The cause of global warming is showing no signs of slowing as heat-trapping carbon dioxide in Earth’s atmosphere increased to record highs in its annual spring peak, jumping at one of the fastest rates on record, US officials have announced.
Carbon dioxide levels in the air are now the highest they’ve been in more than four million years because of the burning of oil, coal and gas. The last time the air had similar amounts was before human civilization took root, scientists said.
The US-based National Oceanic Atmospheric Administration announced that the carbon dioxide level measured in May in Hawaii averaged 424 parts per million. That’s three parts per million more than last year’s May average and 51 per cent higher than pre-industrial levels of 280 ppm.
It is one of the largest annual May-to-May increases in carbon dioxide levels on record, behind only 2016 and 2019, which had jumps of 3.7 and 3.4 parts per million.
“To me as an atmospheric scientist, that trend is very concerning,” said NOAA greenhouse gas monitoring group leader Arlyn Andrews.
“Not only is CO2 continuing to increase despite efforts to start reducing emissions, but it’s increasing faster than it was 10 or 20 years ago.”
Emissions used to increase by maybe one part per million per year, but now they are increasing at twice and even three times that rate, depending on whether there is an El Nino, Andrews said.
Sign up here to receive our daily newsletters and breaking news alerts, sent straight to your inbox. “The relentless rise in atmospheric CO2 is incredibly worrying if not wholly predictable,” said Brown University climate scientist Kim Cobb, who was not part of the research.
Carbon dioxide levels are rising so that each year is higher than the last. However, there’s a seasonal cycle with carbon dioxide so that it reaches its highest saturation point in May.
That’s because two-thirds of the globe’s land is in the northern hemisphere and plants suck carbon dioxide out of the air, so during late spring and summer carbon dioxide levels fall until they start rising again in November, Andrews said.
Carbon dioxide levels rise more during El Nino climate cycles because it is hotter and drier in the Tropics. An El Nino is brewing. That 3.0 increase may be a sign of an El Nino bump, she said.
