Global average CO2 concentrations jumped by a record 3.5 parts per million in 2024, reaching 423.9 ppm, according to the World Meteorological Organization. This marks the largest annual increase since measurements began in 1957. The surge is attributed to fossil fuel emissions, wildfires, and reduced carbon uptake by lands and oceans.
The World Meteorological Organization (WMO) reported that between 2023 and 2024, atmospheric CO2 levels rose by 3.5 ppm to 423.9 ppm, surpassing the previous year's increase of 2.3 ppm and representing the biggest jump since records started in 1957. This acceleration continues a trend where annual growth rates have tripled since the 1960s, with concentrations now at levels not seen since 3 to 5 million years ago.
Key factors driving the rise include persistent high emissions from fossil fuels, increased emissions from wildfires, and a notable decline in carbon absorption by the planet's lands and oceans. The 2024 El Niño event exacerbated this by raising global temperatures, leading to heat, fires, and drought in regions like the Amazon, where tropical forest loss doubled compared to 2023.
"The heat trapped by CO2 and other greenhouse gases is turbocharging our climate and leading to more extreme weather," said Ko Barrett at the WMO. Experts note that while reduced uptake during El Niño years is expected, there are signs of a longer-term weakening, particularly in the land sink outside tropical areas. "There has been some suggestions that the land sink was particularly low in 2023 and 2024, even for El Niño years, and that there has been a worrying reduction over time, particularly in the northern hemisphere outside the tropics," said Zeke Hausfather, a climate scientist at the Breakthrough Institute. He added, "In short, there are worrying signs that the land sink in particular is declining, but it’s too early to know with confidence without another few years of data."
"It is normal for some tropical lands to be drier and store less carbon during warm El Niño years such as 2024," noted Richard Allan at the University of Reading, UK. Piers Forster at the University of Leeds emphasized the urgency: "The biggest reason for the ongoing increase [in CO2 concentrations] is fossil fuel emissions being at a persistent all-time high and not yet coming down." The WMO warns that excess CO2 will warm the planet for centuries, intensifying climate impacts.