The National Oceanic and Atmospheric Administration in 2023 measured levels of carbon dioxide in the atmosphere that haven't been as high for millions of years.
Atmospheric CO2 reached an average of 424 parts per million in May, an increase of 3 parts per million over the same time last year.
NOAA says this is the fourth steepest single-year climb it has on record.
CO2 levels are now more than 50% higher than they were at the start of the industrial revolution.
NOAA got its measurements this year from a temporary site at the top of Mauna Kea in Hawaii, because lava flows on Mauna Loa cut off access to its usual instruments. In November of 2022, lava from the erupting volcano disrupted power transmission and rendered more than a mile of access road impassable. It's only the second time in 60 years that a lava flow has interrupted monitoring.
Biden administration announces new funding to speed up carbon capture
The government wants to help carbon capture along so that it becomes more appealing for businesses.
The CO2 emitted from burning fossil fuels and other industrial processes traps heat in Earth's atmosphere and contributes to the amplified effects of wildfires, flooding and other extreme weather. The greenhouse gas also increasingly threatens the world's oceans, where it threatens ecosystems with increased temperatures and acidified seawater.
"Every year we see carbon dioxide levels in our atmosphere increase as a direct result of human activity," NOAA Administrator Rick Spinrad said. "Every year, we see the impacts of climate change in the heat waves, droughts, flooding, wildfires and storms happening all around us. While we will have to adapt to the climate impacts we cannot avoid, we must expend every effort to slash carbon pollution and safeguard this planet and the life that calls it home."