Another 'extremely worrisome' climate change record set

The world set a new record this week for the highest daily level of carbon dioxide in the atmosphere, another grim marker signaling that the greenhouse gas emissions that cause climate change continue are continuing at a dangerous pace.

On May 11, the Scripps Institute of Oceanography at the University of California, San Diego, measured 421.37 parts per million of carbon dioxide in the Earth's atmosphere, besting the previous record of 418.95 ppm set in May 2021.

The new daily record comes after April recorded the a new average monthly record of 410 ppm of atmospheric CO2 for the first time in recorded history.

"It is very concerning, extremely worrisome," Peter Tans, senior climate scientist at NOAA, told the Financial Times. "This last decade, the rate of increase has never been higher, and we are still on the same path. We're going in the wrong direction at maximum speed."

Researchers at National Oceanographic and Atmospheric Administration (NOAA) say they expect that May will set a monthly average record.

“This also represents a 30-percent increase in carbon dioxide concentration in the global atmosphere since the Keeling Curve began in 1958,” the Scripps Institute said on its website of the April milestone.

The Keeling Curve is named after Dr. Charles David Keeling, who started measuring carbon dioxide concentrations in the atmosphere in 1956. Taking regular air samples, he noticed a pattern whereby the air contained higher concentrations of CO2 at night than during the day, hence presenting a saw-tooth pattern over time. He attributed the daily peaks and valleys to photosynthesis and plant respiration. Seasonal patterns also emerged over time, with CO2 levels peaking during springtime and falling in autumn in response to plant growing cycles.

The measurement of atmospheric carbon dioxide through 2019. (Scripps Institute)
The measurement of atmospheric carbon dioxide through 2019. (Scripps Institute of Oceanography)

As years’ worth of measurements were compiled, Keeling was able to show that the atmospheric concentration of CO2 was rising. He was able to connect that rise to the burning of fossil fuels. That greater concentration of atmospheric CO2, countless studies have shown, results in what is known as the greenhouse effect, causing global temperatures to rise.

After dipping during the start of the coronavirus pandemic due to a sudden decrease in driving, airplane travel and economic activity, global greenhouse emissions rebounded in 2021. Unless emissions are significantly curbed, the world has roughly a 50-50 chance of seeing global temperature rise 1.5°C above pre-industrial levels in the next five years, a report released this week by the Met Office, the meteorological service for the United Kingdom, concluded.

“The chance of at least one year exceeding 1.5°C above pre-industrial levels between 2022-2026 is about as likely as not (48%). However, there is only a very small chance (10%) of the five-year mean exceeding this threshold,” the report said.

The Scripps Institute notes one its website that the amount of CO2 in the atmosphere will help decide just how high average global temperatures will rise above pre-industrial levels.

“A recent authoritative report concluded that a level of CO2 between 370 and 540 ppm has a 66 percent probability of keeping the world within this 2ºC limit on warming, with a best estimate of 430 ppm,” the authors wrote. “There is also a time lag for the global temperature to catch up with the CO2 that humans have already added to the atmosphere, so temperatures will continue to rise for many years after the atmospheric CO2 amount is stabilized. Plus, we aren’t sure that limiting warming to 2°C is ‘safe,’ at least not for everyone on the planet.”