Hansen 1981 : -55C Temperatures On Mars Prove CO2 Warming

Published: August 22, 1981

In their analysis, the scientists seek to respond to an outspoken skeptic regarding the carbon dioxide threat, Dr. Sherwood B. Idso, a climate specialist with the Federal Department of Agriculture in Phoenix. Last March he circulated an analysis saying that a doubling or tripling of atmospheric carbon dioxide would have little effect except to increase global agricultural productivity by 20 to 50 percent.

Dr. Hansen and his colleagues cite the observed surface temperatures of Mars and, particularly, Venus as support for their predicted greenhouse effect. The surface of Venus, with an atmosphere formed largely of carbon dioxide, is at about 900 degrees Fahrenheit.


Both Mars and Venus have 95% CO2 atmospheres. Venus is hot because of the high atmospheric pressure, not because of the CO2.


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18 Responses to Hansen 1981 : -55C Temperatures On Mars Prove CO2 Warming

  1. Ernest Bush says:

    Does Dr. Idso still have a job?

  2. Meanwhile Mars’ atmospheric pressure is less than 1% of Earth’s. Average surface temperatures are -60s.

  3. Steve Case says:

    CO2 is 95% on Venus and it’s hot enough to melt lead, 95% on Mars and it’s so cold it snows dry ice, and 0.04% on Earth where we are told it’s the primary driver of temperature.

  4. Venus also happens to be closer to the Sun than Mars. That makes a little bit of difference.

    • That actually has nothing to do with it. A thick layer of clouds in Venus upper atmosphere reflects most of the sunlight back into space, giving Venus its very bright appearance.

      • squid2112 says:

        Very little short wave radiation from the sun makes it to the Venusian surface, therefore, the “green house effect”, as it is described by the Global Warming Nazis, through back radiation, is quite simply impossible. As Steven points out, Venus is indeed one of the brightest planets in our solar system, often visible to the naked eye, even during daylight hours here on earth.

        Venus is the perfect example of how there is no such thing as a “green house effect” … period.

    • Robertv says:

      Kilimanjaro is also closer to the Sun .

  5. Password protected says:

    Density of the atmosphere seems to be important in how much heat it can hold.
    The increase in CO2 in earths atmosphere is at trace levels. Minimal change in density.

  6. Ben Vorlich says:

    How many million (perhaps billion) years has the CO2 on Mars had to warm up the surface temperature.?

  7. Password protected says:

    It’s heat that determines temp for a given density. A given amount of heat will create different temps for different densities, water/air for example.

  8. nevmanser says:

    Venus has a mostly CO2 atmosphere of incredible density and pressure. Radar has been used to ‘examine’ its surface contour wise but there is no idea of how much or little geology is contributing to atmospheric temperature. For all we know immense amounts of vulcanism (excuse the pun) and lava flows may be happening or had happened to raise temperatures on Venus. Hansen may have been on the right spot at the right time for NASA to discover Venus’ high CO2 levels but methinks he has made too much capital (again, excuse the pun) from that discovery which wasn’t all because of his efforts alone.

  9. In addition, base of troposphere on Uranus is 320K [per Wikipedia], considerably hotter than Earth, despite being nearly 30 times further from the Sun. The only explanation is pressure, not greenhouse gases.

    • Robert Austin says:

      Yes, it is interesting that the base of the Uranian troposphere, the nominal surface, is deemed to be at 100 bar which is the pretty much same as the surface pressure of Venus. And again we see a dense atmosphere, not greenhouse gases, responsible for the relatively high 320K temperature at this altitude.

  10. Also, even though Earth & Venus have about the same mass/gravity, the atmospheric mass Venus is 2 orders of magnitude higher than Earth:

    Venus atmospheric mass: 4.8 x 10^20, surface pressure: 92 bars
    Earth atmospheric mass: 5.2 x 10^18, surface pressure: 1 bar

    The dry adiabatic lapse rate on Venus is 10.47K/km, almost the same as the dry adiabatic lapse rate on Earth 9.8K/km, despite very different atmospheric composition.

    10.47K/km * 71 km mean emission height = 740K observed surface temp

  11. Paul Apollonio says:

    These comment boards are full of global warming nay-sayers. How many I wonder on the oil company payroll. Why don’t you guys publish peer reviewed science to make your case? I guess it’s the peer review process and the science part.

    As our carbon climbs, the temps follow. Methane is of course, a much bigger threat than CO2. We still have the opportunity to save the planet from the course of ecological suicide we are now headed down, yet the deniers are content to pay the mortgage and betray the planet. It’s only proof some people have no conscience.

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