CO2 in Atmosphere Higher than in 2 Million Years, with 2024 the Hottest Year Ever Recorded

Ann Arbor (Informed Comment) – The annual report of the World Meteorological Organization concludes that in 2023, the latest year for which a complete analysis has been carried out, the amount of carbon dioxide (CO₂) in the atmosphere reached its highest level ever recorded —- about 420 parts per million (ppm). That’s 151% higher than it was back in 1750, before large-scale industrial pollution began.

This means there’s now an estimated 3,276 billion tons of CO₂ in the atmosphere.

ChatGPT alleges that “3,276 billion tons (gigatons) of CO₂ traps as much heat as roughly 11 million Hiroshima bombs over 100 years.” We’ve exploded the equivalent of eleven million Hiroshima-sized atomic bombs in our atmosphere by burning all those fossil fuels beginning with the Industrial Revolution (although a lot of it has been burned just in the past 40 years).

Over the course of 2023 alone, CO₂ rose by 2.8 ppm, which is one of the largest jumps in a single year since modern records began in the 1880s. Some of the big increase, though, is because of El Niño, which led to more CO₂ from wildfires and weaker natural systems (like forests) that normally absorb CO₂.

But look, we need to cut the increase in our production of CO2 per year to zero, zilch, nada, not have it go up by 2.8 parts per million per annum! And we need to put in resilience measures to help nature absorb more carbon dioxide. Urban tree cover turns out to do a better job of this than had been realized.

WMO underlines three major takeaways:

“The annually averaged global mean near-surface temperature in 2024 was 1.55 °C ± 0.13 °C above the 1850–1900 average used to represent pre-industrial conditions.

• The year 2024 was the warmest year in the 175-year observational record, clearly surpassing the previous warmest year, 2023 at 1.45 °C ± 0.12 °C above the 1850–1900 average.

• For global mean temperature, each of the past ten years, 2015–2024, were individually the ten warmest years on record.”

They are saying that last year the earth’s surface was 2.8º F. hotter than it had been in the late 19th century before the more dramatic heating caused by the Industrial revolution became starkly apparent. That average temperature means it was the hottest year ever, not only since records began being kept in the late nineteenth century but likely in 2 million years (see below). And they are saying that very single year from 2015 to 2024 ranks among the ten hottest years we’ve ever seen in the 175 years we’ve been keeping track.

The report goes on to specify, alarmingly, that

“CO2 accounts for around 66% of the radiative forcing by all long-lived greenhouse gases since 1750 and about 79% of the increase over the past decade.”

Radiative forcing is a way of measuring the how something changes the balance of energy in the atmosphere, making it hotter. They are saying that carbon dioxide (CO₂) is responsible for about two-thirds of the warming caused by long-lasting greenhouse gases since the year 1750, but that if we just look at the past decade, carbon dioxide is doing most of the heavy lifting all by itself, driving 4/5s of global heating.

Photo by Athena Sandrini: https://www.pexels.com/photo/stop-signboard-on-rocky-field-2994356/

Moreover, they conclude that:

“Current atmospheric concentrations of CO2 [carbon dioxide] are higher than at any time in at least a million years. Concentrations of CH4 [methane] and N2O [nitrous oxide] are higher than at any time in at least 800 000 years.”

The author of the WMO press release on the report got mixed up and said that CO2 is higher than in 800,000 years, but as you see, that is an error. CO2 is higher than at any point in 2 million years.

It matters, because 2 million years ago we were early in the Pleistocene Epoch, when woolly mammoths and saber-toothed tigers roamed the world. The Pleistocene started out hot with the Gelasian Age about 2.5 million years ago, but the planet was already seeing fluctuations during which ice sheets formed at the poles from time to time. From 1.8 million years ago with the onset of the Calabrian Age, it started seeing more frequent and colder periods of glaciation.. In other words, the earth experienced a deep freeze set of Ice Ages that lasted all the way until about 11,700 years ago, when we entered a different cycle in the earth’s orbital patterns. Being forced repeatedly to migrate out of Europe back to the Middle East and even Africa because of the advancing ice sheets would have kept the predecessors of homo sapiens on the run, making it difficult to accumulate and transmit knowledge even after they developed a sophisticated prefrontal cortex about 1.7 million years ago. People likely invented tools but then had to leave them behind and then found them no longer useful for new conditions or just forgot how to make and use them.

The last 10,000 years — the Holocene — had been a kind of Goldilocks story, with the climate just right for the growth of agriculture and civilization. Before the Holocene it was too cold. And before the Calabrian Age it was too hot.

By burning galactic amounts of coal, fossil gas and petroleum, we are rushing headlong back to the early Pleistocene, maybe 2.5 million years before present, when seas were many feet higher and the ice cover was thin and minimal at the poles.

The earth’s orbit over time is sometimes more egg-shaped and sometimes more like a circle, and the earth’s axis tilt also varies, and so does the wobble of its orbit. These repeated changes are called Milankovich Cycles. About 10,000 years ago the northern hemisphere’s tilt toward the sun and the changing orbit exposed it to more sunlight, beginning the melting of the enormous glaciers that had buried Michigan under 3 miles of ice. The glaciers moved as they melted, scooping out depressions and then melting into them, becoming the Great Lakes. So the Pleistocene ended and the milder Holocene began. That’s when human beings managed to begin creating civilization, and it is likely no accident that the new climate of the Holocene, 5 to 10 degrees warmer centigrade than the last three ages of the Pleistocene, was the once in which agriculture and cities developed, allowing for writing, bureaucracy and the emergence of mathematics and science.

But we are destroying that “just right” climate by making it ever hotter by putting more and more carbon dioxide into the atmosphere. Back in 1990 I got myself a nice Seiko Japanese-made watch that had various alarms and other electronic capabilities managed by a small keyboard. In the summer of 1991 I took it with me on a research trip to Pakistan, where it was a 100º F to 113º F and where the humidity skyrocketed when the monsoon rains came. The Seiko watch gradually lost its capabilities, the keyboard became a set of smudges, and the electronic numbers just cycled mindlessly, with some of their edges missing. That’s what heat and humidity do to to sensitive machines. That’s the future of our technology if we are not careful.