Carbon Dioxide Levels Now Higher Than Ever in Human History

Levels have risen more than 50 percent in the last two centuries alone

A coal power plant releasing smoke in front of a body of water
Scientists measured a carbon dioxide concentration of 420.99 parts per million, an increase of 1.8 ppm over 2021.  Jacek Kadaj via Getty Images

The amount of carbon dioxide (CO2) in the atmosphere has hit a historic high, shooting up to levels not seen for 4 million years, the National Oceanic and Atmospheric Administration (NOAA) announced in a statement last week. 

Scientists measured a concentration of 420.99 parts per million (ppm) at NOAA’s mountaintop observatory in Hawaii, an increase of 1.8 ppm since 2021, per the administration. 

“Watching these incremental but persistent increases in CO2 year-to-year is much like watching a train barrel down the track towards you in slow motion. It’s terrifying,” University of Wisconsin-Madison climate scientist Andrea Dutton tells Seth Borenstein of the Associated Press. “If we stay on the track with a plan to jump out of the way at the last minute, we may die of heat stroke out on the tracks before it even gets to us.”

Around four million years ago, during the Pliocene Climatic Optimum, carbon dioxide levels were similar—close to or above 400 ppm, per NOAA. The earth was seven degrees hotter, ice caps at both the North and South Poles nearly completely melted and sea levels were 16 to 82 feet higher, high enough to submerge many major cities, the administration says. Paleoclimatologists can learn about past climates by looking at tree rings, ice cores, and mineral and element compositions in sediment core samples as well analyzing plant and animal remains. Particularly useful are forams and diatoms, shelled creatures that frequently record climate conditions in the compositions of their shells.

“Carbon dioxide is at levels our species has never experienced before,” Pieter Tans, senior scientist with NOAA’s Global Monitoring Laboratory says in the statement. “We have known about this for half a century, and have failed to do anything meaningful about it. What’s it going to take for us to wake up?” 

From analysis of gas composition in ice core samples, scientists can tell that for almost 6,000 years of human history before the Industrial Revolution of the 18th and 19th centuries, carbon dioxide levels stayed consistently around 280 ppm. The advent of mass industry during the Industrial Revolution spurred emissions on, particularly from burning fossil fuels, especially coal and oil.

But carbon emissions from human activities have increased rapidly. Last year, 36.3 billion tons of global energy-related carbon dioxide were released, the highest ever recorded, and carbon emissions from the use of coal reached an all-time high of 15.3 billion tons. 

According to the EPA, the three biggest sources of carbon emission worldwide are the transportation industry (27% of emissions in 2020), the production of electricity from all sources (25%, with fossil fuels making up 60% of this share), and general industrial activity in general, like the production of raw industrial materials (24%).

Now global temperatures are about 2 degrees Fahrenheit higher than before the Industrial Revolution, writes Henry Fountain for the New York Times

Earlier this year, an Intergovernmental Panel on Climate Change (IPCC) report warned that rapid and deep cuts to greenhouse gas emissions are needed to hit the goal of keeping global warming at only 1.5 degrees Celsius (or about 2.7 degrees Fahrenheit). This was another in a series of government and non-profit reports on the devastating effects of human-induced climate change on various facets of the planet, including Earth’s water supply and biodiversity loss.

Overall human carbon dioxide? emissions must be reduced by 43 percent by 2030 and 84 percent by 2050.  By 2050, global coal use must drop by 95 percent compared to 2019.

The effects of human emissions on climate have been discussed by international organizations for decades—the first UN meeting on climate took place all the way back in 1972, yet unified action has been difficult to come by. 

“It’s depressing that we’ve lacked the collective will power to slow the relentless rise in CO2,” says Ralph Keeling, a geochemist who runs CO2 measurements for the Scripps Institution of Oceanography in Hawaii, in a statement. “Fossil-fuel use may no longer be accelerating, but we are still racing at top speed towards a global catastrophe.” 

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