that dominate in the human gut.
30:43And they're the same four.
30:44There's soil ecologists in every location you can ever think of.
30:53And by pulling together that data, we get a picture of the soil carbon storage and then that we use to scale those forest estimates.
31:00Tom's model predicts that an extra 45 billion tons of carbon could be stored in dead wood and leaf litter and an additional nearly 35 billion tons in the soil itself.
31:15But the soil's microscopic creatures are not the only animals that shape the flow of carbon through the forest.
31:24To maintain a balanced ecosystem, a healthy forest needs insects.
31:31In Booty National Park in Southeast Australia, Tanya Lattie is sweeping the forest for bugs.
31:40Oh, she's so pretty.
31:41This is a praying mantis and she's an ambush predator so she waits till she sees some food nearby and then she'll just reach out with those two big front legs to capture her prey.
32:05Jumping spiders are also predators so they'll eat anything they can jump on that's smaller than themselves and they have some of the best vision.
32:14Grasshoppers are herbivores so they eat plant material, but they're really important as a source of protein and fats for many of the animals in this forest will eat a big insect like this.
32:31Oh, landed on the net.
32:38Animals like mantises and spiders eat smaller insects that if left unchecked could damage trees and plants in the forest.
32:47In turn, these larger bugs feed birds and small mammals that help spread seeds and support the forest in other ways.
32:5670% of all animal species are actually insects, so they're the vast majority of biodiversity.
33:03Insects are our primary pollinators, they are our pest control, they're important for recycling matter back into the ground.
33:11A forest like this one could not exist without insects.
33:14In the tree canopy, larger creatures play an important role too.
33:28In the Atlantic forest of Brazil, ecologist Mauro Galletti is on the trail of marikis.
33:45Marikis are one of the largest primates in the Americas.
33:49But they're also one of the most endangered.
33:56They're rarely seen.
34:05The core of the marikis.
34:08That's the marikis.
34:10Amazing.
34:11Yeah, right here.
34:12Yeah, right here.
34:13You see?
34:14Right here.
34:16Right here.
34:17The one crossing here.
34:19Yeah, over there.
34:21Wow.
34:23Wow, you see?
34:24Different individuals, adults, females, juveniles.
34:30Not every day they just see marikis like this, so close.
34:35They're super rare.
34:36Their populations are very small.
34:37They only occur here nowhere else in the world around there.
34:42You see?
34:43Yeah, that's a baby.
34:49They are pooping on us.
34:56So when they wake up, they poop and they disperse a lot of seeds.
35:01And then they move to another tree and another tree.
35:04And then they, you know, keep doing their job.
35:07That's planting the forest.
35:12Animals like mariki are essential for the survival of large trees in the forest.
35:19As here in the tropics, trees need animals to spread their seeds.
35:24This is a tree that is fruiting now.
35:29It's a large tree.
35:31And when it's fruiting, all the, all will drop.
35:34And you can see the fruits here.
35:36And open, you see?
35:38They're dropping.
35:39Insects or fungi or rodents come to congregate here to eat the seeds that's inside this juicy pulp here.
35:52And these seeds, they have to compete with the mother plant for nutrients and light.
35:57So they won't germinate.
36:01What the plant really needs, someone to swallow the whole thing and take away and plant somewhere else, not close to the parent tree.
36:10The animals are the gardeners of the forest.
36:17Mauro's research has shown that in this forest, 90% of the trees rely on animals to move their seeds in order to reproduce.
36:28The largest trees, that store the most carbon, typically have the biggest seeds and need animals like mariki to disperse them.
36:44Woohoo!
36:46Look what we have here.
36:49Mariki poop.
36:51It is fresh and full of seeds.
36:55Can you see all the seeds here?
36:56Oh, look at this big seed here.
36:59Wow, there's one that is really big.
37:01You see?
37:03So this big seed will make a big tree, which stores more carbon.
37:08Like you have here, there's one particular example.
37:13So you have the mariki poop, the seed, and you have the seedling.
37:18You never imagined that could become a giant tree that stores a lot of carbon.
37:27This is the future of the forest.
37:38The absence of just one animal group, like birds, can reduce the potential of forests to store carbon by around 38%.
37:46As forests decrease in size, these species are disappearing.
37:56And that's due to another animal that's had more influence in the shaping of modern forests than any other.
38:03In the highlands of southern Costa Rica, Rebecca Cole witnessed the dramatic loss of old-growth forests.
