NASA explained the appearance of extra 2.5 gigatonnes of CO₂ in the atmosphere in 2015

Due to fluctuations in the temperature of the surface water layer in the equatorial part of the Pacific Ocean, each of the three tropical regions in 2015-2016 released a record amount of CO ₂ into the atmosphere.

From the beginning of the 19th century, the amount of CO ₂ in the Earth’s atmosphere has been continuously increasing every year. Before the Great Industrial Revolution, there were approximately 595 gigatons of carbon in the form of CO ₂ in the atmosphere , and now this amount is 850 gigatons.

The oceans and land each year process about half of the CO ₂ emissions that occur as a result of human life. In different years, the percentage of processing ranges from 20% to 80%. Untreated CO ₂accumulates in the atmosphere, increasing the carbon balance every year and enhancing the greenhouse effect.

But in 2015-2016 a strange event happened, which was previously recorded by the US National Oceanic and Atmospheric Administration. During these years, the CO ₂ in the atmosphere has sharply jumped to its highest level over the past 2,000 years, although emissions from human activities remained at the same level. NASA has now explained this phenomenon by analyzing readings from the new Orbiting Carbon Observatory-2 (OCO-2) satellite, NASA's first and only observatory to monitor CO ₂ .

The National Oceanic and Atmospheric Administration suggested that the emission of "extra" 2.5 gigatons of CO ₂and a record jump in carbon dioxide in the atmosphere, followed by the greenhouse effect and natural disasters around the globe - this is a manifestation of the El Nino effect , that is, cyclical fluctuations in the temperature of the surface layer of water in the equatorial part of the Pacific Ocean. It is known that El Nino has a significant impact on the Earth’s climate. Due to temperature fluctuations, the El Niño flow occurs when the region of heated surface water shifts eastward. At the same time, the trade winds are weakening or stopping altogether, and the ascent to the surface of deep waters in the eastern Pacific Ocean, off the coast of Peru, is slowing down.

It was suggested that increasing CO ₂ levelssomehow related to El Nino. But the specific chain of interconnections that led to such consequences was not clear. The OCO-2 satellite made it clear: now these climatic effects can be linked.


Observatory OCO-2. Render: NASA / JPL-Caltech

An analysis of the data after the first 28 months of the OCO-2 Observatory concluded that El Niño caused an abnormal temperature rise and drought in the tropical regions of South America, Africa and Indonesia. In 2015-2016, the El Nino course was the strongest since the 1950s, therefore, the effect manifested itself so sharply. In South America, there was a severe drought in the last 30 years, the temperature was also above normal. Extreme weather conditions suppressed vegetation and reduced photosynthesis, which caused trees and plants to extract less carbon dioxide from the atmosphere. Accordingly, the balance of absorbed and released CO ₂ shifted in the negative direction.

In Africa, El Nino manifested itself differently. There, the amount of precipitation remained at a normal level, but the temperature turned out to be much higher than average. In the hot atmosphere, dead trees and plants began to decompose faster, increasing carbon dioxide emissions into the atmosphere. Although the effect manifested itself differently, the result was the same: an extra 0.8 gigatons of carbon in the atmosphere.

As a result, in 2015, these tropical regions released into the atmosphere 2.5 ± 0.34 gigatons of CO ₂ more than in 2011 (in balance). Although usually the amount of carbon in the atmosphere in previous years increased by an average of 4 gigatons, in 2015 it immediately increased by 6.3 gigatons, although emissions from human activities remained at the same level.

In total, carbon emissions from terrestrial land in 2015 due to El Niño increased by 3 gigatons, of which more than 80% (2.5 gigatons) were provided by the above-mentioned tropical regions.

Comparison with 2011 was carried out according to the Japanese Greenhouse Gases Observing Satellite (GOSAT). Six years ago, the climate in those areas was normal, and the amount of carbon dioxide absorbed and released was balanced.

The OCO-2 satellite will continue to work: it is capable of taking up to 100,000 measurements per day of carbon dioxide concentration in different regions of the Earth.

The scientific article was published on October 13, 2017 in the journal Science (doi: 10.1126 / science.aam5690).