Reforestation

The reconstruction of arable land in tropical regions would store large amounts of CO2

By Donna Lu

A reforestation project in Brazil

Christian Ender / Getty Images

Restoring arable land to its natural state could be crucial to address carbon emissions and combat biodiversity loss. New models suggest that not only is the total land area restored, but also the location.

Bernardo Strassburg of the Pontifical Catholic University in Brazil and his colleagues have concluded that returning 30 percent of the arable land in several key areas of the world to its natural state would remove 465 gigatons of carbon dioxide from the atmosphere – almost half of the total increase in this greenhouse gas since the industrial revolution. The team doesn't go into exactly how long it would take for the restored land to capture that much CO2.

The restoration work would be so successful because natural forests and meadows can store far more carbon than arable land. Restoration would have other benefits as well: It could prevent 71 percent of the animal deaths expected in the coming decades.

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The high priority areas identified by the team include the coastal areas of Brazil and West Africa, and much of Southeast Asia.

The researchers analyzed data on 2,870 million hectares worldwide that have been converted to arable land. About 54 percent of the land was originally forest and 25 percent grassland. The rest was originally bushland, dry land, or wetland.

They rated the land types based on three criteria: animal habitat, carbon storage potential, and the cost-effectiveness of the transition to the original state. The top priority areas were the ones that were optimal for all three, but the team also considered a distribution that would restore a wide variety of ecosystems, including wetlands and bushland.

To study the impact on biodiversity, their model included maps of the geographic distribution of more than 22,000 animal species.

“There is a well-known ecological link between the loss of a species from its original range and the likelihood of extinction,” says Strasbourg. "When habitat is restored, the likelihood of extinction is reduced."

Even a smaller amount of restoration would still have a significant impact, according to the modeling. A 15 percent restoration could avoid around 60 percent of extinction and ultimately capture 299 gigatons of CO2.

The approach would require international cooperation, with restoration not tied to national borders. The modeling found that for a national-level restoration, where each individual country restores 15 percent of its converted land, but without working with neighbors to restore land according to a regional complementary strategy, the benefits of biodiversity may be beneficial in declining 28 percent and the climate by 29 percent.

Modeling can influence restoration commitments in the International Union for Conservation of Nature after 2020 of the global framework for biodiversity.

Journal reference: Nature, DOI: 10.1038 / s41586-020-2784-9