There is more carbon dioxide than ever in the atmosphere. That is bad for the climate

The amount of planet-warming carbon dioxide in Earth’s atmosphere has reached a new record as humanity struggles to rein in greenhouse gas emissions from burning fossil fuels.

The new record comes as tens of millions of people struggle with extreme weather in the United States. Much of the western U.S. is experiencing its first major heat wave of the year, bringing temperatures 20 to 30 degrees Fahrenheit hotter than what is normal for June. Temperatures will remain well above 100 degrees in the Southwest.

Such extreme, prolonged heat is directly linked to human-induced climate change, scientists say. All the extra carbon dioxide (CO2) in the atmosphere traps heat and leads to more intense, frequent and persistent heat waves and other extreme weather events such as powerful hurricanes and heavy rain storms.

“This past year we experienced the hottest year on record, the hottest ocean temperatures on record, and a seemingly endless series of heat waves, droughts, floods, wildfires and storms,” said Rick Spinrad, director of the National Oceanic and Atmospheric Administration (NOAA), in a statement. “We must recognize that these are clear signals of the damage carbon dioxide pollution is doing to the climate system and take swift action to reduce fossil fuel use as quickly as possible.”

The concentration of carbon dioxide in the atmosphere is measured in parts per million, and measurements are taken at an observatory in Hawaii. Atmospheric CO2 concentrations peak in May because the gas accumulates more in the winter months, when there are fewer leaves worldwide to soak it up.

In May, the concentration of CO2 in the atmosphere reached almost 427 parts per million, an increase of about 3 parts per million compared to last year’s peak. That’s one of the largest annual jumps ever recorded, scientists say.

The vast majority of planet-warming pollution in the atmosphere comes from people burning fossil fuels such as oil, gas and coal.

The amount of carbon dioxide in the atmosphere has been steadily increasing since scientists began making routine measurements in 1958. At the time, the concentration of CO2 in the atmosphere was 313 parts per million, slightly higher than in the 19th century, when the Industrial Revolution spurred the widespread consumption of fossil fuels.

But in recent years, the growth of CO2 in the atmosphere has accelerated. According to scientists from NOAA and the Scripps Institution of Oceanography at the University of San Diego, CO2 concentrations have risen faster in the first four months of this year than in the first four months of any previous year on record.

Although routine, direct measurements of CO2 in the atmosphere began in the 1950s, scientists are able to use other methods to estimate how much carbon dioxide was in the atmosphere millions of years ago. And there is more carbon dioxide now than there has been in millions of years.

Rising CO2 levels underscore the extent to which humanity’s collective efforts to reduce greenhouse gas emissions and switch to renewable energy sources are falling short of what would be needed to keep global temperatures in check. U.S. greenhouse gas emissions fell slightly last year, but those declines do not put the country on track to meet the Biden administration’s climate goals.