CO2 Levels Highest in 3.6 Million Years, Yet Temperatures Are Not Following Suit

Federal bureaucrats and their media allies are conducting a targeted public relations campaign promoting reports that atmospheric carbon dioxide concentrations are higher than at any point in the past 3.6 million years. This, they say, is more proof of a climate crisis. However, current temperatures are nowhere near the highest they have been in that same time span. That begs the question, is carbon dioxide really the ‘control knob’ for global temperatures, as climate activists assert? The disconnect between ‘highest-ever’ CO2 emissions and real-world temperatures that are not following suit is powerful evidence that the Earth is far less sensitive to fluctuating carbon dioxide concentrations than alarmists assert.

According to a National Oceanic and Atmospheric Administration (NOAA) press release, “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.”

If climate activists’ theory is correct that carbon dioxide is the primary factor influencing global temperature changes, then current temperatures should be just as warm as they were 3.6 million years ago. Yet they are not.

Also, the NOAA press release forgets to mention that while atmospheric carbon dioxide levels throughout the past 10,000 years were significantly lower than today, global temperatures throughout most of that timespan were significantly higher than today (see page 4, here). Once again, if carbon dioxide is the primary factor influencing global temperatures, why have temperatures been warmer than today throughout most of the time period of human civilization?

Going further back in time, there were many other time periods between 10,000 and 3.6 million years ago when temperatures were significantly higher than today, and yet atmospheric carbon dioxide levels were less than today.

In summary, ‘record’ atmospheric carbon dioxide levels failing to result in record global temperatures shows that climate activists are dramatically overstating the impact of atmospheric carbon dioxide levels on global temperatures – regardless of what government bureaucrats and their media allies assert.

James Taylor
James Taylor
James Taylor is the President of the Heartland Institute. Taylor is also director of Heartland's Arthur B. Robinson Center for Climate and Environmental Policy. Taylor is the former managing editor (2001-2014) of Environment & Climate News, a national monthly publication devoted to sound science and free-market environmentalism.

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  1. Dear Sir:
    The scientific literature is clear.
    1. CO2 can only absorb in certain wavelengths.
    2. Present and past CO2 levels are sufficient to absorb all of earths radiation in those wavelengths. Referred to as being opaque in these wavelengths.

    These facts are well know in scientific circles, but hardly ever mentioned in relation to CO2 and global warming.
    But is means that increasing the amount of CO2 in the air will not absorb any more radiation, thus will not affect global warming.

    Perhaps a physicist could write a piece explaining this.

  2. Don’t count fossil fuels out yet. The atmosphere is CO2 deprived. (418 ppmv compared to 2000 ppmv during the age of dinosaurs) Plants die at 150 ppmv followed soon thereafter by animals(people) CO2 declined to 180 ppmv during the last glacial (20,000 y/a. 2 miles of ice over NY and Chicago back then. CO2 came to within 30 ppmv of mass extinction of plants and animals. It is only 268 ppmv away right now.

    Earth has been in an ice age, defined by ice caps at both poles, for two million years+. During that time, volcanism decreased as Earth’s crust cooled. During that time, the climate cycled between a 100,000-year temperature decline followed by a 20,000-year.temperature increase all the way back to the original temperature. CO2 in the atmosphere declined slowly to the minimum of 180 ppmv. We are in the final stages of the interglacial warm period right now. The next glacial is overdue. Fossil fuels might be preventing its onset.

    So ask yourself, why did the Creator place humans on Earth? Humans have the most powerful animal brain. Humans have a relatively long life span. And, most important, humans have NO fur. Without fur, humans had to learn to control and spread FIRE. Fire creates CO2. The rest of the story is, without fossil fuels, the next mass extinction is not far away. John Kerry, Al Gore, Tom Steyer,, Mike Bloomberg, Joe Biden, AOC and the rest of the phony “Climate Crisis” crowd are the real existential threat to humanity.

    Ron Hughes

    BTW-I have been a Meteorologist/Physical Oceanographer since 1960.


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