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In Mad Max: Fury Road, the Furiosa of Charlize Theron strives to return to "The Green Place", an oasis filled with trees in the lifeless wasteland that the Earth has become. When Furiosa arrives at the sacred place, however, she finds only skeletal trunks and sprawling dunes. She screams with anguish. Without trees, all hope seems lost.
Furiosa's feelings were justified. "Forests are the lifeblood of our world," said Meg Lowman, director of the Tree Foundation, a Florida-based nonprofit organization dedicated to research, exploration and development. Trees education. "Without them, we lose extraordinary and essential functions for life on Earth."
The services of trees on this planet range from carbon storage and soil conservation to the regulation of the water cycle. They support natural and human food systems and host countless species – including us, thanks to building materials. Yet we often treat trees as disposable: as objects to be harvested for economic purposes or as a disadvantage for human development. Since our species started practicing agriculture about 12,000 years ago, we have eliminated nearly half of the estimated 5,800 billion trees in the world, according to a 2015 study published in the Nature magazine.
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Much of the deforestation has occurred in recent years. Since the beginning of the industrial era, forests have decreased by 32%. Especially in the tropics, many trillions of trees in the world are falling rapidly, with about 15 billion trees cut each year, says the Naturestudy study. In many places, the loss of trees accelerates. In August, the National Institute of Space Research recorded an 84% increase in fires in the Brazilian Amazon rainforest compared to the same period in 2018. Burns are also on the rise in Indonesia and Madagascar.
Unless there is an unimaginable catastrophe, there is no scenario in which we will cut down all the trees on the planet. But to imagine a dystopian world of Mad Max style in which all the trees of the Earth died suddenly can help us understand how much we would be lost without them.
There would be massive extinctions of all groups of organisms, both locally and globally – Jayme Prevedello
"Let me start by saying how unsustainable a world without trees would be: they are irreplaceable," says Isabel Rosa, lecturer in environmental data analysis and analysis at Bangor University in Wales. . "If we get rid of all the trees, we will live [on] a planet that may no longer be able to support us. "
For starters, if trees disappeared overnight, so would biodiversity. Habitat loss is already the main factor of extinction in the world. The destruction of all the remaining forests would therefore be "catastrophic" for plants, animals, mushrooms and more, said Jayme Prevedello, an ecologist at the State University of Rio de Janeiro in Brazil. "There would be massive extinctions of all groups of organisms, both locally and globally."
The wave of extinctions would extend beyond forests, thus reducing wildlife that depended on isolated trees and small tree stands. In 2018, Prevedello and his colleagues found, for example, that overall species richness was 50 to 100% higher in areas with scattered trees than in open areas. "Even a single isolated tree in an open area can serve as a magnet for biodiversity, attracting and providing resources for many animals and plants," says Prevedello. "Therefore, even the loss of individual trees can have a significant impact on biodiversity at the local level."
The climate of the planet would also be radically changed in the short and long term. Trees intervene in the water cycle by acting as biological pumps: they suck water from the soil and deposit it in the atmosphere by converting it from liquid to vapor. In doing so, forests contribute to cloud formation and precipitation. Trees also prevent floods by holding back water rather than letting it rush into lakes and rivers, and protecting coastal communities from storm surges. They maintain the soils in place that would otherwise be driven by the rain and their root structures help the microbial communities to thrive.
Without trees, previously forested areas would become drier and more prone to extreme drought. When the rain falls, the floods will be disastrous. Massive erosion would have an impact on the oceans, the smothering of coral reefs and other marine habitats. The islands without trees would lose their barriers to the sea and many would be washed away. "Deleting trees means losing huge amounts of land at the expense of the ocean," says Thomas Crowther, global systems ecologist at ETH Zurich in Switzerland and lead author of the edition 2015 of Naturestudy.
In addition to intervening in the water cycle, trees have a localized cooling effect. They provide shade that maintains soil temperature and, as the darkest thing in the landscape, absorb heat rather than reflect it. In the process of evapotranspiration, they also channel the energy of solar radiation by converting liquid water into vapor. With all these cooling services lost, most of the tree sites were warming up immediately. In another study, Prevedello and his colleagues found that the total elimination of a 25 square kilometer forest plot resulted in an increase of local annual temperatures of at least 2 ° C in the tropics and regions. 1 ° C in temperate zones. The researchers also found similar temperature differences when comparing wooded and open areas.
On a global scale, trees are fighting against global warming by storing carbon in their trunks and removing carbon dioxide from the atmosphere. Deforestation already accounts for 13% of total global carbon emissions, according to an IPCC report released in August, while land-use change typically accounts for 23% of emissions. With the disappearance of all the trees on the planet, previously forested ecosystems "would only become a source of carbon dioxide emissions in the atmosphere, rather than a sink," says Paolo D'Odorico, professor of environmental science at the University of California. Berkeley.
