Couldn't positive feedbacks account for late 20th century warming?

As most of you probably know, the rise in solar irradience correlates very nicely with the warming we had from 1900 to 1940, and indeed many scientists feel it was responsible for the vast majority of the warming during this time:

So how is it not possible that this increase in temperatures indirectly spawned positive feedbacks (water vapor, ice albedo, oceanic CO2 release, PDO/ENSO...etc) which accounted for most of the warming of 1970-today?


Thanks Capn T...that report is about 'sunspot cycle length' though, which is different from total solar irradiance.

3 Answers

  • 1 decade ago
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    Because there is no physical mechanism by which an increase in total solar irradiance (TSI) causes feedbacks 70 years later.

    Just consider the fact that TSI stopped increasing in about 1945. There was a long pause in the increasing global temperature from 1940-1975, then the planet began warming rapidly.

    There is simply no physical mechanism to explain why after TSI stopped, it didn't cause any increase in global temperature for 30 years, then suddenly it caused a rapid increase for several decades starting in 1975.

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  • 4 years ago

    I think perhaps we should address how the cooling data was taken first before we make any assumptions.... From 1942 to August 1945 about 80 per cent of temperature records at sea were by US ships, which typically sampled water piped into hulls that can be heated by warmth of engines. From late 1945-49, about half of a smaller batch of measurements were made by British ships, which typically scooped up water in buckets. Water in buckets often cools before thermometers can be put in, especially in winter. This can seriously skew results and averages,ergo perhaps there was neither a cooling or a warming.

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  • Anonymous
    1 decade ago

    Hopefully this peer-reviewed publishing will help answer your question:

    The paper was referenced in New Scientist magazine

    Edit: Give this one a try:

    For full disclosure, David Douglass, one author of the above study, received payments form Exxon. Take that for what it's worth.

    Source(s): On the author, Stephen Schneider
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