The twin crises of climate change and biodiversity loss are intertwined: storms and forest fires are exacerbated, with as many as one million species at risk of extinction.
The solutions are not small or easy, but they do exist, scientists say.
A global roadmap published Wednesday in Nature identifies a pathway for absorbing nearly half of the carbon dioxide that has accumulated since the Industrial Revolution and preventing more than 70 percent of the predicted extinction of animals and plants on land. The key? The return of strategically 30 percent of the world̵
Researchers have found that this can be done while maintaining an abundance of food for humans while remaining within the time scale to keep global temperatures rising above 2 degrees Celsius, the top goal of the Paris Agreement.
“This is one of the most effective ways to combat climate change,” said Bernardo BN Strasbourg, one of the study’s authors and an environmental scientist at the Pontifical Catholic University in Rio de Janeiro and the International Institute for Sustainable Development. “And that’s one of the most important ways to avoid global extinction.”
The researchers used a map of the European Space Agency, which breaks down the planet’s surface into a network of plots classified by ecosystem: forests, wetlands, shrubs, pastures and drylands. Using an algorithm they developed, the scientists estimated which slopes, if returned to their natural state, would yield the highest returns to mitigate climate change and biodiversity loss at the lowest cost.
It was not enough to simply put one result on top of another. “If you really want to optimize for all three at once,” said Dr. Strasbourg, “this leads to a different map.”
A similar and complementary tool, The Global Safety Net, was launched last month. It identifies the most strategic 50 percent of the planet for protection, filtration for rare species, high biodiversity, large mammal landscapes, pristine desert and climate stabilization.
An increasing number of campaigns are seeking to address the global environmental emergency by protecting or restoring vast areas of the planet. The challenge in Bonn aims to restore 350 million hectares by 2030. The nature campaign is urging leaders to protect 30 percent of the planet by 2030.
In the latest study, scientists found that the benefits increase and decrease depending on how much land is restored.
Assigning 15 percent of strategic agricultural land, for example, could save 60 percent of extinctions and isolate about 30 percent of the accumulated carbon in the atmosphere. The authors estimate that globally, 55 percent of agricultural land can be returned to nature, while maintaining current levels of food production, using existing agricultural land more efficiently and sustainably.
“It’s really impressive,” says J. Leighton Reed, an environmental restoration specialist from Virginia Tech, who was not involved in the study. “The authors are doing a good job of acknowledging some of the limitations of the work while offering this great vision.”
The biggest challenges seem to be the political will and finding money to pay farmers to restore so much land in nature. But the authors cite hundreds of billions or trillions of dollars a year that subsidize fossil fuels and unsustainable agricultural practices.
“There’s a lot of money to invest,” said Robin Chazdon, a longtime biologist at the University of Connecticut and one of the study’s authors. “The world is invested in destruction.”
The study was requested by the United Nations Convention on Biological Diversity, a global treaty aimed at preserving biodiversity. One of the authors, David Cooper, is deputy executive secretary.
A recent report on the convention showed that world leaders have failed to meet their latest round of goals. The United States is the only country in the world, with the exception of the Vatican, that has not signed the treaty.
The study will be used to help inform global commitments under the UN conventions on biodiversity and climate next year. But as the new study highlights nature’s disregard for national borders, it is a diplomatic challenge.
“This outlines much higher benefits in general if you ignore the country’s borders and just look at where those priorities are,” Dr. Chazdon said. The most strategic places are distributed very unevenly; tropical forests and wetlands, for example, have enormous potential for carbon storage and biodiversity conservation.
“Are we saying, ‘We’re just going to give up all these benefits and be provincial about it?’ “Or are there ways for international cooperation?”
The authors note that the conservation of existing wildlife remains the most important way to protect biodiversity and see their proposed restoration as a critical complement. Other key steps listed by Dr. Strasbourg: Stopping the use of fossil fuels; reduction of food, energy and plastic waste; and making sustainable choices when buying things like food, cars and clothes.
“Once consumers start changing their models,” he said, “companies react very quickly.”