A Trillion Trees: Restoring Our Forests by Trusting in Nature

By Fred Pearce

• Controversial take on tree planting: Pearce argues that tree planting is problematic and that forests should be given space and time to heal on their own.


• We are all connected by trees: We often think of saving only our local trees. Pearce shows that we must think globally; humans depend on forests everywhere to keep our planet cool, breathable, and livable. 


• Indigenous knowledge: Pearce interviews Indigenous peoples who live in and depend on the forests he writes about and shares their knowledge with their consent.


• Adventure travel: Pearce takes readers on an adventure to visit some of the most spectacular and unusual forests in the world.


• Books about tree and plant intelligence are top sellers: The Hidden Life of Trees, Braiding Sweetgrass +The Overstory together sold nearly half a million copies in 2020.


• Award-winning environmental science writer: Pearce has authored more than a dozen books and has won awards for his writings, which range in subject matter from the water crisis to consumerism and radioactive waste.

• Language: English
• Publisher: Greystone Books
• Release date: Apr 26, 2022
• ISBN: 9781771649414

Book preview

Cover: A blurb from Ben Rawlence, author of City of Thorns, reads, “A vision for how we can, and must, reforest the world. Essential reading for the twenty-first century.” Against a background of tree rings are dark red and green silhouettes of trees.Title page: Fred Pearce. A Trillion Trees. Restoring Our Forests by Trusting in Nature. The Greystone Books logo is at the bottom of the page.

To the memories of Don Hinrichsen and Conrad Gorinsky, pioneers both

Contents

Map: A Forest Journey

Introduction: Myth and Magic

PART I

WEATHER MAKERS

1. Trees Are Cool

Stomata, Transpiration and a Planet Transformed

2. Flying Rivers

Chasing the Rain and Mapping a New Hydrology

3. Forests’ Breath

Sniffing the Air and Shooting the Breeze

4. In Tanguro

Tipping Points in Soybean Fields Foreshadow Crisis in the Amazon

5. Fires in the Forest

Nature’s Way of Starting Over

PART II

FROM PARADISE TO PLUNDER

6. Lost Worlds

Pre-Columbian Cities That Gardened the Rainforests

7. The Woodchopper’s Ball

Post-Columbian Pillage and Roads to Ruin

8. Logged Out

Well, Almost . . . Three Decades in Borneo

9. Consuming the Forests

Logs of War and a New Green Plunder

10. No-Man’s-Land

Cattle Kingdoms and the Tyranny of Global Commodities

11. Taking Stock

Phantom Forests and Debunking Forest Demonology

PART III

REWILDING

12. From Stumps and Ashes

America’s Forest Renaissance

13. The Strange Regreening of Europe

Acid Rain to a New Green Deal

14. Forest Transition

How More and More Nations Are Restoring Their Forests

15. To Plant or Not to Plant

When Trees Become Part of the Problem

16. Let Them Grow

Only Nature Can Plant a Trillion Trees

17. Agroforests

Farmers as Part of the Solution

PART IV

FOREST COMMONS

18. Indigenous Defenders

Why Tribes Do Conservation Better Than Conservationists

19. Community Forests

A Triumph of the Commons

20. African Landscapes

Taking Back Control

Postscript: Back Home

Acknowledgments

Notes

Further Reading

Index

Introduction

Myth and Magic

MY FIRST REAL EXPERIENCE of the wonder of tropical forests came in the Andean Mountains of Ecuador. It had been a long drive from Quito and evening was drawing on as we climbed into forests shrouded in clouds—clouds whose coverage was so extensive and permanent that no cartographers had ever mapped the terrain, and no satellites had ever observed the surface beneath. Breathing the sopping-wet air and peering into the gloom, I could understand why people occasionally showed up here believing that the trees hid an El Dorado of gold buried by the Inca half a millennium ago.

But I hadn’t come for gold. Walking the next morning into the eternal mists above the valley town of Baños, I met Lou Jost. An American botanical explorer, he had come here to uncover his own El Dorado: a biological trove of orchids found nowhere else. He said his discoveries were changing our understanding of how and why plants evolve to create species that are unique to particular places, and why forests contain so much of the world’s biodiversity.

