

By Juan Cole | (Informed Comment) | – –

The Mauna Loa Observatory in Hawaii has reported that in April, for the first time in human history the level of carbon dioxide in the atmosphere has exceeded 410 parts per million (ppm). Carbon dioxide (CO2) is a powerful greenhouse gas that prevents the sun’s heat from radiating back out into space once it strikes the surface. It is because Venus’s atmosphere is mainly CO2 that the planet is a torrid hell-hole where metals melt on the surface.

New scientific estimates are that the last time there was this much carbon dioxide in the earth’s atmosphere may have been the Pliocene, some 4.5 million years ago. Some earlier estimates suggested that it had been 24 million years since we had this much CO2. In past eras, carbon dioxide levels tended to go up mainly because of volcanic eruptions. The CO2 gradually gets scrubbed back out of the atmosphere by going into the ocean or by binding with igneous rock, over hundreds of thousands or millions of years. In the meantime, more CO2 means more heat.

Although the Pliocene was cooler than the preceding era, the middle Pliocene was still substantially hotter than the earth is today.

There were dire wolves and camelops and giant armadillos.

Sea levels 4.5 million years ago were as much as 131 feet feet [40 meters] higher than today.

Here are the coastal communities in the US at risk just from a four feet ocean level rise:

h/t Climate Central

It will be much more.

As the video below makes clear, our climate models are likely overly conservative. 410 ppm of carbon dioxide had a much bigger effect on the Pliocene than we would have thought, according to new analyses of ocean temperatures. It got hot, and ocean temperatures were unaccountably torrid. That dried out East Africa and may have affected the evolution of early hominids there.


Related video:

UCLTV: “Climate models questioned by Pliocene ocean temperatures”

9 Responses

  1. If any historians survive the mess that might hit us any year now, in the worst projections, will they say that American-sponsored petroleum-powered civilization suffocated itself?

    That’s the very worst projection, that we’ve already gone too far, the climate changes & the human changes of the next couple of decades should tell. I do encourage looking at, and working towards, the most optimistic projections also.

  2. I dont understand what we are doing with this planet. I mean this is our home we suppose to take care of this. Now I belong to a country where winter where really cold and we also used to have snow fall but for last 10 years there is no snow fall and when the winter season comes you only need a blanket for 10 days and after that the winter is like gone I dont know where will it end but I dont think so we will be having any winter after 10 years.

  3. It is good that the graphic points out the energy facilities that will be under water. How many are nuclear/ This is an issue no one mentions. It takes 20-30 years to decommission a
    nuclear plant. They are usually located close to water for the cooling. Often the waste is stored on site, since there is
    no agreed on alternative (no one wants it transported on trains by or to their state). Rationally we should- worldwide-
    close down all nuclear plants located near the sea immediately and begin the decommissioning. Practically,
    this will be kicked down the road until the waters rise, and we’ll essentially have tens of Fukushimas. Oh, and Fukushima itself will flood again…

    Regarding the non-nuclear facilites, like refineries? It would be good to know what the situation is….

  4. If we stop putting carbon into the atmosphere today and freeze the CO2 level at 400 ppm, it will still take several thousand years for the earth’s climate to reach equilibrium. There’s a lot of warming ahead.

  5. Actually, dire wolves, Camelops, and Glyptodon (extinct armadillo) are Pleistocene fauna, when it was generally cooler. (Camelops appear in the late Pliocene but are mostly Pleistocene.)

  6. During the mid-Pliocene with the same carbon dioxide levels as now the sea stand was about 25 meters higher than now and the global temperature was 2+ °C higher than now. So if carbon dioxide levels remain at the same level as now, and then, at equilibrium those same conditions will obtain.

    Source is the Wikipedia page on Pliocene climate.

  7. According to IPCC (the most authoritative source for climate data), in the 20th century, global sea levels rose by approx 20-30 cm. IPCC expects expect global sea levels to rise by another 30-60 cm during the 21st century. The question is whether US power plants and US cities can adapt to this challenge over this timeframe.

  8. I recently saw a map of where the coastlines would be if ALL the world’s ice melted — the ultimate worst-case scenario. As you would expect, Bangladesh is gone, the Bahamas, Cuba becomes two islands, etc. But it appeared the two biggest land losses by far would be (1) eastern China north of Shanghai and extending inland clear to Beijing, an immense area that must be home to 300-400 million people, and (2) the southeastern United States. Florida disappears entirely, of course, but in fact the entire Atlantic and Gulf coastal plains stretching from the Carolinas to Texas would be submerged right up to the Appalachian foothills. The mouth of the Mississippi River would be about Memphis, Tenn.

    So at least there will be some justice in that the two biggest contributors to the catastrophe — the United States and China — will also be the two biggest losers, at least in land mass. And in America, the land mass lost will be precisely where the largest concentration of climate change deniers resides.

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