Now there were two papers put out by a Swiss team (you should know who) on consideration of European warming where they argued that natural effects could be ruled out; the first paper argued for
strong water vapour feedback causing the 1980 to 1998 temperature rise and the later paper, using exactly the same data, argued for a reduction in aerosols causing a recovery in temperatures over the same period.
Both of these papers suggested
a strong water vapour feedback.
Not exact matches
Recent observational and modelling evidence thus provides
strong additional support for the combined
water vapour - lapse rate
feedback being around the strength found in AOGCMs.
where it is clear that
water vapour feedback is MUCH
stronger and counteracts the «lapse rate»
feedback.
However, the contributions of
water vapour / lapse rate and surface albedo
feedbacks to sensitivity spread are non-negligible, particularly since their impact is reinforced by the mean model cloud
feedback being positive and quite
strong.
The theory that
water vapour will always provide
strong earming
feedbacks is unlikely.
This
water vapour feedback may be
strong enough to approximately double the increase in the greenhouse effect due to the added CO2 alone.
The study showed that while
water vapour provides the
strongest feedback of the greenhouse gases (GHGs), it is not the cause (forcing) of global climate change.
In AOGCMs, the
water vapour feedback constitutes by far the
strongest feedback, with a multi-model mean and standard deviation for the MMD at PCMDI of 1.80 ± 0.18 W m — 2 °C — 1, followed by the (negative) lapse rate
feedback -LRB--- 0.84 ± 0.26 W m — 2 °C — 1) and the surface albedo
feedback (0.26 ± 0.08 W m — 2 °C — 1).
As regards the role of clouds and
water vapour, Schmidt claims that Lindzen is unique in his belief that they act as a negative
feedback, adding that there are now
strong observational data to the contrary.»
Chris there is every reason to doubt this «general picture of
water feedback» particularly the still yet to proven and in my IMO wrong assumption by the IPCC that
water vapour is a
strong positive
feedback.