When I met him, Jost had already spent six years exploring the ridges around Baños. He operated alone, without the help of any academic body, having given up work as a quantum physicist in the US to pursue his dream. He said he found scouring the cloud forests for orchids more mind-expanding than the wonders of the universe. Quantum physics offered nothing you could touch and feel, he told me. But as soon as I visited a cloud forest, I was hooked. On the wet, sunless forest floor, species of orchids have evolved in the thin air with flowers so fragile that they would collapse anywhere else. He had already discovered ninety previously unknown orchids, and believed there were more here than anywhere else in the world. He had become an artist too, drawing and painting his discoveries.1

The Pastaza valley, where Baños is situated, is the deepest and straightest valley in the eastern Andes, draining down into the vast basin of the Amazon River to the east. Despite being virtually on the equator, it is bone-chillingly cold and wet, and riddled with cliffs and ravines that are all the more dangerous in the permanent cloud. Not many people pass this way. The infrequent trails are mostly made by the mountain tapirs and spectacled bears.

The outside world intervenes, nonetheless. Every day a wind blows in from the Amazon rainforest, bringing huge volumes of moisture that condenses to form the near-permanent clouds. Each ridge catches the winds a little differently and has a different micro-climate, said Jost. Each species seems to specialize in a particular combination of rain, mist, wind and temperature. Some species grow by the thousand on top of a single ridge, but disappear just a few feet below and are found nowhere else.

The only way to discover the botanical secrets of these forests is to walk them all, Jost told me. Many of the hills have never been visited by scientists. Well, almost never. Jost came originally to follow in the footsteps of his hero, English botanist Richard Spruce, who trekked through the Pastaza valley in the 1850s, discovering ferns and liverworts that have never been seen since. The valley is comparable to Ecuador’s other, more famous biological treasure house, the Galápagos Islands. On one red-letter day, Jost found four new species in a single patch of moss, raising the number of known orchid species of the genus Teagueia from six to ten. Since then, he has identified more of the distinctive long-creeping orchids here. One, Teagueia jostii, bears his name.

Jost’s orchid collection had become a life-consuming passion. His apartment in Baños was strewn with plant samples. A tiny rooftop greenhouse grew plants collected on past expeditions. Many had only opened their petals under his tender care. You have to know what you are looking for when you go orchid hunting, he says. The flowers are only a few millimeters across and usually hide under the leaves. Often the plants are not in flower. If I spot what I think is a new species, I can often only be sure when I bring it back here to wait for the flower to appear.

Their survival in Jost’s apartment looked precarious. He kept the greenhouse air mountain-cool with an electric fan, which depended on the town’s fitful power supply. As a backup, he had a passive air conditioner that drew in air over permanently wet tiles. There was an ingenious device to maintain humidity, using a paperweight balance. When a packet of plant stalks on the balance became too dry, it lost weight and the balance shifted, switching on a humidifier. Once moist again, it switched the humidifier off. It’s not perfect. But it means I can go away on plant-collecting expeditions and be fairly sure my specimens will still be alive when I return, he said.

Can Jost’s wild orchid El Dorado survive? The value of the Baños cloud forests’ biological heritage is increasingly being acknowledged. In 2006, near a waterfall just down the valley from Baños, Jost and local officials erected a bust to commemorate Spruce’s journey there. Jost, a loner when I visited him, is becoming a celebrity himself. He now runs the EcoMinga Foundation, an NGO dedicated to protecting Ecuador’s upland ecosystems. In 2016, TV naturalist David Attenborough launched a film about Jost and the orchids of Baños.

Tourists are flocking to Baños too. Some come to kayak or go white-water rafting on the Pastaza River as it cascades down towards the Amazon. Others are scientists and nature buffs. Their enthusiasm is changing local perceptions about the cloud forests. "In the past, the campesinos saw nature and the environment as a symbol of their poverty. But scientists coming here have introduced them to the idea that it is something to be proud of, said Patricia Guevara, a former vice-mayor of Baños who spotted the trend early and set up an eco-lodge in the valley. Jost too sees the growing interest as good news. These kinds of tourists bring money and fill hotels, but to keep them, you have to keep nature as well." He should know. He was a tourist once too, lured by the legend of Spruce and, staying on, captivated by the magic of the orchids of the cloud forests.

