Home / Health / BBC – Future – What would happen if all the world's trees disappeared?

BBC – Future – What would happen if all the world's trees disappeared?

In Mad Max: Fury Road, Charlize Theron's Furiosa strives to return to "the green place" – a tree-filled oasis in the otherwise lifeless wasteland that the earth has become. When Furiosa arrives at the sacred site, however, she only finds skeletal trunks and scattered sand dunes. She screams in agony. Without trees, all hope seems lost.

Furiosa's feelings were motivated. "Forests are our lifespan," says Meg Lowman, director of the Tree Foundation, a nonprofit organization in Florida dedicated to tree research, exploration and education. "Without them, we will lose extraordinary and essential functions for life on earth."

The trees' services to this planet range from collagen storage and soil conservation to water cycle regulation. They support natural and human food systems and provide homes for countless species ̵

1; including us, through building materials. Yet we often treat trees as single-use: as something to be harvested for financial gain or as a nuisance in human development. Since our species began to practice agriculture about 12,000 years ago, we have cleared nearly half of the world's estimated 5.8 trillion trees, according to a 2015 study published in the journal Nature.

You might also like:

Much of the deforestation has happened in recent years. Since the beginning of the industrial period, forests have decreased by 32%. Especially in the tropics, many of the world's remaining three trillion trees fall quickly, with about 15 billion cuts each year, says Naturestudy. In many places, tree loss accelerates. In August, the National Institute for Space Research showed an 84% increase in fires in the Brazilian Amazon rainforest compared to the same period in 2018. Slash-and-burn is also particularly on the rise in Indonesia and Madagascar.

Without the obstacle of an unimaginable disaster, there is no scenario under which we would fall every tree on the planet. But imagining a dystopian, Mad Max-style world where all the trees on earth suddenly died can help us estimate how lost we would be without them.

There would be massive extinctions of all groups of organisms, both locally and globally – Jayme Prevedello

"Let me just start with how horrible a world without trees would be – they are replaceable," said Isabel Rosa, lecturer in environmental data and analysis at Bangor University in Wales. "If we get rid of all the trees, we will live [on] a planet that may not be able to sustain us anymore."

Initially, if trees disappeared overnight, so would much of the planet's biodiversity. Habitat loss is already the main driver of extinction worldwide, so the destruction of all remaining forests would be "catastrophic" for plants, animals, fungi and more, says Jayme Prevedello, ecologist at Rio de Janeiro State University in Brazil. "There would be massive extinctions of all groups of organisms, both locally and globally."

The wave of extinctions would extend beyond forests and lose wildlife due to single trees and small tree stands as well. In 2018, for example, Prevedello and his colleagues found that total 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 'magnetic biodiversity', attracting and providing resources for many animals and plants," Prevedello says. "Therefore, even losing individual trees can have a major impact on biodiversity locally."

The planet's climate would also change drastically in the short and long term. Trees mediate the water cycle by acting as biological pumps: they suck water from the soil and deposit it into the atmosphere by converting it from liquid to steam. By doing this, forests contribute to cloud formation and precipitation. Trees also prevent flooding by catching water rather than letting it rush into lakes and rivers, and by buffing coastal communities from storm surges. They hold soil in place that would otherwise wash away in the rain, and their root structures help microbial communities thrive.

Without trees, former forest areas would be drier and more prone to extreme drought. When rain came, the floods would be catastrophic. Massive erosion would affect the oceans, smother coral reefs and other marine habitats. Islands peeled from trees would lose their barriers to the sea, and many would be washed away. "Removing trees means losing huge amounts of land to the sea," says Thomas Crowther, a global systems ecologist at ETH Zurich in Switzerland and lead author of the Nature Study 2015.

In addition to mediating the water cycle, trees have a localized cooling effect. They provide shade that maintains soil temperatures and, as the darkest in the landscape, absorbs heat rather than reflects it. In the process of evapotranspiration, they also channel energy from solar radiation to the conversion of liquid water into steam. With all lost cooling services, most places where trees used to stand were immediately warmer. In another study, Prevedello and his colleagues found that complete removal of a 25-square-foot large forest caused local annual temperatures to increase by at least 2 ° C in tropical and 1 ° C in temperate areas. Researchers have also found similar temperature differences when comparing forest areas and open areas.

On a global scale, trees fight the warming caused by climate change by storing carbon in their trunks and removing carbon dioxide from the atmosphere. Deforestation already accounts for 13% of total global carbon dioxide emissions, according to an IPCC report published in August, while land use change generally accounts for 23% of emissions. With all the trees on the planet wiped out, previously wooded ecosystems "would just be a source of carbon dioxide emissions into the atmosphere, rather than a sinker," said Paolo D & # 39; Odorico, professor of environmental science at the University of California, Berkeley.

