The 2015-16 El Nino did impact the atmosphere of the globe, besides causing severe heat and drought in tropical regions of South America, Africa and Indonesia. Now, the scientists at NASA have found out that this phenomenon was also responsible for the largest annual increase in atmospheric carbon dioxide (CO2) concentration in, at least, the last 2,000 years.

Scientists reached the conclusion, published in the journal Science as part of a collection of five research papers, by analyzing the first 28 months of data from NASA's Orbiting Carbon Observatory-2 (OCO-2) satellite.

"These three tropical regions released 2.5 gigatonnes (a billion tonnes) more carbon into the atmosphere than they did in 2011. 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," said the lead author of the study Junjie Liu of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, reported IANS.

In 2015 and 2016, the OCO-2 recorded an increase in CO2, which was 50% more than the average rise that has been noticed in the recent years. While in the recent years the increase had been four gigatonnes of carbon per year, during the said period it went up to 6.3 gigatonnes, stated the report.

This record rise in CO2 level occurred even though the amount of CO2 emission from human activities remained more or less similar before and after the El Nino.

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"Understanding how the carbon cycle in these regions (tropical regions of South America, Africa and Indonesia) 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. 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," said OCO-2 Deputy Project Scientist Annmarie Eldering of JPL.