A new study from NASA and the National Center for Atmospheric Research suggests that tropical forests are soaking up more carbon dioxide than previously thought.
The study, recently published in Proceedings of the National Academy of Sciences, traces multiple lines of evidence that show tropical intake of CO2 “approximately balanc[es] net deforestation.” Further, a process known as the “fertilization effect” is providing a “substantial negative global feedback to atmospheric CO2 and climate.”
According to Motherboard, this is the first study to provide a “robust global estimate” of tropical forests’ mitigating effects on increasing levels of carbon in the atmosphere. Researchers gathered available data on CO2’s effect on the terrestrial carbon cycle across 12 orders of magnitude, starting from impacts on individual leaves and building up to the net impacts of carbon on a global scale.
Last November, Richard Heede, a researcher from the Climate Accountability Institute, linked 63 percent of worldwide greenhouse gas emissions to just 90 “carbon major” entities. Yet, while carbon emissions from the industrial sector have been on the rise since 2013, the increase in global CO2 is attributable to several sources. Carbon is also emitted when tropical forests are cleared for agriculture or ranching. The Peruvian Amazon, for instance, stores more carbon than the U.S. emits in a year, and when such forests are cut down, they release all of that stored CO2.
The Arctic, which is warming twice as fast as the rest of the planet, is also releasing greenhouse gases in what is becoming a positive feedback cycle for climate change. As more permafrost melts and releases carbon and methane into the air, the climate warms and causes more permafrost to melt. Together, melting permafrost and forest degradation are substantial contributors to climate change.
The new study suggests that this surplus of carbon may stimulate the growth of more plants, leading to a negative feedback cycle for climate change known as the “fertilization effect.” This effect roughly balances out the increasing emissions of carbon as plants absorb about 1.4 billion metric tons of CO2 per year.
“This is good news, because uptake in northern forests may already be slowing, while tropical forests may continue to take up carbon for many years,” said lead study author David Schimel in a press release.
It would appear that, in addition to harboring somewhere between 10 million and 30 million of the planet’s plant and animal species (or one-half to three-quarters of all life), tropical forests also soak up nearly one-third of the planet’s CO2 emissions.
However, despite the potentially good news of this study, its authors warn that this state of affairs is far from permanent. Over time, droughts and increasing wildfires due to climate change will subtract from forests’ overall ability to absorb carbon, leading to an ever-accelerating positive feedback cycle for extreme climate effects.