By Agence France-Presse
Scientists in the United States have detected the highest levels of carbon dioxide that has warmed the planet in the Earth's atmosphere since the beginning of the record, sounding a new alarm about the relentless rise of man-made greenhouse gas emissions.
The Mauna Loa Observatory in Hawaii, which has monitored atmospheric CO2 levels since the late 1950s, detected 415.26 parts per million (ppm) on Saturday morning.
It was also the first time the observatory measured a daily baseline above 415 ppm.
The last time the Earth's atmosphere contained this CO2 was over three million years ago, when global sea level was several meters higher and parts of Antarctica were covered by forests.
"This shows that we are not on track to protect the climate. The number continues to increase and is increasing year after year, "Wolfgang Lucht of the Potsdam Institute for Climate Impact Research (PIK) told AFP.
"That number needs to stabilize."
But far from stabilizing, levels of CO2 – one of a trinity of greenhouse gases produced when fossil fuels are burned – are rising faster and faster.
Ralph Keeling, director of Scripps Institution's Oceanography CO2 Program, said the trend is likely to continue through 2019 – probably a year of El Nino when temperatures rise due to warmer ocean currents.
"The average growth rate remains high. The increase from last year will likely be around three parts per million, while the recent average was 2.5 ppm, "he said.
"We are probably seeing the effect of the mild El Niño conditions beyond the continued use of fossil fuels."
"Increasing the Rising Rate"
The 2015 Paris Accord calls on humanity to block the Earth's temperature rise by "well below" 2 degrees Celsius (3.6 Fahrenheit) compared to pre-industrial levels, and 1.5 C if possible.
The last four years have been the hottest four ever recorded, and despite the agreement in Paris and the growing public awareness of the problem, humanity continues to break its own emissions records year after year.
The average surface temperature of the Earth has already increased by 1.0C since pre-industrial times due to man-made emissions.
"The whole history of humanity is in a colder climate than now," Lucht said.
"Every time an engine runs, we emit CO2 and it needs to go somewhere. It does not miraculously disappear, it remains in the atmosphere.
"Despite the Paris climate agreement, despite all the speeches and protests – we are not seeing that we are doubling the curve yet," he added.
While there is some disagreement as to what constitutes "safe" atmospheric CO2 levels, there is a broad consensus that 350 ppm – a level surpassed in the late 1980s – would prevent uncontrolled global warming.
"350 ppm is a precautionary value because some of the consequences of being above 400 may still be evolving," Lucht said.
"But as we are not on the right track, any value we can stabilize is a victory."
The 415 ppm threshold was first exceeded earlier this month and has risen further.
"I'm old enough to remember when going 400 ppm was a big deal," said Gernot Wagner, an associate researcher at Harvard University on Twitter.
"Two years ago, we reached 410 ppm for the first time. So far, it's 415 ppm. And ah, the increase is increasing at an increasing rate!