THE WORLD’S GREAT FORESTS are awe-inspiring places, but some of my most memorable forest experiences have happened on my own doorstep. I remember, at the age of about seven, getting lost with a friend in a wood near my home on the North Downs in Kent. It was a small wood, but we kept walking in circles. After an hour, the sun was setting. There seemed to be no way out. My friend said a plane had crashed here during the Battle of Britain. There was a big hole that looked like the impact crater. We wondered if the ghost of the pilot might still be there. We were thoroughly spooked. It was probably the first time that I had contemplated my own mortality.

Forests have always transfixed the human imagination. Our fairy tales are full of cautionary tales about these dank, mysterious places. Little Red Riding Hood was waylaid in the woods by a big bad wolf as she delivered provisions to her grandmother. Hansel and Gretel lost their way and were kidnapped far from home by a cannibalistic witch. The fair maid Rapunzel was incarcerated in a tower deep in a wood. Even modern tales often invoke forests for their imagery of mystery, evil and dread. Think The Lord of the Rings, Where the Wild Things Are and The Blair Witch Project. Woods are where bodies are buried, darkness pervades and evil lurks. Swiss psychoanalyst Carl Jung called their hold on us primordial.

But there is wonder too. I also remember childhood walks in the cool air and dappled light of Wealden woods. As an adult, I return repeatedly to the ancient yews of Kingley Bottom in southern England, Europe’s largest and oldest yew forest. Surrounded by grassy downland and overlooked by Bronze Age burial mounds, it speaks to me of the permanence of humans in natural landscapes.

Most of the world’s religions use trees as symbols of life. The Koran features a tree of immortality, where the souls of righteous people live forever. Christians and Jews share a tree of knowledge, the centerpiece of the story of the fall of mankind in the Garden of Eden. The branches on the Buddhists’ tree of wisdom, a fig growing in the Mahabodhi Temple in Bihar, India, are the source of the four rivers of life. Such reverence is not surprising. As British naturalist Richard Mabey points out in his book The Cabaret of Plants, trees are capable of outliving not just individual humans but whole civilizations. 2

Trees have helped shape civilizations too, inspiring a colonial lust to explore and tame. When the early European explorers encountered the rainforests of the tropics, their imaginations were infected with both fear and excitement. From Francisco de Ore-llana, the first European to travel the length of the Amazon, to Sir Walter Raleigh, the courtier to Queen Elizabeth who twice sailed up the Orinoco, the Spaniards and English for centuries went to South America in search of El Dorado, a city hidden in the jungle that they believed to be full of gold.

There was awe. Raleigh called the forests he sailed through a country that hath yet her maidenhead, never sacked, turned nor wrought.3 Two centuries on, Prussian scientist-explorer Alexander von Humboldt found an inexhaustible treasure trove . . . just like paradise. The rainforests were places where, he wrote, every object declares the grandeur of the power, the tenderness of nature, from the boa constrictor which can swallow a horse, down to the hummingbird balancing itself on the chalice of a flower. He saw their inhabitants in similar terms: an infant society that enjoyed pure and perpetual felicity.4

Those explorers also found a world so alien to them that they returned home telling tales of inexplicable horror. Many recounted stories of an Amazonian tribe whose members had no heads, but eyes in their shoulders and mouths on their breasts, and of warrior women who procured and discarded slave men at will. In Africa, the British explorer Henry Morton Stanley called the rainforest a murderous world full of filthy vulturous ghouls. 5

Some nineteenth-century explorers found time to observe more dispassionately. Jost’s hero Richard Spruce, a shy, sickly math teacher from Yorkshire in England, spent fifteen years collecting ferns, mosses, lichens and liverworts in the Amazon basin. In his notebooks, he analyzed a tendency to gigantism in the jungle, with bird-eating spiders, eight-inch slugs, seven-inch butterflies and goliath beetles. But even he succumbed to the almost psychedelic intensity of this world, summed up in his sampling of the botanical hallucinogen Ayahuasca, known as the vine of the soul. First, it gave him visions of beautiful lakes, woods laden with fruit, birds of brilliant plumage. Then paradise became purgatory, as his body turned deadly pale, trembling in every limb, bursting with perspiration and seeming possessed with reckless fury. 6

Even today, for those who don’t dwell in them, forests remain somehow other. German filmmaker Werner Herzog, in Burden of Dreams, saw rainforests as places of overwhelming misery and overwhelming fornication, overwhelming growth and overwhelming lack of order. 7 Forests are places that still seem to exist apart from global events, their occupants sometimes losing touch with reality. There are stories of Second World War combatants emerging from a jungle decades later, unaware that hostilities were over. A Russian family that fled Stalin’s purges in the 1930s was found forty years later, holed up in Siberian forests, unaware of Stalin’s death or even of the Second World War.8

These days we more often accentuate the positive. The new El Dorado is primarily biological. Fearful jungles are rebranded as bountiful rainforests, miracles of biodiversity where nature makes chemicals that can cure cancer. A sense of sheer wonder persists, even among our most eminent forest scientists. The biodiversity guru Edward Wilson calls rainforests timeless, immutable . . . the crucible of evolution.9 For climatologists they are the lungs of the planet.

