Greenhouse gas on Earth is back to Pliocene levels

Things on Earth were pretty different 4.3 million years ago during the mid-Pliocene epoch. However, one thing from that time is comparable to modern life – the atmosphere.

According to a recent report from the National Oceanic and Atmospheric Administration , the amount of carbon dioxide in the atmosphere today “is comparable to where it was around 4.3 million years ago during the mid- Pliocene epoch , when sea level was about 75 feet higher than today, the average temperature was 7 degrees Fahrenheit higher than in pre-industrial times, and large forests occupied areas of the Arctic that are now tundra.”

While the Pliocene was actually an era of global cooling, per the University of California Museum of Paleontology , the Pliocene is thought to have had a much warmer climate than we do today. Its warmest phase was the mid-Pliocene.

Surface concentration of carbon dioxide inched up every month of 2023, an increase of 2.8 parts per million over the previous year. That year also marked the 12th in a row with an increase over 2 parts per million, “extending the highest sustained rate of carbon dioxide increases during the 65-year monitoring record,” per the NOAA.

“The 2023 increase is the third-largest in the past decade, likely a result of an ongoing increase of fossil fuel CO ₂ emissions, coupled with increased fire emissions possibly as a result of the transition from La Nina to El Nino,” said Xin Lan, a scientist who leads an effort to synthesize data from the NOAA Global Greenhouse Gas Reference Network for tracking global greenhouse gas trends

Carbon dioxide – a gas that often enters the air through burning fossil fuels – is one of the major greenhouse gases known to trap heat in the Earth’s atmosphere and contribute to warming global temperatures, according to the U.S. Environmental Protection Agency .

Other greenhouse gasses are methane, nitrous oxide and fluorinated gases. California is the largest contributor to emissions of one particular greenhouse gas, the pesticide sulfuryl fluoride, according to a study published this month .

Of all greenhouse gases, carbon dioxide remains the biggest contributor to climate change. From the 1960s to last year, human-caused carbon dioxide emissions increased from 10.9 billion tons per year to 36.8 billion tons per year – a new record.

“Levels of the three most important human-caused greenhouse gases – carbon dioxide, methane and nitrous oxide – continued their steady climb during 2023, according to NOAA scientists,” the administration said this month. This year’s jump may not have been as high as it was in previous years, but it still added to consistently increasing emissions.

Around half of the carbon dioxide emissions that come from fossil fuels have been absorbed at the Earth’s surface, said the NOAA. These are spread roughly equally across oceans and land ecosystems.

When carbon dioxide is absorbed by oceans, it makes them more acidic. This process is causing a “fundamental change in the chemistry of the ocean, with impacts to marine life and the people who depend on them,” the NOAA explained.

While carbon dioxide levels rise, researchers are looking for ways to mitigate the problem.

Richard Conant, a soil biogeochemist and head of Colorado State University’s Department of Ecosystem Science and Sustainability is working on something called biotransformative carbon dioxide removal. His research team is looking to find decomposition-resistant compounds and encourage plants to make them, thus creating crops that would consume carbon dioxide from the atmosphere.

“We think biotransformative CDR has the potential to produce verifiable, dependable, durable carbon removal at lower cost, and it could be scaled quickly,” Conant said . “We think it’s a potentially transformative solution.”