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Carbon dioxide measured at NOAA’s Mauna Loa Atmospheric Baseline Observatory reached a new peak for 2022, pushing the atmosphere further into territory not seen for nearly 4 million years, federal scientists announced Friday. 

NOAA’s measurements of carbon dioxide at the mountaintop observatory on Hawaii’s Big Island averaged 420.99 parts per million (ppm), an increase of 1.8 ppm over 2021.

Meanwhile, scientists at Scripps Institute of Oceanography at the University of California San Diego, which maintains an independent record, calculated a monthly average of 420.78 ppm. 

“The science is irrefutable: humans are altering our climate in ways that our economy and our infrastructure must adapt to,” said NOAA Administrator Rick Spinrad, Ph.D. “We can see the impacts of climate change around us every day. The relentless increase of carbon dioxide measured at Mauna Loa is a stark reminder that we need to take urgent, serious steps to become a more Climate Ready Nation.” 

CO2 pollution is generated by burning fossil fuels for transportation and electrical generation, by cement manufacturing, deforestation, agriculture and many other practices.

Along with other greenhouse gases, CO2 traps heat radiating from the planet’s surface that would otherwise escape into space, causing the planet’s atmosphere to warm steadily, which unleashes a cascade of weather impacts, including episodes of extreme heat, drought and wildfire activity, as well as heavier precipitation, flooding and tropical storm activity.   

Impacts to the world’s oceans from greenhouse gas pollution include increasing sea surface temperatures, rising sea levels, and an increased absorption of carbon, which makes sea water more acidic, leads to ocean deoxygenation, and makes it more difficult for some marine organisms to survive.

Prior to the Industrial Revolution, CO2 levels were consistently around 280 ppm for almost 6,000 years of human civilization.

Since then, humans have generated an estimated 1.5 trillion tons of CO2 pollution, much of which will continue to warm the atmosphere for thousands of years. 

CO2  levels are now comparable to the Pliocene Climatic Optimum, between 4.1 and 4.5 million years ago, when they were close to, or above 400 ppm.

During that time, sea levels were between 5 and 25 meters higher than today, high enough to drown many of the world’s largest modern cities. Temperatures then averaged 7 degrees Fahrenheit higher than in pre-industrial times, and studies indicate that large forests occupied today’s Arctic tundra.

This graph shows the monthly mean carbon dioxide measured at Mauna Loa Observatory, Hawaii, the longest record of direct measurements of CO2 in the atmosphere. (NOAA Global Monitoring Laboratory, Scripps Institute of Oceanography at the University of California San Diego. )

NOAA’s observatory, situated high on the slopes of the Mauna Loa volcano, is the global benchmark location for monitoring atmospheric CO2.

At an elevation of 11,141 feet above sea level, the observatory samples air undisturbed by the influence of local pollution or vegetation, and produces measurements that represent the average state of the atmosphere in the northern hemisphere. 

The Mauna Loa data, together with measurements from sampling stations around the world, are incorporated by NOAA’s Global Monitoring Laboratory into the Global Greenhouse Gas Reference Network, a foundational research dataset for international climate scientists and a benchmark for policymakers attempting to address the causes and impacts of climate change.

To visualize how sea level rise may affect your community, visit NOAA’s sea level rise viewer, at: https://coast.noaa.gov/slr/.