Large amounts of coal would run into the oceans, causing extreme acidification and death, perhaps anything but jellyfish. with. For a while, this effect is offset by smaller plants and grasses. But while smaller plants capture carbon faster than trees, they also release it faster. Eventually – perhaps for a few decades – these plants would no longer be able to ward off the upcoming warming. "The timeline depends on where you are, because the degradation is much faster in the tropics than the Arctic," said O'Dorico. "But once carbon dioxide is in the atmosphere, it doesn't matter if it comes from here or from there."

When the degradation slowly detonated this ticking carbon bomb, the earth would turn into a "very" warmer planet, Crowther says – which we have not experienced since before trees were developed. Large quantities of coal would also run into the oceans, causing extreme acidification and possibly kill anything but jellyfish, he says.

The suffering of humanity would begin long before catastrophic global warming took place. The increased heat, the disturbance of the water cycle and the loss of shade would take a deadly toll for billions of people and livestock. Poverty and death would also reduce many of the 1.6 billion people who currently rely directly on forests for their livelihoods, including harvesting food and medicine. More people would still not be able to cook or heat their homes due to the lack of firewood. Around the world, those whose work revolves around trees – whether as carpenters or paper makers, fruit growers or carpenters – would suddenly be unemployed and destroy the global economy. The timber industry alone provides employment to 13.2 million people and generates $ 600 billion (£ 500 billion) each year, according to the World Bank.

Agricultural systems would likewise swing wildly out of the closet. Shade crops like coffee would drastically reduce, as do those who rely on tree-dwelling pollinators. Due to fluctuations in temperature and precipitation, places that previously produced crops would suddenly fail, while others that were previously unsuitable may be desirable. But over time, soil would be dropped everywhere, requiring significant amounts of fertilizer for the crops to survive. Further heating would eventually make most places uncultivable and unresolved.

On top of these devastating changes, there would be health effects. Trees clean the air by absorbing pollutants and trapping particles on their leaves, branches and stems. Researchers from the US Forest Service have estimated that trees in the United States alone remove 17.4 million tonnes of air pollution each year, a service estimated at $ 6.8 billion (£ 5.6 billion). At least 850 lives are saved as a result and at least 670,000 cases of acute respiratory distress are avoided.

D & # 39; Odorico adds that we can also see outbreaks of rare or new diseases transmitted from species that we do not normally come into contact with. He and his colleagues found that Ebola's transmission to humans takes place in hotspots of forest fragmentation. A sudden loss of forests everywhere could trigger a temporary increase in our exposure to zoonotic infections such as Ebola, Nipah virus and West Nile virus, he says, as well as for mosquito-borne diseases such as malaria and dengue fever.

A growing body of research also points to the fact that trees and nature are good for our mental well-being. For example, the New York State Department of Environmental Conservation recommends going into forests to increase public 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 surgery experienced shorter hospital stays if they had a green view rather than one of a brick wall. Recent research revealed that spending time around grass and trees reduces the symptoms of children with hyperactivity disorders in attention deficit, and many studies have also documented a positive relationship between green spaces and children's performance in school. Trees can even help fight crime: one study found that a 10% increase in tree protection was associated with a 12% decrease in crime in Baltimore.

"Forest bathing" is now a medical prescription in Japan – Kathy Willis [19659008] "So many things that lead to physical and mental well-being can be significantly reduced by spending time in a forest area," said Kathy Willis, professor of biodiversity at the University of Oxford. "That's why" forest bathing "is now a medical prescription in Japan."

The loss of trees would also be mourned on a deep, cultural level. Trees are staples of countless childhoods and have strong elements in art, literature, poetry, music and more. They have taken part in animistic religions since prehistory and play prominent roles in other major religions practiced today. Buddha attained enlightenment after sitting under the Bodhi tree for 49 days, while Hindus worship at the Peepal tree, which serves as a symbol of Vishnu. In the Torah and Old Testament, God creates trees on the third day of creation – even before animals or humans – and in the Bible, Jesus dies on a tree cross made of trees.

"Many people look at forests with dollar signs," says Lowman. "But we have never provided a monetary figure for the spiritual significance of forests."

Even if we could live in a world without trees, who would? – Thomas Crowther

Everyone told us that people would struggle to survive in a world without trees. Urbanized, western lifestyles would quickly become a story and many of us would die of starvation, heat, drought and flooding. Surviving communities, Lowman believes, would probably be those who have retained traditional knowledge of how to live in treeless environments, such as Australia's Aboriginal people. Crowther, on the other hand, suspects that life would only last in a Mars-like colony, made possible by technology and completely separate from the existence we have always known.

"Although we could live in a world without trees, who would?" Says Crowther. "This planet is unique from everything else that we currently know in the universe because of this inexplicable thing called life, and without trees, almost everything would just be screwed. "

Join a million Future fans by liking us on Facebook or follow us on Twitter or Instagram .

If you liked this story, [19659032] sign up for the weekly bbc.com newsletter called "The Essential List". of stories from BBC Future, Culture, Worklife and Travel, delivered to your inbox every Friday.

Source link