There's an interesting discussion of Lewis and Curry at http://www.realclimate.org/index.php/archives/2014/10/climate-response-estimates-from-lewis-curry/, by the way. I suspect a few here would have a problem with them... there was a lot of argument a few days back about the validity of using ocean heat content estimates from the 1970s. One of their dominant parameters is an estimate of OHC in the 1840s! Then there's their choice to ignore the most recent reanalyses (BEST and Cowtan & Way, 2014) which correct for the cool bias in HadCRUT4 by including the previously-excluded arctic. The latter alone would shift their median estimate up by a couple tenths of a degree.
That being said, I for one would be ecstatic if the low end of the range turned out to be correct - but I'm not holding my breath.
