Astana (Web Desk/Agencies): The atmospheric concentration of carbon dioxide has reached an unprecedented level of 430.2 parts per million (ppm), a figure that scientists believe has not been observed on Earth for millions of years.
This latest data, recorded in May 2025, comes from the Mauna Loa Observatory in Hawaii, a facility operated by the National Oceanic and Atmospheric Administration (NOAA), with measurements also conducted by researchers from the Scripps Institution of Oceanography at the University of California, San Diego.
This year’s reading represents a significant increase of 3.5 ppm from the previous May, when atmospheric CO₂ stood at 426.7 ppm.
The continual rise is directly linked to the combustion of fossil fuels, a process that remains the dominant source of human-caused emissions and is increasingly contributing to large-scale disruption of Earth’s climate systems.
The Scripps Institution notes that this ongoing elevation in CO₂ levels is a driving force behind a growing range of extreme climate events.
These include heatwaves of greater intensity and frequency, prolonged periods of drought, as well as heightened rainfall leading to more severe flooding. Such changes are placing added stress on ecosystems and human societies alike.
Alongside changes in atmospheric dynamics, elevated carbon dioxide is also altering ocean chemistry. As CO₂ dissolves into seawater, it triggers acidification processes that reduce the availability of carbonate ions—essential building blocks for marine organisms like corals and shellfish.
This hampers their ability to construct calcium carbonate structures, posing a serious threat to marine biodiversity and the integrity of ocean ecosystems.
Although Mauna Loa remains the primary global reference point for tracking long-term CO₂ trends, it does not fully reflect regional or hemispheric variations.
For example, in the Southern Hemisphere, where seasonal patterns differ, some observatories have yet to record levels as high as 430 ppm.
Still, observations from diverse geographic locations are integrated into the Global Greenhouse Gas Reference Network, an international system that informs climate science and policy development.
Earlier, Kazinform News Agency reported on a session at the Astana International Forum, where speakers addressed the urgent need to accelerate climate action while ensuring that the benefits of such efforts are shared equitably across societies.