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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7 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.

    • 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.

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