Carbon dioxide levels in the atmosphere just hit a ‘depressing’ new record | These data come from the National Oceanic and Atmospheric Administration’s Mauna Loa Observatory, which may soon be shut down because of proposed government budget cuts

The amount of carbon dioxide detected in the atmosphere hit a record high in April. CO2 levels averaged about 431 parts per million (ppm) over that month, according to data collected at the National Oceanic and Atmospheric Administration’s Mauna Loa Observatory in Hawaii.

The Mauna Loa Observatory has been directly observing atmospheric CO2 and keeping record of its levels for the longest out of any other U.S. facility. Mauna Loa first began keeping track of the gas’s presence in the atmosphere in 1958. That year the April level of CO2 was under 320 ppm.

The record comes as the observatory faces the risk of having its funding cut. A budget proposal on NOAA’s website for the 2027 fiscal year, which begins in October 2026, proposes cutting funding to numerous climate monitoring facilities, including Mauna Loa.

Although the amount of CO2 in the atmosphere has continued to rise, there was a reduction in U.S. emissions in 2023 and 2024. That trend, however, was reversed in 2025, at least partially because of the increased electricity demand from artificial intelligence data centers.

Still, Labe says there are reasons for optimism as the use of renewable energy sources such as solar and wind expands.