Planet-warming pollution in Earth’s atmosphere last year hit the highest levels in human history, scientists announced Monday – a worrying indicator of the world’s failure to curb climate change as global temperatures are on track to hit yet another record high.

Concentrations of carbon dioxide – the most important driver of global warming – are now growing faster than at any time since our species evolved, according to the World Meteorological Organization’s annual Greenhouse Gas Bulletin. The increase can be traced back to stubbornly high rates of fossil fuel consumption, the report said, as well as ecosystems that are becoming more likely to produce emissions and potentially less capable of absorbing excess carbon.

Levels of the potent greenhouse gases methane and nitrous oxide also hit all-time highs in 2023, the WMO said. The total heat-trapping potential of the atmosphere is now 51.5% higher than in 1990, when United Nations scientists first warned the world was on track for catastrophic climate change.

Steam billows from a coal-fired power plant in 2021, in Craig, Colo. Rick Bowmer/Associated Press, file

“This should set alarm bells ringing among decision makers,” WMO Secretary General Celeste Saulo said in a statement. “Every part per million and every fraction of a degree temperature increase has a real impact on our lives and our planet.”

For the past 14 months, global temperatures have been at least 2.7 degrees Fahrenheit higher than preindustrial levels, according to Europe’s top climate agency. In a report last week, U.N. researchers said nations must cut greenhouse house emissions to 42% below 2019 levels to avoid permanently exceeding that threshold and triggering the most dangerous consequences of global warming.

But Monday’s Greenhouse Gas Bulletin shows the world is nowhere near achieving that target.

Drawing on data from hundreds of measurement stations spread across more than 80 countries and all the world’s ocean basins, the report found that atmospheric levels of heat-trapping gases have grown at an accelerating rate in the past decade.

The concentration of carbon dioxide in Earth’s atmosphere last year exceeded 420 parts per million – a level not seen since the Pliocene Epoch more than 3 million years ago. At that time, global temperatures were 3.6 to 5.4 degrees Fahrenheit warmer, sea levels were 30 to 60 feet higher, and Homo sapiens did not yet exist.

Most of the recent growth comes from people burning coal, oil and gas, the report said. But the WMO researchers also found worrying evidence that human-driven warming has caused natural systems to release more greenhouse gases and may be hurting the Earth’s ability to absorb what people emit.

The hike in carbon dioxide concentrations last year coincided with the largest-observed spike in carbon monoxide – a related gas that is produced when trees burn, the scientists said. Global carbon emissions from forest fires were 16% above average during the 2023-2024 fire season, as Australia endured a historic drought and Canada saw a record 37 million acres of forest go up in flames.

Surging levels of methane may also be traced to degraded ecosystems, data suggests. Chemical analysis of the gas, which traps 28 times more heat than carbon dioxide over a 100-year time frame, suggests that it is increasingly coming from microbial activity, rather than fossil fuel burning. Though some of that increase can be attributed to bacteria living in landfills and the guts of cows, researchers worry it is also being produced by warming tropical wetlands and thawing Arctic permafrost.

Meanwhile, the net amount of carbon taken up by ecosystems last year was about 28% lower than in 2021 and 2022, according to data from the National Oceanic and Atmospheric Administration’s Global Monitoring Laboratory. This decline may be in part because of 2023’s record-high temperatures, which are known to stress plants and cut into ecosystems’ ability to serve as a carbon sink.

The more the world continues to warm, the researchers said, the more natural carbon sinks will weaken, and the harder it will be to achieve the world’s climate goals.

“We face a potential vicious cycle,” WMO Deputy Secretary General Ko Barrett said in a statement. “These climate feedbacks are critical concerns to human society.”