WMO reports alarmingly high CO2 concentrations, highlights urgent need for global climate action

The concentration of carbon dioxide (CO2) in the atmosphere is rising faster than ever, increasing by over 10% in just two decades.

Greenhouse gas levels have surged to record highs in 2023, according to the latest report from the World Meteorological Organization (WMO), which underscores the urgent need for global climate action. The concentration of carbon dioxide (CO2) in the atmosphere is rising faster than ever, increasing by over 10% in just two decades.

Throughout 2023, a combination of large vegetation fire emissions and a potential decrease in carbon absorption by forests, along with persistent fossil fuel emissions from human and industrial activities, contributed to this alarming trend. The WMO’s annual Greenhouse Gas Bulletin reported that global CO2 concentrations reached 420.0 parts per million (ppm), while methane (CH4) and nitrous oxide (N2O) concentrations rose to 1,934 parts per billion (ppb) and 336.9 ppb, respectively. These figures represent 151%, 265%, and 125% of pre-industrial levels (before 1750).

“Another year. Another record. This should set alarm bells ringing among decision-makers. We are clearly off track to meet the Paris Agreement goal of limiting global warming to well below 2°C, and aiming for 1.5°C above pre-industrial levels,” stated WMO Secretary-General Celeste Saulo. “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 increase of CO2 in 2023 marked the 12th consecutive year of rising levels greater than 2 ppm, though the annual increase of 2.3 ppm was higher than in 2022. Since 2004, CO2 levels have increased by 11.4%, or 42.9 ppm. The WMO Greenhouse Gas Bulletin is a key publication that informs the UN Climate Change Conference (COP) and is now in its 20th issue.

The report highlights that approximately half of CO2 emissions remain in the atmosphere, while over 25% are absorbed by the oceans, and nearly 30% by land ecosystems. However, there is considerable year-to-year variability due to natural phenomena such as El Niño and La Niña.

WMO Deputy Secretary-General Ko Barrett warned of a vicious cycle that could arise from natural climate variability. As climate change progresses, ecosystems may begin to emit more greenhouse gases. For example, wildfires could release additional CO2, while warmer oceans might absorb less, leading to further increases in atmospheric CO2 and accelerated global warming.

From 1990 to 2023, the warming effect on the climate from long-lived greenhouse gases—known as radiative forcing—increased by 51.5%, with CO2 accounting for approximately 81% of this rise, according to the National Oceanic and Atmospheric Administration (NOAA) Annual Greenhouse Gas Index.

The persistence of CO2 in the atmosphere means that temperatures already observed will continue for decades, even with rapid reductions in emissions. The last time atmospheric CO2 concentrations were comparable was 3-5 million years ago, a period when temperatures were 2-3°C warmer and sea levels were 10-20 meters higher than they are today.

The findings of the WMO report come at a critical time as nations prepare for COP29 in Baku, Azerbaijan, where discussions on climate action will intensify. With the increasing urgency surrounding climate change, the world faces a pressing need to adopt comprehensive strategies that not only aim to reduce emissions but also enhance the resilience of natural systems and communities.