WUWT has posted with details of a leak by Alec Rawls of the AR5 WG1 draft suggesting some kind of solar effect is acknowledged.
Link to WUWT on AR5 draft entitled “IPCC AR5 draft leaked, contains game-changing admission of enhanced solar forcing”
The IPCC mentioning the possibility of a GCR link to clouds is important here. Prof Nir Shaviv in his JGR paper on Using the Oceans as a Calorimeter found a large amplification by empirical study. Cloud change is likely to be proportional to solar change because otherwise our solar planetary model wouldn’t successfully hindcast a good match to the paleo reconstructions.
David L. Hagen says:
Cloud change – another major “omitted variable”.
Re section: 188.8.131.52 Clouds
The declining cloud cover reported Eastman & Warren 2012 is an equally major “omitted variable”.
My proposed summary of Eastman & Warren is as follows:
“The global average cloud cover declined about 1.56% over 39 years (1979 to 2009) or ~0.4%/decade, primarily in middle latitudes at middle and high levels (Eastman & Waren, 2012). Declining clouds appear to be a major contributor to the observed global warming. A 1 percentage point decrease in albedo (30% to 29%) would increase the black-body radiative equilibrium temperature about 1°C, about equal to a doubling of atmospheric CO2. e.g. by a 1.5% reduction in clouds since they form up to 2/3rds of global albedo (IPCC report AR4 1.5.2 p.114). The challenge now is distinguish what portion of rising CO2 reduced clouds and what portion of natural reduction in clouds raised ocean temperatures increasing CO2.”
See: “Ryan Eastman, Stephen G. Warren, A 39-Year Survey of Cloud Changes from Land Stations Worldwide 1971-2009: Long-Term Trends, Relation to Aerosols, and Expansion of the Tropical Belt Journal of Climate 2012 ; e-View doi: http://dx.doi.org/10.1175/JCLI-D-12-00280.1”
For discussion, graphs see Some confirmation of Spencer’s cloud hypothesis – it is getting less cloudy and warmer at the same time WUWT Aug 20, 2012
In his Solar Accumulation Theory, David Stockwell provides further evidence for major solar causation for warming.
The solar amplifying mechanism together with the major trend of declining cloud cover create influences that could entirely explain ALL the warming. This raises the major causation puzzle (aka “chicken and egg”) of which parameters are the cause and which the consequence.
Ben Santer et al. 2012 Identifying human influences on atmospheric temperature
On average, the models analyzed … overestimate the warming of the troposphere. Although the precise causes of such differences are unclear…
The multimodel average tropospheric temperature trends are outside the 5–95 percentile range of RSS results at most latitudes.
Where do the models fail?
1. Significantly warmer than reality (95% CI) in the lower troposphere at all latitudes, except for the arctic.
2. Significantly warmer than reality (95% CI) in the mid-troposphere at all latitudes, except for the possible polar regions.
3. Significant warmer that reality (95% CI) in the lower stratosphere at all latitudes, except possibly polar regions.
Answer: Everywhere except for polar regions where uncertainty is greater.
Attributing most of the global warming to fossil CO2 appears increasingly to be an “argument from ignorance” with little statistically justifiable basis once these issues are identified and quantified. Consequently “Minor anthropogenic warming” will likely be the major contender – when we can actually quantify (“about”) how much of < 50% is due to anthropogenic CO2!