Every now and then some little obnoxious bunny goes nah nah global temperatures haven't risen in whatever years, everything is not known, natural variability is natural. Eli knows the patter and all the Rabett has to do is wander over to Kloor's to find the music should he forget
No, not the usual ABC blather from the seemers and deniers, but something that pops out at anybunny who actuall reads the thing.
there is substantial unforced variability on all time scales that can be examined, that is up to decadal times scales. Note that an unforced change in global temperature of about 0.4 C (o.3C, if the curve is smoothed with a 5-year running mean) occurred in one 20 year period (years 50-70). This unforced variability of global temperature in the model is only slightly smaller than the observed variability of global surface air temperature in the past century, as discussed in section 5. The conclusion that unforced (and unpredictable) climate variability may account for a large protion of climate change has been stressed by many researchers; for example, Lorenz (1968), Hasselmann (1976) and Robock (1978)They also looked at the spatial variation and variation with latitude and altitude
and indeed, the discussion of the paper's results for global temperature trends (the famous Figure 3) IS centered on the relationship of the predicted trends to natural variability and the variability in the model. It was the ability of the model to match natural variability, at least on a global and latitudinal scale that gave confidence in its performance when forced by increases in greenhouse gases and volcanic eruptions.The standard deviation ranges from about 0.25 C at low latitudes to more than 1 C at high latitudes in both models and observations. The model's variability tends to be larger than observed over continents; this arises mainly from unrealistically large model variability (by about a factor of 2) over the continents in summer as shown by the seasonal graphs of Hansen and Lebedeff (1987).
Interpretation of Figure 3 requires quantification of the magnitude of natural variability in both the model and observations and the uncertainty in the measurements. As mentioned in the description of Figure 1, the standard deviation of the model's global mean temperature is 0.11 C for the 100 year control run, which does not include the thermocline. The model simulations for scenarios A, B and C include the thermocline heat capacity, which slightly reduced the model's short term variability; however judging from the results from scenario A which has a smooth variation of climate forcing, the model's standard deviation remains about 0.1 C.There is more, but Ms. Rabett calls.