Protected Areas Safeguard Climate

Protected Areas Safeguard Climate

The state of Rondônia in western Brazil—once home to 208,000 square kilometers (about 51.4 million acres) of forest—has become one of the most deforested parts of the Amazon. But in the western part of the state, a large oasis of tall trees and lush rainforest remains. This area is protected by the Uru-Eu-Wau-Wau Indigenous community and is one of thousands of protected areas around the world.

Scientists recently found that protected areas, including the Uru-Eu-Wau-Wau territory, store a substantial amount of carbon that would likely have been lost without protection. Using NASA data characterizing the three-dimensional structure of vegetation, the researchers found that if left unprotected, these ecosystems would likely have been degraded and deforested, emitting 9.65 billion tons of carbon over the past two decades. This is more carbon than is emitted every year in the United States.

“This is the first time we have been able to quantify the climate impact of protected areas,” said Laura Duncanson, a remote sensing scientist who led the research and is a principal investigator on the Global Ecosystem Dynamics Investigation (GEDI) science team. While many protected areas were established to safeguard biodiversity, this research demonstrates that they are also an effective tool in climate mitigation.

Data from NASA’s GEDI instrument on the International Space Station are used to produce 3D profiles of Earth’s surface. Duncanson and the research team used these data to map the structure and density of vegetation across the globe, and the carbon contained in its biomass. They found that biomass in protected areas was denser than in non-protected areas, especially in Brazil, Indonesia, and the United States.

“Getting an accurate estimate of the carbon stored in dense forests would not have been possible without GEDI data,” Duncanson said. GEDI’s detailed 3D observations allowed Duncanson and team to quantify the carbon stored in tall trees and the dense vegetation structure within protected ecosystems, and then compare that to the carbon stored in ecologically similar unprotected areas.

The map above shows GEDI biomass density data in the state of Rondônia in western Brazil—in megagrams of biomass per hectare—overlaid with the boundaries (in yellow) of protected areas, including the 18,000-square-kilometer (4.5-million-acre) Uru-Eu-Wau-Wau indigenous territory. Biomass (aboveground carbon) is much denser (dark green) within the protected area than outside of it.

The map below shows biomass density across GEDI’s observation area. The GEDI lidar mission collected six million laser observations every day between 2019 and 2023. There are gaps in GEDI’s coverage—and the instrument does not collect data north of about 52° latitude—which is evident as white space in both maps.

A key finding was that protected areas in the Brazilian Amazon accounted for one-third of the global carbon benefits of ecosystem protection. This is because unprotected forests in Brazil were being degraded or deforested for agriculture or other human developments.

“Massive deforestation events are happening in Brazil, which is why protection is especially important there,” Duncanson said. The forested Uru-Eu-Wau-Wau protected area, for example, is surrounded by farms. Despite the Indigenous territory being protected by law, the community has had to defend it from illegal burning, clearing, and encroachment.

The GEDI mission was paused in 2023 but is estimated to resume making observations from the International Space Station no earlier than 2024. Duncanson said a lot can be learned from multiple years of forest density observations. “There is a great deal of attention on forests as a critical tool for climate action,” said Duncanson. “A time series of GEDI observations could help inform what kinds of management practices and governance can help protect forest carbon over the long-term.”

NASA Earth Observatory images by Lauren Dauphin, using NASA GEDI data from Dubayah, R.O. et al. (2022). Story by Emily Cassidy.

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