Despite scientists’ attempts to discover the forests’ secrets, many mysteries remain. This book seeks to investigate some of them and help us see forests a little more clearly. One unheralded truth is that most of the world’s forests—even the largest and most remote—are not as old or as wild as we like to imagine. There may be some exceptions: perhaps a ridge or two in the cloud forests of Ecuador, or some remote portion of the vast northern forests of Siberia, or maybe even a fraction of the boggy peat-swamp forests of Southeast Asia could have escaped our attentions. But almost all forests are marked by extensive human occupation and alteration that are now imprinted in their ecology. No forest still hath her maidenhead.

Many of the wildest, apparently least-tamed forests are little more than overgrown gardens created by the ancestors of those who live in them today. That, I believe, has important lessons for how we should treat our forests and their inhabitants today. We may indulge our forest fantasies. Even so, we should remember they are at least as much human landscapes as pristine paradise.

For decades, I have been reporting on the importance of trees—for keeping us cool, preserving the planet’s species, maintaining rainfall, alleviating poverty and protecting Indigenous people. I have written too about who owns them, who uses them, who protects them and who trashes them. This book is an extension of that work. It is about the magic and mystery of trees and forests, about their defenders and plunderers, and why they matter for the planet and for all of us. Along the way, it will chart the extraordinary pace of the forests’ destruction, which peaked at the end of the twentieth century, but also explore where and why they are recovering. It will look forward to a great forest restoration in the coming decades, explain how it can happen and why it must.

It will also take you on a journey through the world’s forests—to the forty or more countries I have visited to enter forests and interview their inhabitants. To the cloud forests of the Ecuadorian Andes, which few outsiders have explored since Spruce, and the radioactive (but otherwise healthy) forests around Chernobyl in Ukraine; to the swamp forests of Indonesia and the community forests of the Himalayas; to the acid-rain-ravaged forests of central Europe and the pine forests in the American Deep South being cut to keep the lights on in Britain; to sacred groves in India and forests that funded war in Liberia; to the depths of the Amazon and the peak of Ascension Island’s Green Mountain in the middle of the Atlantic Ocean; to the vast larch and pine forests of Siberia and the multicolored magnificence of New England in the autumn.

In my travels, I have flown for hours over the hundreds of billions of trees in the Amazon, and got up close to the only tree on the windswept Falkland Islands—in the British governor’s garden. I have visited the remains of a largely unknown ancient forest civilization in Nigeria and the remarkable natural reforesting of the drought lands of the African Sahel. I have penetrated the weird thorn forests of the Paraguayan Chaco, under siege from Brazilian ranchers, and seen China’s attempts to turn back its deserts with trees. I have visited the front line of the palm oil invasion in Borneo and the desecration of Sumatra’s forests to keep paper in your printer. I have toured a forest on the edge of the Israeli desert that is perversely adding to global warming and climbed a gantry as high as the Eiffel Tower in the middle of the Amazon rainforest, erected so German scientists can sniff the breath of the planet’s lungs.

I have met Scottish crofters reforesting the Highlands and Indigenous tribes mapping their forests with GPS on their phones; a Russian nuclear physicist who believes that forests make the world’s winds and an English adventurer trying to prove her right in his back garden; a playboy bush pilot who showed the world that the Amazon forests water a flying river that makes rain; an Israeli who says planting a billion trees in the Sahara could make it as lush as the Amazon; a hired farmhand in Malaysia facing execution for assassinating a forest campaigner; and an American scientist in exile after being pilloried for suggesting that forests could sometimes be bad for the climate. Back home I reconnected with the gnarled yews of Kingley Bottom and the bluebell woods and colossal sweet chestnuts of nearby Burton Park. Each of these encounters with forests, and with those who know them best, has helped me understand the significance of trees for the continuation of our planet and of human life.

