A new NASA study provides space-based evidence that Earth’s tropical regions were the cause of the largest annual increases in atmospheric carbon dioxide concentration seen in at least 2,000 years.
Scientists suspected the 2015-16 El Nino — one of the largest on record — was responsible, but exactly how has been a subject of ongoing research. Analyzing the first 28 months of data from NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite, researchers conclude impacts of El Nino-related heat and drought occurring in tropical regions of South America, Africa and Indonesia were responsible for the record spike in global carbon dioxide. The findings are published in the journal Science Friday as part of a collection of five research papers based on OCO-2 data.
“These three tropical regions released 2.5 gigatons more carbon into the atmosphere than they did in 2011,” said Junjie Liu of NASA’s Jet Propulsion Laboratory in Pasadena, California, who is lead author of the study. “Our analysis shows this extra carbon dioxide explains the difference in atmospheric carbon dioxide growth rates between 2011 and the peak years of 2015-16. OCO-2 data allowed us to quantify how the net exchange of carbon between land and atmosphere in individual regions is affected during El Nino years.” A gigaton is a billion tons.
In 2015 and 2016, OCO-2 recorded atmospheric carbon dioxide increases that were 50 percent larger than the average increase seen in recent years preceding these observations. These measurements are consistent with those made by the National Oceanic and Atmospheric Administration (NOAA). That increase was about 3 parts per million of carbon dioxide per year — or 6.3 gigatons of carbon. In recent years, the average annual increase has been closer to 2 parts per million of carbon dioxide per year — or 4 gigatons of carbon. These record increases occurred even though emissions from human activities in 2015-16 are estimated to have remained roughly the same as they were prior to the El Nino, which is a cyclical warming pattern of ocean circulation in the central and eastern tropical Pacific Ocean that can affect weather worldwide.
Using OCO-2 data, Liu’s team analyzed how Earth’s land areas contributed to the record atmospheric carbon dioxide concentration increases. They found the total amount of carbon released to the atmosphere from all land areas increased by 3 gigatons in 2015, due to the El Nino. About 80 percent of that amount — or 2.5 gigatons of carbon — came from natural processes occurring in tropical forests in South America, Africa and Indonesia, with each region contributing roughly the same amount.
The team compared the 2015 findings to those from a reference year — 2011 — using carbon dioxide data from the Japan Aerospace Exploration Agency’s Greenhouse Gases Observing Satellite (GOSAT). In 2011, weather in the three tropical regions was normal and the amount of carbon absorbed and released by them was in balance.
“Understanding how the carbon cycle in these regions responded to El Nino will enable scientists to improve carbon cycle models, which should lead to improved predictions of how our planet may respond to similar conditions in the future,” said OCO-2 Deputy Project Scientist Annmarie Eldering of JPL. “The team’s findings imply that if future climate brings more or longer droughts, as the last El Nino did, more carbon dioxide may remain in the atmosphere, leading to a tendency to further warm Earth.”
The last El Nino in 2015-16 impacted the amount of carbon dioxide that Earth’s tropical regions released into the atmosphere, leading to Earth’s recent record spike in atmospheric carbon dioxide. The effects of the El Nino were different in each region.Credit: NASA-JPL/Caltech
While the three tropical regions each released roughly the same amount of carbon dioxide into the atmosphere, the team found that temperature and rainfall changes influenced by the El Nino were different in each region, and the natural carbon cycle responded differently. Liu combined OCO-2 data with other satellite data to understand details of the natural processes causing each tropical region’s response.
In eastern and southeastern tropical South America, including the Amazon rainforest, severe drought spurred by El Nino made 2015 the driest year in the past 30 years. Temperatures also were higher than normal. These drier and hotter conditions stressed vegetation and reduced photosynthesis, meaning trees and plants absorbed less carbon from the atmosphere. The effect was to increase the net amount of carbon released into the atmosphere.
In contrast, rainfall in tropical Africa was at normal levels, based on precipitation analysis that combined satellite measurements and rain gauge data, but ecosystems endured hotter-than-normal temperatures. Dead trees and plants decomposed more, resulting in more carbon being released into the atmosphere. Meanwhile, tropical Asia had the second-driest year in the past 30 years. Its increased carbon release, primarily from Indonesia, was mainly due to increased peat and forest fires — also measured by satellite instruments.
