WASHINGTON – Greenhouse gases in the Earth’s atmosphere reached another grim milestone earlier this year as carbon dioxide levels surpassed the symbolic threshold of 400 parts per million across much of the planet, the premier global meteorological association confirmed in a report to be released Monday.
Figures compiled by the World Meteorological Organization showed growth – and new records – in the concentrations of all three of the most important heat-trapping gases, continuing a long-term trend with ominous implications for climate change, the group said.
The report is likely to add to concerns about global warming in a year that climate experts say is almost certain to surpass 2014 as the hottest year in recorded history.
“We are moving into unchartered territory at a frightening speed,” WMO Secretary General Michel Jarraud said of the report’s findings.
The WMO maintains the world’s biggest network of sensors detecting changes in the makeup of the Earth’s atmosphere.
For decades it has tracked rising concentrations of greenhouse gases such as carbon dioxide, a naturally occurring chemical compound that is vital for plant life and also acts as an insulating blanket, trapping the sun’s heat and making the planet warmer than it would otherwise be.
With the burning of fossil fuels, levels of atmospheric carbon dioxide have risen steadily, soaring from about 278 ppm during pre-industrial times to above 390 ppm by the start of the current decade.
Many scientists contend that the carbon dioxide levels should remain well below 400 ppm to avoid long-term disruptions to the Earth’s climate.
But since 2012, several of the WMO’s 125 individual monitoring stations have detected readings above that threshold.
The global average climbed to 397.7 ppm in 2014, the WMO report said, and in early 2015, it exceeded 400 ppm for the first time, the organization’s data shows.
The level then dipped, as usual, with the arrival of spring growing season in the Northern Hemisphere, when trees and other plants take carbon dioxide out of the atmosphere.
But WMO officials say the planetary average is expected to remain above 400 parts per million beginning in 2016.
“We will soon be living with globally averaged CO2 levels above 400 parts per million as a permanent reality,” Jarraud said.
