Another day, another setback for our environmental prospects. The atmospheric concentrations of CO2 have entered “surreal territory” by reaching 415 parts per million for the first time in human history.
Carbon dioxide levels have been rising steadily this year, with the average for May peaking at 414.8 ppm, according to the Scripps Institution of Oceanography at the University of California San Diego in the United States.
“This is the highest seasonal peak recorded in 61 years of observations on top of Hawaii’s largest volcano, and the seventh consecutive year of steep global increases in concentrations of carbon dioxide, or CO2,” the institution explains.
“The 2019 peak value was 3.5 parts per million higher than the 411.3 ppm peak reached in May 2018; it represents the second-highest annual jump on record. Monthly CO2 values at Mauna Loa first breached the 400 ppm threshold in 2014,” It adds.
It’s in May each year that the highest monthly mean CO2 value is recorded because that’s when plants begin to suck large amounts of CO2 out of the atmosphere during their growing season in the northern hemisphere. In the fall, winter, and early spring, meanwhile, plants and soils release CO2, which causes levels of the gas to rise through May before they CO2 levels begin to fall in the summer.
It was the late American scientist Charles Keeling, who first observed this seasonal rise and fall in CO2 levels throughout the year. Tying it to the annual increases of atmospheric CO2 from manmade cause, he came up with a cycle that has come to be known as the Keeling Curve.
Over the past years CO2 levels in the atmosphere have been climbing measurably until they reached an all-time high of 415.26 ppm on June 1, thereby breaching another climatic threshold.
“The more you back off and look at the big picture the more you see the hand of human beings affecting the atmosphere,” says geochemist Ralph Keeling, Charles’s son who runs the Scripps program at Mauna Loa. “We’re in kind of surreal territory right now,” he adds.
“The rate of CO2 increase is still very high,” the scientist elucidates. “We’re likely seeing the effect of mild El Niño conditions on top of record fossil fuel use.”
Unless we start to rein in our runway emissions and fast, prospects for human civilization and for life on Earth will remain bleak, climate scientists warn. “Many proposals have been made to mitigate global warming, but without a rapid decrease of CO2 emissions from fossil fuels they are pretty much futile,” stresses Pieter Tans, a senior scientist at NOAA’s Global Monitoring Division.
