Reader Jimbo advises in WUWT Tips and Notes about something Dr. [Kevin Trenberth] wrote that makes you wonder what he’s talking about when there are so many uses of the word “prediction” in the IPCC AR4. It also makes me wonder what the Economist author Oliver Morton was doing running a blog by Nature. Is there no separation between science journalists and science journals?
Trenberth suggests that after the last report “…the science is settled or done and now is the time for action.”. Here we are six years later, and another IPCC report is coming out on that “settled science” and there is no successor to Kyoto. I wonder how many times the word “prediction” will be used in the upcoming AR5?
Jimbo writes: I stumbled on a quote from [Kevin Trenberth] over at the Nature Blog dated 04 Jun 2007.
I thought I’d take a look because I was sure I had seen the IPCC use the word ‘predict’.
[My bolding throughout]
This subsection focuses on the few results of initial value predictions made using models that are identical, or very close to, the models used in other chapters of this report for understanding and predicting climate change.
…Some qualitative inconsistencies remain, including the fact that models predict a faster rate of warming in the mid- to upper troposphere which is not observed in either satellite or radiosonde tropospheric temperature records….
…The first IPCC Scientific Assessment in 1990 (IPCC, 1990) concluded that the global mean surface temperature had increased by 0.3 to 0.6°C over the previous 100 years and that the magnitude of this warming was broadly consistent with the predictions of climate models forced by increasing concentra- tions of greenhouse gases. However, it remained to be established that the observed warming (or part of it) could be attributed to the enhanced greenhouse effect. Some of the reasons for this were that there was only limited agreement between model predictions and observations,…
…However, models generally predict an enhanced rate of warming in the mid- to upper troposphere over that at the surface (i.e., a negative lapse-rate feedback on the surface temperature change) whereas observations show mid-tropospheric temperatures warming no faster than surface temperatures….
…..“historical” indicates the signal is taken from a historical hindcast simulation, “future” indicates that the pattern is taken from a prediction……
…Changes in the annual mean surface temperature were found to be highly significant (in agreement with previous results from Hegerl et al., 1996, 1997). The predicted change in the annual cycle of temperature as well as winter means of diurnal temperature range can also be detected in most recent observations….
…Estimation of uncertainty in predictions
The scaling factors derived from optimal detection can also be used to constrain predictions of future climate change resulting from anthropogenic emissions (Allen et al., 2000b). The best guess scaling and uncertainty limits for each component can be applied to the model predictions,……
… An example based on the IS92a (IPCC, 1992) GS scenario (whose exact forcing varies between models, see Chapter 9, Table 9.1 for details) is shown in Figure 12.13 based on a limited number of model simulations. Note that in each case, the original warming predicted by the model lies in the range consistent with the observations….
…The range is significantly less than one (consistent with results from other models), meaning that models forced with greenhouse gases alone significantly overpredict the observed warming signal….
…All but one (CGCM1) of these ranges is consistent with unity. Hence there is little evidence that models are systematically over- or under- predicting the amplitude of the observed response/ under the assumption that model-simulated GS signals and internal variability are an adequate representation (i.e. that natural forcing has had little net impact on this diagnostic)….
…Original model prediction under IS92a greenhouse+sulphate forcing…
…The SAR predicted an increase in the anthropogenic contri-bution to global mean temperature of slightly over 0.1°C in the five years following the SAR, which is consistent with the observed change since the SAR (Chapter 2). The predicted increase in the anthropogenic signal (and the observed change) are small compared to natural variability, so it is not possible to distinguish an anthropogenic signal from natural variability on five year time-scales….
…During the early summer season, October to December, both models predict drying over the tropical western side of the continent, responding to the increase in high-pressure systems entering from the west, with MM5 indicating that the drying extends further south and PRECIS further east….
…The IPCC commissioned a Special Report on Emissions Scenarios (SRES). Four “marker scenarios” representing different world storylines are used to estimate emissions and climate change to 2100 (IPCC, 2000). Table 16-1 summarizes these climate projections for the polar regions. In almost all cases, predicted climates are well beyond the range of variability of current climate. …
…The chemical and physical properties of aerosols are needed to estimate and predict direct and indirect climate forcing….
…Modelled dust concentrations are systematically too high in the Southern Hemisphere, indicating that source strengths developed for the Sahara do not accurately predict dust uplift in other arid areas….
…For summertime tropopause conditions the range of model predictions is a factor of five for sulphate. The range of predicted concentrations is even larger for some of the other aerosol species. However, there are insufficient data to evaluate this aspect of the models….