38:19As a young girl, she saw her parents clear the forest for farmland.
38:24What happened in this landscape was, when my parents came in, it was a frontier.
38:31It was upwards of 90% forest cover.
38:34People thought that nature was sort of endless, it was an endless resource, and, you know, learned that it's very finite.
38:40People started clearing the land.
38:45It's very steep, it rains a lot here.
38:48All of the nutrients are in the vegetation.
38:49When you cut it down, it just very quickly leaves very impoverished soil behind.
38:55So the land became degraded very quickly, and it was very difficult to do any sort of agriculture on.
39:02I got into restoration ecology to try to bring back the forest, because my parents were some of the people that chopped it down.
39:19My dad's trajectory was coming in and thinking we were going to conquer nature.
39:24He wrote a whole book that was essentially an apology.
39:43Rebecca is now trying to restore forests in areas cleared by her parents.
39:48In some fields, it's virtually impossible for trees to grow again without a helping hand.
39:57This is one of these introduced pasture grasses that just takes over big areas and doesn't let much else grow.
40:07They're just very aggressive.
40:09You just don't get any natural regeneration in areas that are covered with this type of grass.
40:13I'll go deeper into the weeds.
40:19To give trees a fighting chance, Rebecca plants islands of hardy species like guaba amidst the sea of grasses.
40:29This is one of my favorite species for restoration.
40:33It's a fast-growing tree.
40:35Once it gets up above the grass, it just sends its branches out, it creates a lot of shade, drops a lot of leaf litter,
40:40and creates a wonderful safe site for seedlings to grow.
40:46This little seedling is a couple of years old.
40:48We've got a couple other ones around us that are just starting to poke out over the top of the grass.
40:53Birds will see this as a perching structure, and they'll perch.
40:56Hopefully they'll poop, they'll leave seeds here, and those seeds will have a better chance of germinating and growing than they will out in that ocean of grass.
41:04The research team charts the progress as the tree islands expand outwards.
41:18They monitor the birds and bats that visit, and collect samples of the tree seeds that are dropped.
41:24By identifying individual seeds, the team can find out which tree species are spreading well, and which are struggling.
41:35The goal is to figure out the best methods to speed forest regeneration in degraded areas across the tropics.
41:43Planting small islands of the right trees could help create the ancient forests of the future without the need for mass tree planting.
41:54But finding suitable land for large-scale forest restoration that doesn't destroy people's livelihoods can be a challenge.
42:03Tom and Li Dong exclude current farmland and urban areas from their model.
42:12Their main focus is on the potential of existing forests and land outside of human use.
42:18In between them, it looks sort of like that.
42:20They are almost ready to publish their study.
42:23I think it's looking good. I think after four years of eternally adapting these models, I think I'm feeling pretty confident.
42:29Five years. Five years, ten million models and hundreds of co-authors later, I think we're looking pretty good.
42:42As the publication date approaches, Tom prepares to face the media, hoping to avoid another backlash.
42:51In an online press conference, he announces how much carbon their model predicts forests could store.
42:58So yeah, thank you all for joining. For a little bit of background information, for the last few years, a large network of ecologists have been trying to build this integrated global forest assessment.
43:11By working together, the average effect across all of those models is around 226 gigatons of carbon.
43:17The average forest today is only around 30% of its full maturity because we've stripped out trees and damaged the underlying ecosystem.
43:28So most of the potential lies in restoring existing forest to full health and the rest by regrowing lost forests.
43:37The team estimates that 226 billion tons of carbon could be captured, almost a third of all the carbon emitted since the Industrial Revolution.
43:50But forests won't help fix our climate unless we also dramatically cut our emissions.
43:56That is a really exciting opportunity to achieve massive scale carbon capture simply by protecting the ecosystems that we have.
44:06There cannot be a choice between nature and decarbonizing.
44:11We absolutely must take steps to achieving both simultaneously.
44:15Now Tom wants to get the message to world leaders.
44:30At the United Nations climate meeting in Dubai, he seizes the opportunity to address them on the biggest of stages, at the COP summit.
44:38Thank you so much. The link between nature and climate is so critical. The conservation of existing forests is our most powerful carbon drawdown tool, allowing those ecosystems to regenerate.
44:53Then on top of that, the recovery of diverse ecosystems, integrated landscapes can achieve the remainder.
45:00This cannot be achieved though through mass plantations because the power of nature is in its complexity.