“We knew El Ninos were one factor in these variations, but until now we didn’t understand, at the scale of these regions, what the most important processes were,” said Eldering. “OCO-2’s geographic coverage and data density are allowing us to study each region separately.”
Scott Denning, professor of atmospheric science at Colorado State University in Fort Collins and an OCO-2 science team member who was not part of this study, noted that while scientists have known for decades that El Nino influences the productivity of tropical forests and, therefore, the forests’ net contributions to atmospheric carbon dioxide, researchers have had very few direct observations of the effects.
“OCO-2 has given us two revolutionary new ways to understand the effects of drought and heat on tropical forests: directly measuring carbon dioxide over these regions thousands of times a day; and sensing the rate of photosynthesis by detecting fluorescence from chlorophyll in the trees themselves,” said Denning. “We can use these data to test our understanding of whether the response of tropical forests is likely to make climate change worse or not.”
The concentration of carbon dioxide in Earth’s atmosphere is constantly changing. It changes from season to season as plants grow and die, with higher concentrations in the winter and lower amounts in the summer. Annually averaged atmospheric carbon dioxide concentrations have generally increased year over year since the early 1800s — the start of the widespread Industrial Revolution. Before then, Earth’s atmosphere naturally contained about 595 gigatons of carbon in the form of carbon dioxide. Currently, that number is 850 gigatons.
The annual increase in atmospheric carbon dioxide levels and the magnitude of the seasonal cycle are determined by a delicate balance between Earth’s atmosphere, ocean and land. Each year, the ocean, plants and trees take up and release carbon dioxide. The amount of carbon released into the atmosphere as a result of human activities also changes each year. On average, Earth’s land and ocean remove about half the carbon dioxide released from human emissions, with the other half leading to increasing atmospheric concentrations. While natural processes are responsible for the exchange of carbon dioxide between the atmosphere, ocean and land, each year is different. In some years, natural processes remove as little as 20 percent of human emissions, while in other years they scrub as much as 80 percent.
OCO-2, launched in 2014, gathers global measurements of atmospheric carbon dioxide with the resolution, precision and coverage needed to understand how this important greenhouse gas — the principal human-produced driver of climate change — moves through the Earth system at regional scales, and how it changes over time. From its vantage point in space, OCO-2 is able to make roughly 100,000 measurements of atmospheric carbon dioxide each day, around the world.
Institutions involved in the Liu study include JPL; the National Center for Atmospheric Research in Boulder, Colorado; the University of Toronto; Colorado State University; Caltech in Pasadena, California; and Arizona State University in Tempe.
For more information on NASA’s Orbiting Carbon Observatory-2 mission, visit:
NASA Satellite Reveals Source of El Niño–Fueled Carbon Dioxide Spike
The OCO 2 mission serendipitously coincided with one of the strongest El Niños on record
For every ton of carbon dioxide emitted by a power plant’s smokestack or a car’s exhaust pipe, some portion will stay in the Earth’s atmosphere, raising global temperatures, while the rest is absorbed by the oceans or ecosystems on land.
But which parts of the ocean or biosphere act as net sources of carbon dioxide (CO2) and which take up more than they emit into the atmosphere, has been an open question. Figuring that out, as well as understanding what mechanisms govern that interplay and how they might change along with the climate, has been an open question and one that is key to understanding how global warming will progress.
The 2014 launch of the Orbiting Carbon Observatory-2 satellite was aimed at beginning to piece together some answers by monitoring the comings and goings of CO2 from the atmosphere with unprecedented precision and over large regions. [The Reality of Climate Change: 10 Myths Busted]
So far, the mission has done that and has turned up some surprises along the way. The mission serendipitously coincided with one of the strongest El Niños (an ocean and atmosphere cycle that impacts global weather) on record, allowing scientists to see how the carbon cycle responded and pinpoint exactly where the resulting record pulse of CO2 that entered the atmosphere came from. The satellite’s instruments also unexpectedly proved capable of distinguishing the relatively small CO2 signatures of cities and even volcano plumes.
“We’re very, very happy with these results,” deputy project scientist Annmarie Eldering, of NASA’s Jet Propulsion Laboratory, told Live Science.
But the findings, described in series of five papers in the Oct. 13 issue of the journal Science, are just the first steps at getting a better handle on the carbon cycle (how carbon flows through land and sea ecosystems and the atmosphere), as OCO-2 heads into an expected extended mission and other space-based projects are scheduled to follow in its wake.
