A new international study has found that the world’s tropical forests are absorbing significantly less carbon dioxide than scientists had previously estimated, raising fresh concerns about the planet’s ability to naturally slow climate change. The findings suggest that current climate models may be overestimating the role tropical forests play as carbon sinks, meaning more carbon dioxide could remain in the atmosphere and contribute to global warming.
The research, published in the Proceedings of the National Academy of Sciences (PNAS) analyzed atmospheric measurements collected during NASA’s Atmospheric Tomography (ATom) mission between 2016 and 2018. Using a specially equipped NASA DC-8 research aircraft.scientists flew across the globe from the Arctic to Antarctica, gathering carbon dioxide measurements from near the Earth’s surface to more than 40,000 feet above sea level.
Airborne Mission Reveals Hidden Carbon Imbalance
Researchers found higher concentrations of carbon dioxide above tropical regions than climate models had predicted. According to the scientists this indicates that tropical forests are absorbing less carbon than previously believed. The study also found differences in higher latitude regions, where forests may be absorbing more carbon than expected, fossil fuel emission estimates may be too high or both factors may be contributing to the discrepancy.
Lead author Britton Stephens of the U.S. National Center for Atmospheric Research said the findings reduce uncertainty in global carbon cycle models by as much as 50 percent. He explained that improving estimates of how much carbon is absorbed by forests oceans and soils is essential for accurately tracking greenhouse gas emissions and understanding their impact on Earth climate system.
Better Monitoring Needed to Improve Climate Predictions
Scientists explained that about half of the carbon dioxide released by human activities remains in the atmosphere, while the other half is absorbed by natural carbon sinks such as forests, oceans and soils. Determining exactly how much carbon each of these systems absorbs has long been one of the biggest challenges in climate science. The new airborne observations provide a more detailed and reliable picture than ground stations or satellites alone, both of which have important limitations.
The researchers say the findings highlight the need for regular global airborne monitoring missions. More comprehensive atmospheric observations could improve climate models, help distinguish between changes in natural carbon uptake and human emissions, and provide policymakers with more accurate information for climate planning.
The study adds to growing evidence that the ability of tropical forests to offset human caused carbon emissions may be weaker than previously believed, reinforcing the need to protect forests while rapidly reducing greenhouse gas emissions worldwide.