A NASA satellite has found another thing to blame on El Niño: A recent record high increase of carbon dioxide in the air.
A study published Thursday in the journal Science found that the super-sized El Niño a couple of years ago led to the biggest one-year jump in heat-trapping gas concentrations in at least 2,000 years.
The NASA satellite showed that El Niño made it more difficult for plants to suck up man-made carbon emissions and sparked fires that released more carbon into the atmosphere.
El Niño is the natural warming of parts of the central Pacific that affects weather around the world.
And NASA researchers suspect that the 2015-2016 El Niño, one of the largest on record, was responsible, but exactly how has been the subject of continuing research.
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NASA researchers suspect that the 2015-2016 El Niño, one of the largest on record, affected the amount of CO2 that Earth’s tropical regions released into the atmosphere. The super-sized El Niño led to the biggest one-year jump in heat-trapping gas concentrations in at least 2,000 years
NASA’S OCO-2 SATELLITE
NASA’s OCO-2 satellite, which launched in 2014, collects global measurements of atmospheric carbon dioxide.
It collects data with the precision needed to understand how the greenhouse gas – the principal human-produced driver of climate change – moves through the Earth system at regional scales, and how it changes time.
From space, the satellite can make about 100,00 global measurements of atmospheric carbon dioxide each day.
By analyzing data from NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite, the researchers concluded that impacts of El Niño-related heat and drought occurring in tropical regions of South America, Africa and Indonesia were responsible for the record spike in global carbon dioxide.
‘These three tropical regions released 2.5 gigatons (a billion tons) more carbon into the atmosphere than they did in 2011,’ said Dr Junjie Liu of NASA’s Jet Propulsion Laboratory (JPL) 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.
lOCO-2 data allowed us to quantify how the net exchange of carbon between land and atmosphere in individual regions is affected during El years.’
In 2015 and 2016, the satellite recorded atmospheric carbon dioxide increases that were 50 per cent larger than the average increase seen in recent years preceding these observations – measurements that were also consistent with those made by the NOAA.
These record increases took place even though emissions from human activities in 2015-2016 are estimate to have remained roughly the same as they were prior to the El Niño.
Using the satellite data, Dr 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 increase by 3 gigatons in 2015, due to El Niño.
About 80 per cent of that amount (2.5 gigatons) 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 2015 findings to those from a reference year – 2011 – using carbon dioxide data from a Japanese satellite.
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 Niño 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 Dr Annmarie Eldering of JPL.
‘The team’s findings imply that if future climate brings more or longer droughts, as the last El Niño did, more carbon dioxide may remain in the atmosphere, leading to a tendency to further warm Earth.’
While the three tropical regions released roughly the same amount of carbon dioxide into the atmosphere, the team found that temperature and rainfall changes influenced by the El Niño were different in each region.
In eastern and southeastern tropical South America, including the Amazon rainforest, severe drought spurred by El Niño made 2015 the driest year in 30 years. Temperatures were higher than normal, and these conditions reduced photosynthesis, meaning trees and plants absorbed less carbon, so there was a net increase in carbon released into the atmosphere
In eastern and southeastern tropical South America, including the Amazon rainforest, severe drought spurred by El Niño made 2015 the driest year in 30 years.
Temperatures were also higher than normal, and these drier and hotter conditions reduced photosynthesis, meaning trees and plants absorbed less carbon from the atmosphere, so there was a net increase in the amount of carbon released into the atmosphere.
By contrast, rainfall in tropical Africa was at normal levels, based on precipitation analysis that combined satellite measurements and rain gauge data, but ecosystems experienced hotter-than-normal temperatures.
Dead trees and plants decomposed more, leading to more carbon being released into the atmosphere.
And tropical Asia had the second-driest year in the past 30 years – its increased carbon release, mostly from Indonesia, was mainly due to increased peat and forest fires, also measured using satellite instruments.
While the three tropical regions released roughly the same amount of carbon dioxide into the atmosphere, the team found that temperature and rainfall changes influenced by the El Niño were different in each region
‘We knew El Niños 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 Dr Eldering.
‘OCO-2’s geographic coverage and data density are allowing us to study each region separately.’
Dr Scott Denning, a professor of atmospheric science at Colorado State University in Fort Collins, and an OCO-2 satellite team member who was not part of this study, said that while scientists have known for decades that El Niño influences 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 Dr Denning.
In this September 16, 2014 photo, firemen spray water in an attempt to extinguish bush fires on a peat land in Siak Riau province, Indonesia. A new NASA satellite finds another thing to blame on El Niño: A recent record high increase of carbon dioxide in the air. The super-sized El Niño a couple years ago added 2.5 billion tons of carbon into the atmosphere
‘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.
For example, it changes from season to season as plants grow and die, with higher concentrations in the winter and lower amounts in the summer.
But annually average carbon dioxide concentrations have increased year over year since the early 1800’s – the start of the Industrial Revolution.
WHAT IS THE EL NIÑO CLIMATE PHENOMENON?
El Niño and La Nina are the warm and cool phases (respectively) of a recurring climate phenomenon across the tropical Pacific – the El Nino-Southern Oscillation, or ‘ENSO’ for short.
The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, winds and precipitation.
These changes disrupt air movement and affect global climate.
ENSO has three phases it can be:
Maps showing the most commonly experienced impacts related to El Niño (‘warm episode,’ top) and La Niña (‘cold episode,’ bottom) during the period December to February, when both phenomena tend to be at their strongest
Before that time, Earth’s atmosphere naturally contained about 595 gigatons of carbon in the form of carbon dioxide – but now that figure is 850 gigatons.
The annual increase of atmospheric carbon dioxide 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, and the amount of carbon released into the atmosphere as a result of human activities also changes each year.
Earth’s land and ocean on average remove about half the carbon dioxide released from human emissions, with the other half leading to increasing atmospheric concentrations.
But in some years, natural processes remove as little as 20 per cent of human emissions, while in other years they remove around 80 per cent.