45:06Which means that diverse forests store more than twice as much carbon as monoculture plantations would.
45:15And we cannot be achieving this without emissions cuts.
45:21There can be no choice between cutting emissions and nature because we categorically need both.
45:27It's only when nature and people thrive together that we will have long-term carbon capture as a byproduct.
45:34Thank you very much.
45:41Tom's message to preserve old forests is being heard.
45:49But what is their current health?
45:54NASA collects data from sites on the ground.
45:57These are billions of laser points that were collected in the field with an instrument called the terrestrial laser scanner to essentially make really detailed measurements of the forest composition and forest structure.
46:12Measurements like this support Tom's findings that we need to preserve old-growth forests because they store more carbon than plantations.
46:25But satellite imagery shows we're losing ancient forests.
46:29Over 15,000 square miles is felled each year, mainly for cattle grazing and crop growing.
46:38So what's the answer?
46:44Can we still have the things we need, like food and timber, while restoring the planet's ancient forests?
46:51Many of us live today in cities, which in terms of ecological footprint can be a really good thing.
47:05But that does mean that we feel disconnected.
47:07We don't see the way that our food is coming from the land.
47:10It becomes invisible to us.
47:12Robin Wall Kimmerer believes that indigenous practices show that you can take from nature without damaging the ecosystem.
47:24In Potawatomi ways of thinking, we're always said, well, how do I give back in return for what I've been given?
47:31We have a worldview that says that the forest are our relatives, they are our providers, they take care of us, and we have to take care of them.
47:45But we also need wood for our homes, and we need firewood, and we need berries.
47:50So the ethic is not that you don't take, because we have to take.
47:56Only take what you need.
47:57Be in reciprocity, give back for what you've taken.
48:02Use a technology which minimizes harm.
48:06Whether we're taking it directly from a forest, or whether we're going to the corner store, it's still all coming from the earth.
48:18Tom's research offers a practical way to help people connect with forests.
48:23Anyone can access his online maps to check an area's natural potential.
48:30You can now zoom around the world, you can draw around that location, and automatically gain insights.
48:37We can see about the carbon storage that's being generated in all those ecosystems.
48:41And what's really cool, we've had hundreds of thousands of local farmers, indigenous communities, local populations, drawing around their areas on the map.
48:52And they get ecological information, but they then also gain visibility.
48:56So now, we can all see them.
48:58One of the examples I often use, where is it, is in Ethiopia, it's Dester's farm.
49:04You can see from the surrounding area, there's a massive agricultural footprint of coffee production.
49:10But as we zoom into Dester's, we can see it's an absolutely intact rainforest.
49:14And that's because he's planting the coffee trees underneath the canopy, which is trapping water and nutrients and supporting those trees so they grow well.
49:21And with tools like this, you can now start to see where you're getting your coffee from.
49:30You can identify the footprint that it's having on biodiversity and carbon and water.
49:36And that means you have the power to then choose a positive product rather than a negative one.
49:41So with every little decision, you and I are changing the world.
49:45We're all contributing to global restoration.
50:10This is the place I come every weekend.
50:11I feel like my social life has been replaced by forest.
50:24Five years ago, it was no one mentioned nature when it comes to climate change.
50:29Four years ago, everyone was just pledging how many trees they can plant.
50:32Now, everyone's committing to how much indigenous land they can protect or how many rights of farmers that they can empower.
50:37It's unbelievable.
50:38It feels like momentum is now building.
50:47We don't know anything about the forest. We're just starting.
50:51There's a lot of pessimism, climate change, biodiversity laws.
50:56But I think never ever in the human history there's so many people interested in saving animals, saving plants, doing ecology.
51:07I lose a lot of sleep over the challenges that we're facing, but it's so much easier to do something about it than it is to do nothing.
51:17Hopefully, that'll make a difference.
51:18Hopefully, that'll make a difference.
51:20There's a huge number of species which remain unknown, hundreds of species which are very critical for the life of planet Earth.
51:32This need to be active to support the life, the trees, the plants, and probably mankind.
51:39We're in a whole new era of science right now. I get goosebumps just thinking about it.
51:48We used to categorize things, but now we're in an era that studies interactions.
51:53It's not going to be about just one solution like planting trees.
51:58It's going to be about understanding the interactions between all organisms in an ecosystem and saving those interactions.
52:05Thank you for listening.
52:35Transcription by CastingWords
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