For the first time on record, monthly average CO2 levels exceeded 430 parts per million (ppm), according to experts at Scripps Institution of Oceanography in San Diego.
The experts’ new measurements come from Mauna Loa Observatory, a research station situated high on the slopes of the Mauna Loa volcano, Hawaii.
However, CO2 concentrations have not yet passed the 430 ppm mark in the Southern Hemisphere, which has a reversed cycle.
In 1958, he began monitoring CO2 concentrations at Mauna Loa Observatory and documented a long-term increase, known as the Keeling Curve.
NOAA’s Global Monitoring Laboratory, meanwhile, begun daily CO2 measurements in 1974 and has maintained a complementary, independent measurement record ever since.
Scientists have discovered that the amount of carbon dioxide (CO2) in the atmosphere is higher now than it has ever been.
Monthly average CO2 levels topped 430 parts per million (ppm) for the first time in history, according to scientists at Scripps Institution of Oceanography in San Diego.
The highest level since precise measurements started 67 years ago was reached by the May 2025 monthly average, which was 430 point 2 ppm.
Global warming, which could eventually make the Earth’s surface too hot for people, is accelerating with increasing CO2 levels in the atmosphere.
Additionally, CO2 can cause a number of health problems at much higher concentrations.
This is concerning because it can result in cognitive decline, fatigue, nausea, and in the worst situations, death.
The Scripps CO2 Program director, Ralph Keeling, declared, “Another year, another record.”.
It’s sad, he continued. “.”.
CO2 traps heat and warms the lower atmosphere, much like other greenhouse gases.
Extreme events like heat waves, droughts, wildfires, heavy rains, and flooding are exacerbated by this alteration in weather patterns.
Additionally, rising CO2 levels contribute to ocean acidification, which hinders the growth of hard skeletons or shells for marine organisms like coral and crustaceans.
The new measurements by the experts are from Mauna Loa Observatory, a research facility located high on the slopes of Hawaii’s Mauna Loa volcano.
At 11,141 feet above sea level, Mauna Loa Observatory uses various forms of light and radiation to measure the various gases in the air.
The experts say that the monthly average for May 2025 at the observatory is 430.2 ppm, which is 3.5 ppm higher than the measurement for May 2024, which was 426.7 ppm.
Meanwhile, an independent report from NOAA’s Global Monitoring Laboratory in Boulder, Colorado, shows an average of 430.5 ppm, which is 3.6 ppm higher than the previous year.
WFLA Tampa Bay’s climate specialist and meteorologist, Jeff Berardelli, described the new record as “concerning” in a post on X.
The most prevalent greenhouse gas produced by humans is CO2, which can linger in the atmosphere and seas for thousands of years.
A period of time known as the “Pliocene Climatic Optimum” occurred between 4 and 5 million years ago, and scientists estimate that the amount of carbon in the Earth’s atmosphere today is equivalent to that amount.
The average global temperature was 7°F (3point 9°C) higher than it was prior to the Industrial Revolution, and the sea level was an astounding 78 feet (24 meters) higher than it is today.
In actuality, the temperature was so high during this time that vast forests covered parts of the Arctic that are now chilly, desolate tundra.
Even though human activity emits CO2 continuously throughout the year, the Northern Hemisphere experiences its highest levels of atmospheric CO2 in the spring, specifically in May.
As a large portion of the plant matter in the hemisphere breaks down between autumn and spring, CO2 is released into the atmosphere.
The highest amount of CO2 in the atmosphere occurs in May, just before plants begin to grow and absorb CO2.
This initiates the process of reducing atmospheric CO2 levels until the autumn, when the plants begin to die, and the cycle repeats.
Scientists say the new measurements from Mauna Loa Observatory show the average level of CO2 in the Northern Hemisphere’s atmosphere.
However, in the Southern Hemisphere, where the cycle is reversed, CO2 concentrations have not yet surpassed 430 parts per million.
Charles David Keeling, a Scripps scientist and Ralph Keeling’s father, was the first to realize that the Northern Hemisphere’s CO2 levels peaked in May.
He started keeping an eye on CO2 levels at Mauna Loa Observatory in 1958 and recorded a sustained rise that became known as the Keeling Curve.
In contrast, NOAA’s Global Monitoring Laboratory started measuring CO2 on a daily basis in 1974 and has since kept an independent, complementary measurement record.
