Carbon dioxide levels in the atmosphere accelerated at a record pace last year, reaching a concentration not seen in more than 3 million years, according to an annual report released by the United Nations. The last time levels were this high was during the Pliocene era, a time when the average global temperature was about 7°F warmer than it is today.
“Globally averaged concentrations of CO2 reached 403.3 parts per million (ppm) in 2016, up from 400.00 ppm in 2015 because of a combination of human activities and a strong El Niño event,” according to The Greenhouse Gas Bulletin, the UN weather agency’s annual flagship report.
This acceleration occurred despite a slowdown – and perhaps even a plateauing – of emissions because El Niño intensified droughts and weakened the ability of vegetation to absorb carbon dioxide. As the planet warms, El Niños are expected to become more frequent.
Carbon dioxide levels are increasing at a rate 100 times faster than at the end of the last ice age, according to the study. Population growth, deforestation and industrial pollution are among the culprits it identified.
The increase of 3.3 ppm is considerably higher than both the 2.3 ppm rise of the previous 12 months and the average annual increase over the past decade of 2.08 ppm. It is also well above the previous big El Niño year of 1998, when the rise was 2.7 ppm.
The study’s authors were critical of promises made by nations under the 2015 Paris agreement, saying that shortfalls in reaching those commitments will likely lead the world to exceed a target of keeping warming to 2°C. President Trump withdrew the U.S. from the Paris agreement in June.
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