Carbon dioxide at levels not seen for 3.6 million years despite economic slowdown from pandemic

The reason I told my readers to "stay tuned for a climate update tomorrow" was that my wife checked the weather at NOAA and saw the following headline Despite pandemic shutdowns, carbon dioxide and methane surged in 2020. CBS News summarized and commented on that in Greenhouse gas levels surged in 2020, NOAA says.

A new report from the NOAA finds that despite global shutdowns, greenhouse gas levels in 2020 surged. In fact, levels of carbon dioxide are at the highest they've been in 3.6 million years. CBS News meteorologist and climate specialist Jeff Berardelli joins CBSN to explain.

Jeff Berardelli and anchor Lana Zak concentrated more on the rate of increasing greenhouse gas concentrations and temperatures, the consequences of the higher temperatures, and what humans can do to keep temperatures from rising more than two degrees Celsius above pre-industrial levels than they did on the effects of the pandemic-driven recession or the implications of the subtitle of the report, "Carbon dioxide levels are now higher than at anytime in the past 3.6 million years." Follow over the jump for the first half of the NOAA press release with my commentary on those two subjects.

Increases in the monthly average carbon dioxide measurements at NOAA's Mauna Loa Observatory are depicted in these graphs. Credit: NOAA Global Monitoring Laboratory.

I begin by repeating the information in the headline.

Levels of the two most important anthropogenic greenhouse gases, carbon dioxide and methane, continued their unrelenting rise in 2020 despite the economic slowdown caused by the coronavirus pandemic response, NOAA announced today.

The global surface average for carbon dioxide (CO₂), calculated from measurements collected at NOAA’s remote sampling locations, was 412.5 parts per million (ppm) in 2020, rising by 2.6 ppm during the year. The global rate of increase was the fifth-highest in NOAA’s 63-year record, following 1987, 1998, 2015 and 2016. The annual mean at NOAA's Mauna Loa Observatory in Hawaii was 414.4 ppm during 2020.

That's part of the bad news.

The economic recession was estimated to have reduced carbon emissions by about 7 percent during 2020.I can't tell if this is the good news or the bad news.Without the economic slowdown, the 2020 increase would have been the highest on record, according to Pieter Tans, senior scientist at NOAA’s Global Monitoring Laboratory.

That's what passes for good news in this report. Still, it's not surprising, as Dr. Katherine Hayhoe predicted in the videos I embedded in Coronavirus response reducing air pollution updates climate change and the environment for the ninth year of Crazy Eddie's Motie News, I repeated in The effect of the pandemic on the environment for World Environment Day, and Greta Thunberg reiterated in Stephen Colbert interviews Greta Thunberg about climate change and coronavirus. The reduction in emissions was not enough to reduce greenhouse gas levels, just make them rise more gently, and it's only temporary. The slowdown will end when the pandemic does. I just hope the bicycle boom and Zoom meetings continue enough to have a positive effect on the environment.

Since 2000, the global CO2 average has grown by 43.5 ppm, an increase of 12 percent.

Again, not news, but still scary.

Now onto the part of the press release that interested me as a paleontologist.

The atmospheric burden of CO₂ is now comparable to where it was during the Mid-Pliocene Warm Period around 3.6 million years ago, when concentrations of carbon dioxide ranged from about 380 to 450 parts per million. During that time sea level was about 78 feet higher than today, the average temperature was 7 degrees Fahrenheit higher than in pre-industrial times, and studies indicate large forests occupied areas of the Arctic that are now tundra.

I mentioned the 3.6 million years ago comparison in More news about the 400 ppm world when I quoted Erin Wayman of Science News eight years ago.

Pliocene epoch featured greenhouse gas levels similar to today's but with higher average temperatures

The Arctic wasn’t always frozen tundra. About 3.6 million years ago, the far north was blanketed in boreal forests, and summers were 8 degrees Celsius warmer than they are today, geologists report May 9 in Science.

Researchers pieced together that picture from sediments buried beneath Lake El’gygytgyn (pronounced EL-gih-git-gin), about 100 kilometers north of the Arctic Circle in northeastern Russia (SN: 11/20/10, p. 13). The sediments preserve the most complete history of Arctic climate on land over the last 3.6 million years.

“It’s an unprecedented record,” says study coauthor Julie Brigham-Grette, a geologist at the University of Massachusetts Amherst. “It gives us a way of envisioning what the future may hold.”

When I searched Wikipedia for the name of the time period 3.6 million years ago, I found that it marked the base of the Piacenzian: "The Piacenzian is in the international geologic time scale the upper stage or latest age of the Pliocene. It spans the time between 3.6 ± 0.005 Ma and 2.588 ± 0.005 Ma (million years ago)." I also found another passage decribing why scientists are studying its climate as an possible predictor of what is in store for our future.

The Piacenzian was the last age before the Quaternary glaciations started to take hold in the Northern hemisphere. The ice sheet of Antarctica was also less prominent than today and sea levels were approximately twenty meters higher than the present. The global mean temperature was 2–3 °C warmer than the pre-industrial temperature. During the Mid-Piacenzian Warm Period the concentration of carbon dioxide peaked at approximately 389 ppm (in the range 381–427 ppm with 95% confidence), thus similar to the concentration during the 2010s. The Piacenzian can therefore be used as an analogue to the future climate and sea level to expect if the carbon dioxide concentration stabilizes at this level. In particular, the KM5c interglacial during the Mid-Piacenzian Warm Period occurred during an orbital configuration close to the current situation, with similar geographical distribution of solar insolation.

That was so long ago, terror birds and hyenas roamed North America. As I wrote eight years ago, the Earth was a very different place 3.6 million years ago. Also, as I repeated most recently in 'California wildfires illustrate the consequences of climate change' — PBS NewsHour, welcome to the 400 ppm world.

Enough DOOM. Stay tuned for more on the Oscar nominees tomorrow, the Sunday entertainment feature.