HONOLULU (KHON2) — Carbon dioxide, or CO2, is now more than 50% higher than pre-industrial levels, according to the National Oceanic and Atmospheric Administration (NOAA).

CO2 is measured at NOAA’s Mauna Loa Atmospheric Baseline Observatory on the Big Island, and this year, it peaked at 421 parts per million. This hasn’t been seen for millions of years.

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Scientists from NOAA and Scripps Institution of Oceanography at the University of California San Diego said the “relentless increase” of CO2 measured at Mauna Loa is a stark reminder that we need to take urgent steps to become a more “Climate Ready Nation.”

CO2 pollution is created by burning fossil fuels for transportation, electrical generation, deforestation and other practices. This traps heat radiating from Earth’s surface and causes the planet to warm steadily, resulting in a domino effect of extreme heat, drought and wildfire activity, flooding and tropical storms.

NOAA adds that greenhouse gas pollution can worsen these effects by increasing sea surface temperatures and the absorption of carbon, which makes the ocean more acidic. As a result, ocean deoxygenation happens, making it harder for marine organisms to survive.

“Carbon dioxide is at levels our species has never experienced before — this is not new,” Pieter Tans, senior scientist with the Global Monitoring Laboratory, said in the announcement on June 3. “We have known about this for half a century, and have failed to do anything meaningful about it. What’s it going to take for us to wake up?” 

CO2 levels were consistently around 280 ppm for almost 6,000 years of human civilization before the Industrial Revolution, according to NOAA, and since then, an estimated 1.5 trillion tons of CO2 pollution have been generated. The atmosphere will continue to warm.


NOAA’s observatory sits on the slopes of the volcano at an elevation of 11,141 feet above sea level. It samples air undisturbed by local pollution or vegetation, producing measurements that represent the average state of the atmosphere in the Northern Hemisphere.

In 1958, a scientist with the Scripps Institution of Oceanography initiated on-site measurements of CO2 at NOAA’s weather station on Mauna Loa. Charles David Keeling was the first to recognize that despite the seasonal fluctuation, CO2 levels were rising every year.

In 1974, NOAA began measurements, and the two research institutions have been making independent observations since then. Keeling’s son, geochemist Ralph Keeling, runs the Scripps program at Mauna Loa.

Th data that comes from the Mauna Loa observatory is added to the Global Greenhouse Gas Reference Network, which international climate scientists use, as well as policymakers attempting to address the causes and impacts of climate change.

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