Large amounts of carbon would enter the oceans, causing extreme acidification and killing almost anything except jellyfish.
Over time, Crowther predicts that we will witness the release of 450 gigatonnes of carbon into the atmosphere, more than double the amount already delivered by humans. For a time, this effect would be offset by smaller plants and grasses. But if small plants capture carbon faster than trees, they also release it faster. Eventually, perhaps over a few decades, these plants could no longer cope with imminent warming. "The timeline depends on where you are, because decomposition is much faster in the tropics than in the Arctic," says D'Odorico. "But once carbon dioxide is in the atmosphere, it does not matter if it comes from here or there."
As the decomposition slowly exploded this carbon bomb, the Earth would turn into a "hugely" hotter planet, says Crowther, as we had never seen before. Large amounts of carbon would also enter the oceans, causing extreme acidification and the death of almost anything, except for jellyfish, he says.
The sufferings of humanity would begin well before a catastrophic global warming. Increasing heat, disruption of the water cycle and loss of shade would kill victims among billions of people and livestock. Poverty and death would also affect many of the 1.6 billion people who depend directly on forests for their livelihoods, including food and medicine. More and more people would be unable to cook or heat their homes due to lack of firewood. Around the world, those whose work revolves around trees – loggers, paper makers, fruit growers or carpenters – would suddenly be out of work, ravaging the global economy. The timber sector alone employs 13.2 million people and generates $ 600 billion a year, according to the World Bank.
In the same way, the agricultural systems would be completely unbalanced. Shade crops such as coffee would decrease significantly, as would those dependent on arboreal pollinators. Due to fluctuations in temperature and precipitation, places that previously produced crops would have suddenly broken down while others, previously unsuitable, could become desirable. Over time, however, soils everywhere would deplete and require large amounts of fertilizer for crop survival. Extra heating would eventually make most places incultable and unbearable.
In addition to these devastating changes, there would be health impacts. Trees clean the air by absorbing pollutants and trapping particles on leaves, branches and trunks. Researchers at the US Forest Service have calculated that in the United States alone, trees eliminate 17.4 million tonnes of air pollution each year, representing a service valued at $ 6.8 billion (5%). £ 6 billion). At least 850 lives were saved and at least 670,000 cases of acute respiratory problems were avoided.
D'Odorico adds that we could also see epidemics of rare or new diseases transferred from species with which we do not normally come into contact. He and his colleagues found that the transfer of the Ebola virus into humans occurred in areas of forest fragmentation. Sudden loss of forests around the world could temporarily increase our exposure to zoonotic infections such as Ebola, Nipah and West Nile virus, as well as mosquito-borne diseases such as malaria and dengue.
A growing body of research is also showing that trees and nature are good for our mental well-being. The New York State Department of Environmental Protection, for example, recommends walking in forests to improve overall health, including reducing stress, increasing energy levels, and improving sleep. Trees also seem to help the body recover. A famous study from 1984 revealed that patients recovering from an operation were hospitalized shorter if they had a green view rather than a brick wall. More recent research has shown that spending time around herbs and trees reduces symptoms in children with Attention Deficit Hyperactivity Disorder (ADHD). Many studies have also found a positive correlation between green spaces and the performance of children in school. Trees can even help fight crime: a study found that a 10% increase in tree cover was associated with a 12% reduction in crime in Baltimore.
"Swimming in the forest" is now a medical prescription in Japan – Kathy Willis
"So many things that lead to physical and mental well-being problems can be dramatically reduced by spending time in a forest environment," says Kathy Willis, a professor of biodiversity at Oxford University. "That's why the" forest bath "is now a medical prescription in Japan."
The loss of trees would also be mourned at a deep cultural level. Trees are staples of countless childhoods and occupy a prominent place in art, literature, poetry, music, and so on. Since prehistory, they have integrated animist religions and play a leading role in other major religions practiced today. Buddha attained enlightenment after sitting under the Bodhi tree for 49 days, while Hindus worship Peepal trees, symbols of Vishnu. In the Torah and the Old Testament, God creates trees on the third day of creation – even before animals or humans – and in the Bible, Jesus dies on a wooden cross built from trees .
"Many people see forests with dollar signs," says Lowman. "But we have never found a monetary figure for the spiritual importance of forests."
Even if we could live in a world without trees, who would want it? – Thomas Crowther
All in all, humans would struggle to survive in a world without trees. Urbanized Western lifestyles would quickly become a thing of the past and many of us would die of starvation, heat, drought and floods. The surviving communities, Lowman thinks, would probably be the ones that have retained traditional knowledge about how to live in tree-less environments, such as Australian Aborigines. Crowther, on the contrary, suspects that life would only persist in a Mars-like colony made possible by technology and totally separate from the existence we have always known.
"Even if we could live in a tree-less world, who would want it?" Said Crowther. "This planet is unique compared to everything we know in the universe today because of this inexplicable thing called life, and without trees, almost all of it would simply be screwed."
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