Carbon-Dioxide Level in Atmosphere Hits Historical High

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Matt Beasley

May 16, 2022, 5:31:11 PMMay 16
Carbon-Dioxide Level in Atmosphere Hits Historical High
By Nidhi Subbaraman, May 5, 2022, WSJ

The level of CO2 in the atmosphere rose to a record in April,
according to measurements of the heat-trapping gas at an observatory
high on Hawaii’s Mauna Loa volcano. The level during the month
averaged 420 parts per million, scientists said Thursday.

“This is the highest we’ve ever seen” since contemporaneous
monitoring of atmospheric CO2 began 64 years ago, Pieter Tans,
a senior scientist at the National Oceanic and Atmospheric
Administration’s Global Monitoring Lab in Boulder, Colo., said
of the record. The past record at Mauna Loa was set last May,
at 419 parts per million.

The uptick is part of a continuing decadeslong rise in atmospheric
CO2 levels driven by the burning of coal and other fossil fuels,
according to the chemical fingerprinting of atmospheric carbon
atoms and various other scientific analyses conducted in recent years.

The rising levels of carbon dioxide—and the rising global temps
to which they are linked—indicate that efforts to rein in carbon
emissions are falling short. “Folks, we’re still full speed on the
wrong track,” Dr. Tans said.

Emissions from the burning of coal, oil and natural gas for energy
sent 36.3 billion metric tons of CO2 into the atmosphere in 2021,
according to the International Energy Agency.

“To mitigate the impacts of climate change, we need to get to
net-zero emissions and halt the increase in concentrations” of CO2,
said Noelle Selin, an atmospheric chemist at M.I.T. “What the increase
in concentrations is telling you is that we’re not there yet.”

Nearly 12,000 feet above sea level and isolated in the Pacific,
the Mauna Loa observatory is an ideal monitoring site because of
its remoteness from both emission sources and carbon-absorbing
forests, Dr. Tans said. It is one of four NOAA locations where
carbon-dioxide levels are measured as part of an effort to gauge
global levels of the gas. The other locations are in Alaska,
Antarctica and American Samoa.

Scientists have logged carbon-dioxide readings every hour on Mauna Loa
since 1958, when the American atmospheric scientist Charles Keeling
began tracking the gas. Levels registered at 313 parts per million
in March 1958—not far above the preindustrial level of about 280 parts
per million—have risen sharply since then.

“Every single year in these 64 years, the CO2 went up from one year
to the next,” Dr. Tans said.

The graph showing the rise in annual levels of CO2, dubbed the
Keeling Curve for Charles Keeling’s landmark measurements, has a
signature saw-toothed pattern that reflects seasonal fluctuations
in atmospheric carbon dioxide.

Levels drop in summer in the Northern Hemisphere, as plants absorb
the gas, and then start rising again in the fall and winter months
through the spring. Dr. Tans said the carbon-dioxide level is likely
to be even higher at the end of the month, as May is typically when
levels are highest.

“In 2013 or so we crossed the 400 threshold, and now we’re crossing
420,” said Ralph Keeling, a Scripps Institution of Oceanography
geochemist and the son of Charles. “You can see that we’re going
to rocket on upward past 430, past 440. It’s really hard to imagine
this thing coming into check before we get into the high 400s.”
The April record was corroborated by Dr. Keeling, who now leads
the monitoring program his father began in the 1950s.

The last time atmospheric CO2 levels were so high occurred over
2.5 million years ago, analyses of fossils and minerals suggest.
CO2 levels at that time are believed to have exceeded 400 ppm.

Global leaders have repeatedly pledged to reduce emissions at
international summits, most recently in November in Glasgow,
Scotland. But recent research suggests that efforts are falling
short of targets established by the Paris Agreement, a major
climate pact signed by 190 nations in 2015.

“Increasing atmospheric concentrations suggest that we are not
heading in the right direction” toward the Paris targets, said
David Waskow, director of the International Climate Initiative
at the World Resources Institute, a global nonprofit.

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