OK, here’s something I don’t get: a new paper in GRL by Russell Vose at the National Climatic Data Center suggesting the decrease in the diurnal temperature range slowed dramatically from 1979-2004. Maybe some of you climate types can ‘splain this?
(Backstory for non-climate wonks: The “diurnal temperature range” is the difference between the daytime high and nighttime low. My understanding, based on Karoly et al. in 2003 in Science, was that greenhouse warming would be expected to reduce the DTR by disproportionately increasing the overnight low temperatures. That’s exactly what I see happening in my own little corner of the world, with overnight lows warming a lot more than daytime highs. In other words, DTR is part of my day-to-day experience of global warming. It means my morning bike rides are a bit more comfy.)
Thanks for the links, John. No I can’t ‘splain this, but then I’m not really a climate type.
I don’t know if the linkage between reduction in DTR and increased greenhouse gases is quite as clear as you suggest, though I’m still catching up with the literature on this subject. For example the paper by Easterling et al (2003), whis mostly a global review of observations, suggests that increased cloudiness is involved, along with circulation and aerosol loading. And a recent analysis by Stone and Weaver (2003) of DTR trends in a climate model begins with the embarassing admission that the model underestimates the trend by a factor of 4!
More reading to do!
Easterling, D. R.et al. 1997: Maximum and Minimum Temperature Trends for the Globe. Science 277: 364-367. doi:10.1126/science.277.5324.364
Stone, D. ; Weaver, A. 2003: Factors contributing to diurnal temperature range trends in twentieth and twenty-first century simulations of the CCCma coupled model. Climate Dynamics 20: 435-445. doi: 10.1007/s00382-002-0288-y
Thanks, for these links, Mark. You’re right, it is a tad more intricate than my simplistic mental model.