ABOUT HALF THE WORLD’S forests have gone since the dawn of civilization. What we have lost shames us as a species. The sound of chainsaws has replaced birdsong from the steppes of Russia to the backwoods of Australia. But what we have left is immensely precious. Almost a third of the planet’s land surface is still covered by around three trillion trees—more than all the stars in the Milky Way.10 They are home to more than half the world’s species. They cleanse air and water. They deliver fruits and nuts, rubber and timber, honey and medicines. They manage the water cycle, storing water in soil to maintain river flows and control floods. They control the climate too. They store as much carbon as humans have emitted into the atmosphere since the start of the Industrial Revolution. And each day, every tree pumps around thirteen gallons of water into the atmosphere from quintillions of tiny pores on their leaves, keeping the atmosphere moist and cool.

The good news is that the great shaving of our planet may be coming to a close. In some countries, humans are putting back trees. Sometimes by planting. China and India, the world’s two most populous nations, have found room to seed more forests. From Costa Rica to Nepal, there are similar stories. However, often—and just as importantly—we are giving natural forests room to recover. For the other great unheralded truth about our forests is that they are far from being passive victims of our assaults. Everywhere they fight back to restore their domain.

For several years, there has been a growing campaign to restore an additional trillion trees by, say, the end of this century, to help fight climate change, restore ecosystems and halt species extinctions. The idea is both beguiling and doable. Recent research says there is room—much of it on formerly forested lands that have not been turned into farms or cities or mines or anything else. Some say we could plant up parts of our great grasslands too. Deserts even.

I buy the ambition. A planet with a trillion more trees would be a much better place. My problem is not with the ambition of a trillion more trees; it is with the word planting. It implies, indeed requires, a global industry, taking over farms and former forest land, often riding roughshod over local rights, in the name of reforestation. And it would be costly: almost $400 billion a year for the next thirty years, according to one assessment—a cool $12 trillion.11 If we want a trillion more trees on our planet, as I believe we should, the last thing we need is a big planet-wide project to go out and plant them. It would be bad for people, bad for forests and in the end bad for the planet too. It would also be entirely unnecessary. We don’t have to do the planting. We shouldn’t do the planting. Nature will mostly do it for us. And she will do it better. If we stand back and give them room, forests will regrow.

Europe has a third more trees today than it had in 1900. So does North America. Most of them were not planted. Our planet as a whole has more trees than it did a decade ago. The great forest restoration may already be underway. Take a look at Niger, one of the world’s most arid, poorest and hungriest nations. Farmers there have encouraged buried roots to repopulate their desiccated fields and been rewarded with better grain yields, richer soils and healthier families. A region once thought to be succumbing to the advancing Sahara is now greened, wetted and cooled by 200 million extra trees. If they can restore natural treescapes there, it can be done almost anywhere.

There will be no return to primeval wilderness. The world has changed too much for that, and in truth it is many centuries since there have been significant numbers of pristine forests. That may sound dispiriting, but actually it should give us hope. It should not extinguish the magic, for it shows that nature can everywhere be resilient and resurgent. The great forests have recovered from human activity before. They can again.

From the journeys I have made through the world’s forested, deforested—and reforested—landscapes, the lesson seems to be consistent: we can put our trowels and bulldozers away. Pack up the seed nurseries and put our money back in our pockets. In most places, to restore the world’s forests we need to do just two things: ensure that ownership of the world’s forests is vested in the people who live in them, and give nature room. Rewilding the Earth does not mean replanting; it means the exact opposite.

THIS BOOK IS DIVIDED into four parts. In the first, Weather Makers, I explore some new and extraordinary science about how fundamental forests are to our planet’s life-support systems, and how trees have literally made the environment in which they—and we—prosper. This is not just to do with the carbon they store to curb the greenhouse effect of global warming, important though that is. It is also to do with how forests make the rain that sustains them, and how the forests’ chemical breath helps make clouds and may even make the winds. It reveals how these systems are self-sustaining. The forests make the rain and the rain maintains the forests—though only up to a point. Beyond that tipping point, forests may rapidly degrade and disappear. We visit the front line where that tipping point may be being breached right now in the Amazon rainforests.

