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  1. #1
    Roger Steer's Avatar
    Roger Steer Guest

    Default Global warming v. Solar warming

    At the risk of waking up the trolls - Sorry!

    There has been a lot of talk lately about the rise in earth temperature
    being caused by a secular increase in solar output rather than the
    greenhouse effect of various pollutants.

    Surely there is an easy way of getting some objective evidence on this?
    Mars has been closely observed for many years. If this is a solar
    effect, the polar caps, as seen at different apparitions, but at
    comparable distances from the sun, should show a variation over time.
    If not, then the greenhouse gasses are to blame.

    But that might settle the argument, so perhaps it's a bad idea.


  2. #2
    Martin Brown's Avatar
    Martin Brown Guest

    Default Global warming v. Solar warming

    Roger Steer wrote:

    The sun is gradually getting brighter. There is good evidence for this
    and it is predicted by all the models of stellar evolution and confirmed
    by direct measurements of solar flux by satellites since the 1970's.

    Not even GW sceptic scientists can balance the Earth's energy budget
    post 1970 without taking into account the contribution of anthropogenic
    greenhouse gas forcing. They may say "there is still reasonable doubt"
    but the scientific evidence for GW is unambiguous.

    This exploits a common logical fallacy. We know the sun is brightening
    so we should expect to see Mars warming slightly and indeed we do. Its
    atmospheric pressure of CO2 is rather sensitive to solar flux. But that
    tells us nothing useful about greenhouse gas forcing on Earth.

    Both solar and atmospheric composition effects are present and act to
    make the Earth warmer. Finding evidence of one does not exclude the
    other. There are many other competing effects like cloud type and
    coverage too.

    A simpler example exploiting the same cause/effect fallacy.

    I walk conspicuously into a shop wearing a very obvious ID card that
    sets off the stock control alarm at the door. Apologise profusely to the
    guard and go in to shop. I can then steal whatever I want and on leaving
    the alarm will go off again. Put shopping down outside the shop and wait
    looking really embarrassed. Then I demonstrate to the security guard
    again that my ID badge sets off their alarm. Because he remembers I set
    off the alarm going in he assumes (incorrectly) that is the only cause
    on the way out.

    Security guards should be trained not to fall for this trick, but until
    they are shown it most are easily fooled. It is necessary to show that
    none of the other shopping bags trigger the alarm to prove innocence.

    I am not surprised that the anti-GW lobby are using this old chestnut.

    Martin Brown



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