Climate

NASA Reports Recent Surge in CO2 Emissions From Natural Sources

Forest fires in Indonesia, a hotter Africa, and a warmer, drier Amazon contributed to three consecutive years of record-setting global temperatures.

The recent Pacific Ocean hot streak known as El Niño led to a surge in carbon dioxide emissions from natural sources across the tropics, contributing to record global temperatures before fading.

The US space agency’s Orbiting Carbon Observatory-2 started beaming back planet-warming CO2 readings from space in 2014, around the time the periodic Pacific warming trend last emerged. The 2014-2016 El Niño drove average global temperatures to three straight annual records — and that warmth boosted the amount of CO2 that the world’s tropical forests gave up by about 2.5 billion tons in 2015, scientists working with the satellite data reported Thursday.

“In predictions of future climate, we see many models predicting more heat and drought,” Annmarie Eldering, an atmospheric scientist at NASA’s Jet Propulsion Laboratory and the deputy project scientist for OCO-2, told Seeker. “This suggests that if that happens, the land won’t absorb as much carbon and we’ll have a little bit extra boost of carbon in the atmosphere as we get more heat and drought. That’s important to know.”

Carbon normally flows through Earth’s ecosystem in a cycle. Plants suck it out of the air, use it for photosynthesis and release it back into the environment as they die and decay. People breathe it out. The ocean absorbs it.

But since the 1800s, when people started burning carbon-rich fuels like coal and oil for energy, carbon dioxide has been building up in the atmosphere, trapping heat and warming the planet. The natural carbon cycle typically absorbs about half of that output. That’s driven carbon dioxide concentrations upward by about 45 percent since 1750, to more than 400 parts per million today.

In a series of papers published in the research journal Science, Eldering and her colleagues used OCO-2 data to illustrate how Indonesia’s massive forest fires, a hotter, drier Amazon, and a warmer Africa added about 3 parts per million to that count. The tonnage emitted was about a quarter of what humans add to the atmosphere every year, said Scott Denning, a University of Northern Colorado atmospheric scientist.

“Each region responded differently, but all of them added to the increase,” Denning told reporters at a NASA news conference.

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Southeast Asia saw its second-driest year on record in 2015, and massive forest fires — many of them set to clear land for agriculture — turned carbon stored in trees and peat beds into CO2. In South America, hot, dry weather stunted plant growth, while warmer weather and relatively normal rainfall boosted the contributions of decaying biomass, said Junjie Liu, a research scientist at JPL.

“In terms of how much of human emissions are the natural systems taking out and dampening the effects, this suggests that dampening is going to slow down,” Eldering said. “So we need to be mindful of that when we consider emissions in the future.”

OCO-2 uses a spectrometer to calculate carbon dioxide levels by how sunlight reflects off CO2 in the air and can detect the fluorescence emitted by plants during photosynthesis. That’s allowed scientists to shed light on the carbon cycle in parts of the world where measurements were difficult before, Eldering said.

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Before 2009, most carbon dioxide concentrations came from ground stations, and places like the remote oceans or much of Africa had few regular measurements. A Japanese satellite, GOSAT, started taking readings from space in 2009. And OCO-2, which replaced a craft lost in a launch failure the same year, “lets you find more smaller signals and signals that are impacting smaller regions of the world.”

Its planned follow-up, OCO-3, would be installed on the International Space Station, but faces political obstacles: The Trump administration wants to scrub the project as part of steep proposed cuts to NASA’s Earth science programs, but a Senate bill working its way through Congress would keep the money flowing.

However, NASA Earth Sciences Division chief Michael Freilich told reporters that the Trump administration’s budget fully funds another satellite, the Geostationary Carbon Cycle Observatory, which would go aloft in 2022.

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