During a year of extremes, carbon dioxide levels surge faster than ever

Carbon dioxide is accumulating in the atmosphere faster than ever—accelerating on a steep rise to levels far above any experienced during human existence, scientists from NOAA and the Scripps Institution of Oceanography ...
Levels of carbon dioxide (CO2) measured at NOAA's Mauna Loa Atmospheric Baseline Observatory by NOAA's Global Monitoring Laboratory surged to a seasonal peak of just under 427 parts per million (426.90 ppm) in May, when CO2 reaches its highest level in the Northern Hemisphere.

That's an increase of 2.9 ppm over May 2023 and the 5th-largest annual growth in NOAA's 50-year record. When combined with 2023's increase of 3.0 ppm, the period from 2022 to 2024 has seen the largest two-year jump in the May peak in the NOAA record.

CO2 measurements sending ominous signs
Scientists at Scripps, the organization that initiated CO2 monitoring at Mauna Loa in 1958 and maintains an independent record, calculated a May monthly average of 426.7 ppm for 2024, an increase of 2.92 ppm over May 2023's measurement of 423.78 ppm. For Scripps, the two-year jump tied a previous record set in 2020.

From January through April, NOAA and Scripps scientists said CO2 concentrations increased more rapidly than they have in the first four months of any other year. The surge has come even as one highly regarded international report has found that , the main driver of climate change, have plateaued in recent years.

Atmospheric carbon dioxide measured at NOAA’s Mauna Loa Atmospheric Baseline Observatory peaked in May 2024 at a monthly average of 426.9 parts per million, establishing another high mark in the 66-year record of observations on the Hawaiian volcano, according to scientists from NOAA and Scripps Institution of Oceanography at the University of California San Diego. (2019 photo of observatory grounds on the Big Island of Hawaii.). Credit: Susan Cobb/NOAA Research
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This graph shows the full record of monthly mean carbon dioxide measured at Mauna Loa Observatory, Hawaii. The carbon dioxide data on Mauna Loa constitute the longest record of direct measurements of CO2 in the atmosphere. They were started by C. David Keeling of the Scripps Institution of Oceanography in March of 1958 at the NOAA Weather Station on Mauna Loa volcano. NOAA started its own CO2 measurements in May of 1974, and they have run in parallel with those made by Scripps since. Credit: NOAA Global Monitoring Laboratory
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These graphs compare the rise of atmospheric carbon dioxide (CO2) in Mauna Loa and global records.The decadal average rate of increase of CO2 in the graphs on the right are depicted by the black, horizontal lines. Credit: NOAA Global Monitoring Laboratory
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