Carl Sagan on Global Warming

September 5, 2011

Although I have posted video of Carl Sagan and Steven Hawking talking about global warming – I had not seen this 1990 update to the Cosmos series, where Sagan warns of climate change.

 

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14 Responses to “Carl Sagan on Global Warming”

  1. otter17 Says:

    I was too young to remember the Cosmos series, but I hear Sagan was quite the science communicator. I ought to check out parts of it on Youtube sometime.

  2. danolner Says:

    Any idea what the current thinking is on the Venutian scenario? Is it within the bounds of any robust business-as-usual models, up to or past 2100?

    • greenman3610 Says:

      major consensus would be that’s impossible. I think James Hansen does not rule it out under a “burn it all” regime.
      Nevertheless, there are many degrees of pretty hellish changes a long ways before you get to Venus conditions.

    • otter17 Says:

      Quote from “Storms of My Grandchildren” end of chapter 10, The Venus Syndrome.

      >>
      “After the ice is gone, would Earth proceed to the Venus syndrome, a runaway greenhouse effect that would destroy all life on the planet, perhaps permanently? While that is difficult to say based on present information, I’ve come to conclude that if we burn all reserves of oil, gas, and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty.”

    • rpauli Says:

      In one sense, the question is moot – since all life will be long gone before a time when the oceans boil off and we become like Venus

      A more important scenario, and quite plausible is a 6 degrees warming as great as that of the Permian Extinction. Such an apocalypse has happened, and could happen again.

      The end-Permian mass extinction of 251 million years ago was associated with six degrees of warming, and wiped out 90% of life on Earth.
      In such a time, huge firestorms sweep the planet as methane hydrate fireballs ignite. Seas turn anoxic and release poisonous hydrogen sulphide.
      “Under a Green Sky” by paleoclimatologist Dr. Peter Ward – said that may have happened 7 times in earth’s history,

      National Geographic described each of the degrees in a documentary. Mark Lynas has a great book “Six Degrees – Our Future on a Hotter Planet”

      Right now we have experienced almost a full degree – and we are on track for an inevitable 2 degrees of warming.

      That is why the present time is so crucial. Whatever carbon emissions we add will increase heat decades from now.

      Humans WILL STOP emitting CO2 – it is just whether it will be willingly or by mass extinction.

      http://localsteps.org/6degreemap.html

    • otter17 Says:

      I second the “6 Degrees” recommendation. In particular, the book is filled with a lot of good content, all cited from the peer review literature.

  3. rpauli Says:

    Sagan reflected scientific conclusions of 1990 – the laws of science have not changed in the last 20 years. The same conclusions are being constantly rediscovered – The laws of CO2 heating the atmosphere remains.

    The real problem is human denial. Enhanced by organized opinion makers and PR campaigns. Even those who get the science of AGW refuse to change.

    The problem is not with the climate conditions – they are just there – the real problem is with human psychology and our refusal to change.


  4. Sagan also made statements about global cooing.

    ” . . . But we have also been perturbing the climate in the opposite sense. For hundreds of thousands of years human beings have been burning and cutting down forests and encouraging domestic animals to graze on and destroy grasslands. Slash-and-burn agriculture, industrial tropical deforestation and overgrazing are rampant today. But forests are darker than grasslands, and grasslands are darker than deserts. As a consequence, the amount of sunlight that is absorbed by the ground has been declining, and by changes in the land use we are lowering the surface temperature of our planet. Might this cooling increase the size of the polar ice cap, which, because it is bright, will reflect still more sunlight from the Earth, further cooling the planet, driving a runaway albedo2 effect?”

    For some reason, we don’t ever read about that. Can you say “cherry picking?”

    • greenman3610 Says:

      Your quote is from the original Cosmos book, written in the late 70s, early 80s. The video above, and Sagan’s subsequent writings, indicate his better informed view of climate, with the benefit of a decade more data. Your inability to make this distinction reflects poorly on your reasoning abilities.

      • dumboldguy Says:

        He has enough “reasoning ability” to cherry pick horsepucky himself, though. What really calls his “reasoning ability” into serious question is his cherry-picking of a 30+ year old quote that has obviously been steamrolled by events since—-like the melting of the Arctic sea ice and the darkening of the Greenland ice “cap”.

        “RUNAWAY albedo COOLING effect”? Lord love a duck, but that’s the first time anyone has laid that one on us. Where has Jeffery been over the past couple of decades?


    • Talk about cherry picking!
      how about including the paragraph before this one.


    • Talk about cherry picking!
      What about the sentence or paragraph before?

      “The principal energy sources of our present industrial civilization are the so- called fossil fuels. We burn wood and oil, coal and natural gas, and, in the process, release waste gases, principally CO 2 , into the air. Consequently, the carbon dioxide content of the Earth’s atmosphere is increasing dramatically. The possibility of a runaway greenhouse effect suggests that we have to be careful: Even a one- or two- degree rise in the global temperature can have catastrophic consequences. In the burning of coal and oil and gasoline, we are also putting sulfuric acid into the atmosphere. Like Venus, our stratosphere even now has a substantial mist of tiny sulfuric acid droplets. Our major cities are polluted with noxious molecules. We do not understand the long- term effects of our course of action. But we have also been perturbing the climate in the opposite……”


    • Talk about cherry picking!
      What was the part before your quote.

      “The principal energy sources of our present industrial civilization are the so- called fossil fuels. We burn wood and oil, coal and natural gas, and, in the process, release waste gases, principally CO 2 , into the air. Consequently, the carbon dioxide content of the Earth’s atmosphere is increasing dramatically. The possibility of a runaway greenhouse effect suggests that we have to be careful: Even a one- or two- degree rise in the global temperature can have catastrophic consequences. In the burning of coal and oil and gasoline, we are also putting sulfuric acid into the atmosphere. Like Venus, our stratosphere even now has a substantial mist of tiny sulfuric acid droplets. Our major cities are polluted with noxious molecules. We do not understand the long- term effects of our course of action. But we have also been perturbing the climate in the opposite…”


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