top of page
  • Jacob Bourne

Atmospheric CO2 Levels Reach Record High in May Despite Pandemic

Although the coronavirus pandemic’s onset resulted in over a year of reduced economic activity globally, the amount of carbon dioxide in Earth’s atmosphere is still rising. According to the Scripps Institution of Oceanography, the monthly average for May 2021 was 419 parts per million — much higher than the 350 ppm generally agreed as the safe upper limit for the atmospheric concentration of CO2.

Mauna Loa Observatory. Credit: NASA

The reading came from the National Oceanic and Atmospheric Administration’s Mauna Loa Baseline Observatory, where the practice of CO2 readings began in 1958. That year the CO2 reading was 316 ppm. While NOAA’s May 2021 average came in at 419.13 ppm, it was 417 ppm in May 2020. On two occasions in 2021 to date, Scripps recorded readings above 420 ppm.

The recent readings represent the highest concentrations of CO2 in Earth’s atmosphere since humans have been on the scene. About 4.1 million to 4.5 million years ago during the Pliocene when sea levels were about 78 feet higher than present and temperatures averaged 7 degrees Fahrenheit warmer than pre-industrial temperatures, CO2 was about 400 ppm.

It also demonstrates how current efforts to address climate change are vastly below the work required.

The reduced economic activity in 2020 brought on by pandemic-related shutdowns yielded a 7% drop in fossil fuel emissions since 2019, according to a report from the Stanford University School of Earth, Energy & Environmental Sciences. Although the fall is a historic one, it wasn’t enough to halt the march of escalating atmospheric CO2 concentrations.

"The ultimate control knob on atmospheric CO2 is fossil-fuel emissions,” said Scripps geochemist Ralph Keeling, who took over the Mauna Loa measurement series named the Keeling Curve. after his father’s death in 2005. “But we still have a long way to go to halt the rise, as each year more CO2 piles up in the atmosphere. We ultimately need cuts that are much larger and sustained longer than the COVID-related shutdowns of 2020.”

The problem is that CO2 is a long-lived gas that will linger in the atmosphere for centuries after it’s emitted, trapping solar radiation in the troposphere unless some other process removes it. Furthermore, the warming that has already occurred has spurred carbon emissions not directly tied to human activity, such as from worsening wildfire seasons, melting permafrost and methane bubbling up from Arctic lakes. This is in addition to the continued emissions from human activity such as transportation, manufacturing, agriculture and the portion of the electrical grid tied to fossil fuels.

“We are adding roughly 40 billion metric tons of CO2 pollution to the atmosphere per year,” said Pieter Tans, a senior scientist with NOAA’s Global Monitoring Laboratory. “That is a mountain of carbon that we dig up out of the earth, burn, and release into the atmosphere as CO2 – year after year. If we want to avoid catastrophic climate change, the highest priority must be to reduce CO2 pollution to zero at the earliest possible date."

The pandemic undoubtedly caused much suffering around the world, and what was a potential silver lining linked to the expected drop in emissions hasn’t amounted to much, as evidenced by the Mauna Loa readings. Yet, not taking dramatic and sustained and action to fight climate change will cause the G7 countries to lose almost $5 trillion per year over the next 30 years, according to Oxfam, as reported by Forbes. The loses will be due to the devastation brought on by increased natural disasters, drought, food and water shortages, desertification and sea-level rise, to name a few of climate change's effects.

Some action is being taken, including the development (albeit slow) of carbon capture and sequestration technologies, and the expansion of renewable energy sources. This year, the U.S. rejoiced the Paris Agreement. However, atmospheric CO2 levels continue to escalate as they have every year since the first measurement was taken.

“So far, most of these proposals are just vaporware,” said Tans. “The solution is right before our eyes. Solar energy and wind are already cheaper than fossil fuels, and they work at the scales that are required. If we keep stalling like we have done, then it will be too late.”

UPDATE, June 8, 2021, 10:17 p.m. PT: The article was updated to include the following: About 4.1 million to 4.5 million years ago during the Pliocene when sea levels were about 78 feet higher than present and temperatures averaged 7 degrees Fahrenheit warmer than pre-industrial temperatures, CO2 was about 400 ppm.


Drop a line to for newsletter subscriptions, tips, questions or comments.

bottom of page