The concentration of carbon dioxide in the atmosphere reached the highest level recorded by modern instruments in April and is expected to rise further this month, according to scientists.
Carbon dioxide levels are expected to hit a new record in May, said Peter Tans, a senior scientist at the National Oceanic and Atmospheric Administration.
“It’s very concerning, very concerning,” he said. Not only is carbon dioxide high, but it’s rising faster and faster, he said.
“In the past decade, the growth rate has never been higher, and we are still on the same path,” Tans said. “So we’re going in the wrong direction, going as fast as we can.”
Carbon dioxide is the main driver of global warming, and it can remain in the atmosphere for hundreds of years.
Over the course of the year, carbon dioxide levels fluctuate as spring vegetation grows and then break down—a cycle known as Earth’s “breathing,” as shown by the swings in the carbon dioxide graph (above).
As a result of this annual cycle, carbon dioxide levels typically peak in April and May each year, when massive vegetation in the northern hemisphere is releasing carbon dioxide.
The longest continuous source for the modern record of carbon dioxide comes from the volcanic island of Mauna Loa in Hawaii, where geochemist Charles Keeling began making measurements in 1958.
The Mauna Loa data, also known as the “Keeling Curve” (shown as the gray wiggling line in the graph above), is considered one of the clearest evidence of human influence on the planet.
The total concentration of carbon dioxide in the atmosphere has surged in recent decades, causing global warming by about 1.1 degrees Celsius compared to pre-industrial levels.
“It’s a hallmark of all our human activity, primarily the burning of fossil fuels on Earth,” said Tim Renton, professor of climate change at the University of Exeter.
“Global warming has had all kinds of effects on the planet, and it has definitely changed the frequency and intensity of some extreme weather events,” Renton pointed to phenomena such as heat waves, forest fires and gradual sea level rise. .
In 2021, carbon dioxide emissions from energy will hit a record high as the global economy recovers from the pandemic.
The Earth itself typically absorbs about half of the carbon dioxide in the oceans and vegetation. However, the rest remains in the atmosphere, causing carbon dioxide concentrations to rise.
Recent research suggests that global warming may also be changing the Earth’s ability to absorb carbon dioxide.
Monitoring of carbon dioxide concentrations indicates that the degree or magnitude of seasonal variation is increasing. Penelope Pixar, a researcher at the University of East Anglia, said this suggests the Earth is taking in and releasing more carbon dioxide than before.
Rising carbon dioxide concentrations suggest it will be more difficult to meet targets set in the Paris climate agreement, which aims to limit global warming to well below 2 degrees Celsius, ideally 1.5 degrees Celsius.
“It’s troubling when we see carbon dioxide rising,” Pixar said. “Because it’s a reminder that time is running out.”