Senator Fielding has been outspoken in questioning anthropogenic climate change. I wondered who was advising him.

David Evans seems to be not a climatologist but a mathematician who builds climate models.
http://sciencespeak.com/NoEvidence.pdf

Here is a summary, as I understand it. I think there are serious questions here to be answered, but I cannot answer them.

Evidence:

  • Global warming is on trend at around 0.5C per century since the end of the little ice age in 1700.
  • There is a roughly 30 year cycle, with rising temperatures from 1975-2001 and flat to cooler since then.
  • CO2 was 280 ppmv pre-industrial, started rising seriously in about 1945, now 389, still rising on a steady trend.
  • Ice cores show correlation of CO2 and temperatures, with temperature rising 800 years before CO2 (100,000 years).
  • Geologic evidence shows no consistent correlation over earlier periods (many millions of years).
  • There is no geologic evidence of runaway positive feedback despite higher CO2 levels (see later). [Accepted???]
  • Specific predictions made by main models (eg tropical hotspot) have not happened. [Accepted???]
  • Recent direct measurements of climate sensitivity produce an estimate of around 0.5C. [Accepted???]

Known theory (accepted):

  • [Climate sensitivity means how much warming for doubling of CO2 (280 to 570 in 2070)].
  • As GHG without feedback, climate sensitivity is 1.2C. Any deviation from this figure requires feedback because of effect on water vapour. Positive feedback means high figure; negative feedback means lower figure.

Model theory (not accepted):

  • Most assume (without evidence) positive feedback so climate sensitivity is roughly 3.3C (but could be higher or lower).
  • All predictions flow from this assumption. One prediction is the tropical hotspot, but this has not happened (so the model is wrong?).
  • If climate sensitivity is actually 0.5C (negative feedback) then the models produce totally different results.

If you remember just one question, remember this one: climate sensitivity: is the feedback positive or negative?