GENEVA (AN) — Concentrations of carbon dioxide in Earth's atmosphere, one of the most reliable indicators of human-caused climate change, is at another record high – after rising 11.4% in just two decades.
It's an alarming sign the world is nowhere close to taking effective action against the dangerous impacts of present and future climate change.
Carbon emissions from huge wildfires, a possible reduction in the amount of carbon that forests absorb, and "stubbornly high fossil fuel CO2 emissions from human and industrial activities" drove the increase last year, the World Meteorological Organization says.
What's new: Globally-averaged surface concentration of CO2 reached 420.0 parts per million (ppm), or 151% higher than pre-industrial levels, WMO reported in its annual Greenhouse Gas Bulletin on Monday.
The 2023 increase of CO2 in the atmosphere was higher than that of 2022, but it was lower than that of the three years before, according to WMO. The annual increase of 2.3 ppm was the 12th consecutive year with an increase of more than 2 ppm.
This year's atmospheric CO2 level is 11.4 %, or 42.9 ppm, above the level of 377.1 ppm recorded in 2004 by WMO’s Global Atmosphere Watch network of monitoring stations.
Some of this is attributable to naturally occurring phenomena like El Niño and La Niña. During El Niño years, greenhouse gas levels tend to rise when drier vegetation and forest fires lessen the ability of land to absorb carbon.
Almost 30% of all CO2 emissions are absorbed by land ecosystems, and a little more than a quarter are taken up by the ocean; the rest remains in the atmosphere.
Why it's reliable: The measurements are based on long-term observations within the Global Atmosphere Watch network of monitoring stations. Just 15 years ago, CO2 concentrations were hovering around 385 ppm at Hawaii's Mauna Loa Observatory, a government-run facility.
In 1958, climatologist Charles David Keeling pioneered the measurement of CO2 in the atmosphere, installing his experimental manometer on the Hawaiian volcano because the trade winds there had some of the cleanest air on the planet.
What's next: “Another year. Another record. This should set alarm bells ringing among decision makers," says WMO Secretary-General Celeste Saulo, an Argentine meteorologist.
"We are clearly off track to meet the Paris Agreement goal of limiting global warming to well below 2° Celsius and aiming for 1.5° above pre-industrial levels," she says. "These are more than just statistics. Every part per million and every fraction of a degree temperature increase has a real impact on our lives and our planet."
The measurements are used to inform leaders and negotiators headed to the U.N. climate summit, COP29, next month in Baku, Azerbaijan. Nations are far off-track from fulfilling their commitments to lower greenhouse gas emissions under the 2015 Paris Agreement.
The 2024 edition of U.N. Environment Program’s Emissions Gap Report last week showed that emissions must fall 42% by 2030, compared with 2019 levels, to fulfill the Paris treaty's preferred threshold of 1.5°.
Emissions must fall 28% by 2030, compared with 2019 levels, to stick to the 2° target. By 2035, emissions must decrease 57% for the 1.5° target, and 37% for 2°.
