Some environmental solutions are win-win, helping to slow down global warming and protect biodiversity. But others tackle one crisis at the expense of another. Growing trees in grasslands, for example, can destroy plant and animal life in a rich ecosystem, even if the new trees end up absorbing carbon.
What to do?
Unless the world stops treating climate change and the collapse of biodiversity as separate problems, none of the problems can be solved effectively, according to a report released Thursday by researchers from two major international science groups.
“These two topics are more closely related than originally thought,” said Hans-Otto Pörtner, co-chair of the scientific steering committee that produced the report. They are also inextricably linked to human well-being. But global policies typically target one or the other, with unintended consequences.
“If you only look at one angle, you’re missing out on a lot,” said Yunne-Jai Shin, marine biologist at the National Research Institute for Sustainable Development and co-author of the report. “Every action counts. “
How we got here
For years, a group of scientists and policymakers have studied and attempted to tackle the climate crisis, warning the world of the dangers of greenhouse gases that have built up in the atmosphere since the Industrial Revolution. The main culprit: the burning of fossil fuels.
Another group has studied and attempted to tackle the biodiversity crisis, alarming extinctions and collapse of ecosystems. The main culprits: habitat loss due to agriculture and, at sea, overfishing.
Both groups operated largely in their own silos. But their subjects are linked by something basic, literally: carbon itself.
The same element that makes up soot and heat-trapping carbon dioxide and methane is also a fundamental part of the natural world. It helps to form the very tissue of plants and animals on earth. It is stored in forests, wetlands, grasslands and on the ocean floor. In fact, terrestrial and aquatic ecosystems already retain half of human-made emissions.
Another link between climate and biodiversity: people have created emergencies on both fronts by using the planet’s resources in unsustainable ways.
Over the past two decades, the climate crisis has largely overshadowed the biodiversity crisis, perhaps because its threat seemed more serious. But the balance may be shifting. Scientists warn that the decline in biodiversity can lead to the collapse of ecosystems, threatening humanity’s food and water supply.
“Four or five degree climate change is such an existential threat to people, it’s hard to imagine,” said Paul Leadley, one of the authors and environmentalist at the University of Paris-Saclay.
And, he continued, “if we lose a very large fraction of species on earth, it is an existential threat.”
What is not working
Companies and countries are increasingly turning to nature to offset their emissions, for example by planting trees to absorb carbon. But the science is clear: Nature cannot store enough carbon to allow us to continue to spew greenhouse gases at our current rate.
“A clear first priority is emission reductions, emission reductions and emission reductions, “ says Dr Pörtner.
Just last month, the world’s leading energy agency said that if the world is to avoid the worst impacts of global warming, countries should stop approving new coal, oil and gas projects immediately.
To make matters worse, some measures used or proposed to combat climate change could devastate biodiversity.
“Some people are selling this message that if we cover the entire planet with trees, it will solve the climate problem,” Dr Leadley said. “This is a wrong message on many levels.“
In Brazil, parts of Cerrado, a biodiversity-rich savannah that stores large amounts of carbon, have been planted with monocultures of eucalyptus and pine trees in an attempt to meet a global reforestation target. The result, the researchers wrote separately, is “impending ecological disaster” as they destroy the native ecosystem and the livelihoods of local communities, including indigenous peoples.
Europe once hoped to be the world leader in biofuels until they realized they had led to deforestation and rising food prices. Another type of bioenergy, wood pellets, is currently booming in the Southeastern United States, despite concerns about pollution and loss of biodiversity.
Climate interventions tend to harm biodiversity more than the other way around, and some tradeoffs must occur, the authors wrote. Solar farms, for example, devour wildlife habitat, of particular concern for places where endangered species live. But above all, they generate clean energy.
The report highlights ways to mitigate damage to biodiversity, for example by grazing livestock around them, improving carbon stocks in soils and avoiding intact habitats. Solar farm pollinator gardens can help feed insects and birds. While wind farms can harm migrating birds, the authors note that modern wind turbines cause much less damage.
By protecting and restoring nature, according to the report, we can save biodiversity, help limit global warming, improve human well-being and even find protection against the consequences of climate change, such as increased flooding and flooding. storms.
In Senegal’s Casamance region, for example, local communities have restored mangroves and adopted sustainable fishing measures, improving their catches, bringing back dolphins and 20 species of fish, storing carbon and protecting their coastline, Pamela said. McElwee, environmental anthropologist at Rutgers University. who was one of the perpetrators.
“Mangroves are a really special type of ecosystem,” she said, “in that they do everything for humans”.
While mangroves are themselves vulnerable to climate change, Dr McElwee said they appear less endangered than previously thought, as restoration efforts are working.
In the Hindu Kush mountains of South Asia, a project has conserved an area the size of Belgium, restoring high-altitude forests and rangelands and protecting endangered snow leopards and musk deer, according to the report. , while keeping carbon out of the atmosphere. The 1.3 million people who live there, straddling Nepal, India and China’s Tibet Autonomous Region, have seen household incomes rise through tourism and sustainable agriculture.
Urban areas can also do their part with native trees, green spaces and coastal ecosystems, the researchers said.
The report was the first collaboration between the Intergovernmental Panel on Climate Change and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.
John P. Holdren, an environmental scholar at Harvard University and former White House science adviser who was not involved in the report, called it “a must read for our time.”
Brad plumer contributed reports.