Greenhouse gas levels hit a new record high in 2023: World Meteorological Organization

The increase in CO2 between 2022 and 2023, WMO said, was slightly higher than the 2021-2022 period but slightly lower than the average annual growth rate over the last decade, and was partly caused by natural variability. CO2 emissions caused by large vegetation fires and a possible reduction in carbon absorption by forests combined with stubbornly high fossil fuel CO2 emissions from human and industrial activities drove the CO2 increase in 2023, according to WMO’s annual Greenhouse Gas Bulletin.

The El Nino weather phenomenon, which leads to warmer weather and reduced rainfall, especially in South Asia, caused record high temperatures, drier vegetation and wildfires, thus releasing more GHGs into the earth. “During El Nino years, greenhouse gas levels tend to rise because drier vegetation and forest fires reduce the efficiency of land carbon sinks,” said the WMO, a specialised agency of the United Nations whose mandate covers weather, climate and water resources.

WMO scientists warned that the rising CO2 concentration and its impact on climate change could cause the natural ecosystems to become sources of greenhouse gases. “The bulletin warns that we face a potential vicious cycle. Natural climate variability plays a big role in carbon cycle. But in the near future, climate change itself could cause ecosystems to become larger sources of greenhouse gases. Wildfires could release more carbon emissions into the atmosphere, whilst the warmer ocean might absorb less CO2,” said WMO deputy secretary-general Ko Barrett.

She added, “Consequently, more CO2 could stay in the atmosphere to accelerate global warming. These climate feedbacks are critical concerns to human society.”

From 1990 to 2023, radiative forcing—the warming effect on our climate—by long-lived greenhouse gases increased by 51.5 per cent, with CO2 accounting for about 81 per cent of this increase, according to the National Oceanic and Atmospheric Administration Annual Greenhouse Gas Index cited in the WMO Bulletin.

The WMO said that given the extremely long life of CO2 in the atmosphere, even if emissions reduce rapidly due to net zero targets, the observed temperature levels will persist for several decades.

It also pointed out that climate feedback concerns were not limited to CO2 alone. Methane present in the earth’s atmosphere saw the largest three-year increase between 2020 and 2022. Observations and model simulations pointed to a rise in methane emissions from natural wetlands in response to warmer temperatures and particularly wetter land conditions during the 2020-2022 La Nina conditions.