Carbon dioxide just took an ominous, record-breaking jump

Researchers have recorded the largest jump in global average carbon dioxide emissions leading to a record level of climate-warming gases in the atmosphere. This unprecedented rise comes as the Earth has experienced its 11th month in a row of record-breaking temperatures and a string of climate change-fueled disasters.

“It's a new milestone and it helps reinforce the point that CO2 is still rising faster than ever overall in the atmosphere,” said Ralph Keeling, director of the CO2 Program at the University of California at San Diego’s Scripps Institution of Oceanography, which has tracked the gas at Mauna Loa Observatory since the 1950s.

In March, the monthly average concentration of carbon dioxide was 4.7 parts per million (ppm) higher than in March 2023, reaching a record 425.22 ppm. In the late 1950s when scientists first started tracking global CO2 concentrations, levels were at roughly 315 parts per million. Levels usually peak in spring owing to plants growing in the Northern Hemisphere, which pull the gas from the atmosphere over the summer. As of Thursday, they stood at 427.48 ppm.

CO2 makes a record annual jump

Multiple factors have contributed to the record rise. El Niño, the naturally occurring climate pattern that warms the eastern tropical Pacific, has been ongoing since last year. The change in ocean temperatures influences weather around the world, leading to drought in many parts of the tropics. The drought and heat that come with an El Niño event means that plants grow less, taking up less CO2 as a result. Increased wildfire activity also releases more CO2 into the atmosphere.

Burning fossil fuels is also a major driver. Emissions hit a peak last year, rising to 36.8 billion metric tons. That’s driven CO2 concentrations in the atmosphere higher, worsening a dizzying array of disasters, including heat waves, extreme rainfall, wildfires and floods, including amplifying some El Niño impacts.

“The emissions from the tropical forests are superimposed on these very large emissions from fossil fuel burning, which is bigger than ever,” says Keeling. “It's not that El Niño events are unusual, it's the fossil fuel burning is unusual in a historical sense. It's an extreme. It's never been higher.”

Keeling and his colleagues’ findings are based on data gathered at Hawaii’s Mauna Loa Observatory. There, Scripps has continuously monitored CO2 for decades, creating the world’s most detailed record of greenhouse gas concentrations. A November volcanic eruption of Mauna Loa briefly shut down observations, and the data from December 2022 through February 2023 was gathered at nearby Mauna Kea. Scripps said the data between the two sites aligns, giving researchers confidence in their findings.

Data from air samples pulled from ancient ice have found that CO2 levels hovered around 278 ppm before industrialization. Atmospheric concentrations of the gas likely haven’t been as high as they currently are in at least 3 million years. This year’s record increase comes as the world needs to rapidly cut emissions to avoid even worse impacts of climate change.