Another interesting entry on the often-provoking RP Sr site. This time a guest post by McNider, who I don’t know. He indulges in some giveaway ranting: Climate change alarmists have used the global surface temperature record as evidence of man’s impact on climate being “real” yet, as discussed below, most of the warming in this record is at night and probably has little to do with the accumulation of heat in the atmosphere which is foolish, unless you want to dismiss the IPCC as alarmists, which leaves you amongst the wild-eyed Lubos fringe. And requires you to believe some strange things about the SST record.
But leaving that regrettable stuff aside, there is some interesting substance, about the effects of radiative forcing on boundary layer stability and the diurnal temperature range (DTR). I don’t vouch for the statments about DTR in general there; for the official view there is stuff about DTR if you care to read it from IPCC chapter 3 (scroll down to p251 and above).
So their thesis is that there is a regime in which increasing radiative forcing will warm the surface somewhat; this in turns reduced the atmospheric stability somewhat; which allows more vertical mixing and pulls down warmer air for above, leading to more surface warming. This seems quite plausible and quite interesting. Their comments on this being a process missing (or poorly represented) in GCMs is also quite possibly correct, since GCMs tend to use adjusted stability functions (which are nominally to represent inhomogeneous terrain, but are probably in there because the std theoretical functions are thought to lead to “runaway stability” under certain conditions (the idea being that on cold nights the sfc cools by radiation, cooling the air just above; this increases the stability and since heat transfer reduces with stability, the heat flow to the sfc reduces, leading to further cooling, until heat transfer shuts off entirely and the sfc sits there cooling radiatively. Only my experiments with HadCM3 says this doesn’t actually happen. But thats another story)). Are we out of the brackets yet?
But the bit they seem to care most about, and which I think is wrong, is about heat accumulation: The essay ends with a plea to discard nighttime temperatures as a means to track heat accumulation in the atmosphere from greenhouse gases or other positive radiative forcing. Since no-one (except them) are proposing to use heat accumulation as a measure of warming, who cares? What people use is temperature, which is the thing people care about. If this is a feedback that increases surface warming then… thats what it is. But it isn’t a problem with GW in general. And saying the minimum temperatures measured in the nocturnal boundary layer represent only a very shallow layer of the atmosphere which is usually only a few hundred meters thick doesn’t make much sense: its the bit people live in; its the bit plants grow in; its the bit that governs (sensible) heat transfer into the oceans and ice sheets.