LUCK AND SURPRISES
Carbon dioxide is added to and removed from the atmosphere by a range of competing processes. On land, for example, the photosynthesis of plants takes up CO2, while the decay of plant matter and wildfires release it back into the atmosphere. [Here’s How Carbon Dioxide Warms the Planet]
Scientists knew that El Niños were another factor that caused more CO2 to build up in the Earth’s atmosphere, and from the 1997-1998 major El Niño, they had some suspicions on why that was. For one thing, El Niño tends to lead to drying in parts of the tropics, resulting in less photosynthesis and less uptake of carbon dioxide.
What project scientists couldn’t know when the satellite rocketed into space on July 2, 2014, was that it would be perfectly poised to observe how one of the strongest El Niños in the books affected the carbon cycle.
“Sometimes you get really lucky,” said Galen McKinley, a carbon cycle scientist at Columbia University’s Lamont Doherty Earth Observatory.
These effects were in evidence during the 2015-2016 event, which caused the biggest year-over-year jump in global CO2 concentrations on record, according to the National Oceanic and Atmospheric Administration. But OCO-2 revealed, as is so often the case in science, that the picture was more complicated than previously thought. [CO2 Satellite: NASA’s Orbiting Carbon Observatory-2 Mission in Photos]
The satellite’s observations let project scientists piece together the sequence of events of the carbon cycle’s response as the El Niño geared up and then reached its peak. They saw that at first there was a tiny dip in carbon dioxide levels over the tropical Pacific because of changes in the structure of the underlying ocean that meant waters gave off less CO2. But that slight decrease was quickly overtaken by the much larger response from terrestrial biomass as drought, heat and wildfires took a toll and caused less CO2 to be absorbed and more to be released. [Top 10 Deadliest Natural Disasters in History]
The ocean signal “was really a big surprise to us,” said Abhishek Chatterjee, a scientist with University Space Research Association working at NASA’s Goddard Spaceflight Center. The response had been inferred before, “but it was never observed to the degree that we could” with OCO-2, he said.
The team was able to take the analysis a step further by using OCO-2’s capability to detect a signature of photosynthesis, which is a marker of the productivity of land plants. Together, the data showed that while the tropical areas of Southeast Asia, South America and Africa all added about the same amount of CO2 into the atmosphere, they did so for different reasons. In Southeast Asia, the hot, dry conditions brought on by El Niño made the region more vulnerable to fire, which releases CO2 into the atmosphere. In South America, dry conditions tamped down plant productivity, meaning the biosphere took up less carbon dioxide, so that the region became a net source of CO2. And in Africa, while rainfall was about normal, exceptional heat increased plant respiration, which caused more CO2 emissions.
MORE WORK TO DO
OCO-2 sensors were also surprisingly good at picking out much smaller CO2 signatures, such as the plume of Vanuatu’s Yasur volcano and the contrast between Los Angeles’ relatively higher CO2 levels compared with the surrounding suburban and rural areas. [Earth from Above: 101 Stunning Images from Orbit]
The satellite could also see how the difference between the urban core and rural areas declined in the summer because plants in the region took up some of the excess.
The ability of satellites to pinpoint these signatures has implications for a wide range of applications, including monitoring emissions to make sure cities and countries are complying with their pledges to reduce CO2. Satellite CO2 measurements could also provide earlier warnings of volcanic eruptions, said Florian Schwandner, also of NASA’s JPL, as CO2 emissions from volcanoes increase before an eruption.
OCO-2 has completed its initial two-year planned mission and is expected to begin a three-year extended mission once NASA officials sign off on it, said Eldering, the deputy project scientist.
Scientists are also hoping that two other planned missions go as scheduled to build on OCO-2’s work. One, called OCO-3, will use leftover spare parts from OCO-2 and would be mounted on the International Space Station to allow scientists to point at features of interest. That mission has been slated to be cut by the Trump administration, though it remains to be seen whether Congress will go along with that plan.
The other, called the Geostationary Carbon Cycle Observatory, would be able to measure CO2 over continuous areas, such as the U.S., something OCO-2 can’t do.
“It’s very exciting science, [but] there’s a lot more work to do,” McKinley said.
CO2 emission from humans hasn’t risen in 3 years, i.e. the increase is all natural, as documented above.
So, why isn’t the climate scam ending??
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.. because it’s not about CO2, weather, sea level rise or polar bears, not even about science. Simply because, communism was never about science, logic or evidence, if it was there wouldn’t be any communism – ever!