Part Two, From Paradise to Plunder, asks how we got to this tipping point. Once, humanity had a good working relationship with forests. We mostly harvested them without destroying them. Yet in more recent times, we have forgotten how to do that, and instead felled half our forests and pushed the world towards a climatic Armageddon. During thirty years of environmental reporting I have seen the carnage created by soybean farming, palm oil plantations and cattle ranchers. But there is good news even here. The history of human occupation of our forests—including those we today regard as pristine—shows that deforestation need not be forever. Provided that they are not pushed too far, forests can and do recover from our depredations. Much of the Amazon is actually regrowth from clearance by former civilizations. So we need to take stock rather than be defeatist. Give them the chance and many forests can return.

In Part Three, Rewilding, we discover that forest recovery is already happening. Europe and North America are much more forested than they were a hundred and fifty years ago, or a hundred years ago, or even fifty years ago. Sometimes those forests are not much like the old ones—especially where they have been planted. In most places, however, nature is already reclaiming her own, spreading new forests across abandoned fields. From the downs of southern England to the Russian steppes, from New England to the Deep South, we explore this brave new world of natural forest restoration and the surprising return of trees to farms. This rewilding is surely the new environmental agenda for the twenty-first century.

And, as I uncover in the final part, Forest Commons, this return of the trees goes with the grain of an emerging community-centered approach to nature, forests and the land. We are relearning what we should never have forgotten: that forest people—whether Indigenous Amazonians or Nepalese hill dwellers, Kenyan farmers or Mexican peasants, Native Americans or West African sawyers—are the best custodians and conservators of existing forests and the best at giving new forests room to grow.

Let me say this clearly. I have been writing about the world’s environmental problems for forty years—about toxic dumps and the ozone layer, deforestation and our emptying oceans, urban smogs and species extinction, climate change and spreading deserts. Despite all this, I remain an optimist. For the world can turn. The forests can regrow. Join me on my journey through the world’s forests, past, present and—I profoundly believe—future.

Part I

Weather Makers

Before the existence of forests, the atmosphere on Earth was baking hot, bone dry, short of oxygen and thick with carbon dioxide. Today, three trillion trees keep us cool and watered, by soaking up the carbon dioxide and by sweating moisture to sustain flying rivers that deliver rain across the world. Their breath alters atmospheric chemistry too, making clouds and even generating the winds. Trees, in short, created and sustain the life-supporting climate of our planet. Here is their story.

—1—

Trees are Cool

Stomata, Transpiration and a Planet Transformed

TREES ARE THE BIGGEST and longest-living organisms on the planet. They can grow up to three hundred feet tall, weigh more than a thousand tons, and, in the case of North American bristlecone pines, sometimes live for more than four thousand years. In fact, their ability to clone replicas of themselves means they can effectively live forever. One cluster of forty thousand cloned aspens—or should that be aspen—in the Fishlake National Forest in Utah is a single male organism covering around a hundred acres and weighing more than six thousand tons. It is at least eighty thousand years old, making it probably the oldest mass of connected tree tissue on the planet, says British naturalist Richard Mabey. It hasn’t grown in a while, so it may be dying.1 Nobody can be sure of that either.

Still, trees are everywhere, and have been for hundreds of millions o f y ears. C loud forests c ling to mountaintops, m an-groves dangle their roots in tropical coastal waters, steaming jungles straddle the tropics, snow-covered boreal forests gird the Arctic, sporadic woodlands stretch across arid grasslands and half-submerged willows filter swamps in valley bottoms. Nothing is more typical of the land surface of our planet. Most of its biomass is trees. More than half those trees, and two-thirds of their carbon content, are in the tropics. But the largest single forest is stretched across eleven time zones of the Russian far north, which contains a quarter of all the world’s trees.

Trees don’t just dominate our living world; they made it. Before trees, some 300 million years ago, the continents were mostly hot, arid and lifeless. The atmosphere was very different. Carbon dioxide levels were ten times higher, and temperatures ten degrees warmer, says Claire Belcher of the University of Exeter. Oxygen levels were at half today’s level. There was little soil. Fierce winds whistled across bare rock. But trees created a world in which they, and we, could prosper. They transformed a barren planet and turned the world green, says David Beerling of the University of Sheffield.2

In the early days, they began by colonizing the only wet places, on coasts. They transpired moisture into the air, thus recycling rainfall from sea breezes to generate more rain in formerly arid regions inland. That allowed new trees to extend their domain, transforming the atmosphere as they went. As they grew in numbers, they also began to draw