For better comparisons between various studies as well as easier
communication of model results, it is preferable to use a common set of scenarios across the scientific community.
For any given metric, it is important to assess how good a test it is
of model results for making projections of future climate change.
The radiative transfer equations as
part of the modeled results have done a pretty good job of explaining the observed results but aren't exactly the same.
Nijssen, B., et al., 2003: Simulation of high latitude hydrological processes in the Torne - Kalix basin: PILPS Phase 2 (e) 2:
Comparison of model results with observations.
Comparison
of model results with the «known population» of radio - collared snow leopards suggested high accuracy in our estimates.
Proshutinsky, A. et al. including M. Steele and J. Zhang, «Arctic Ocean study:
Synthesis of model results and observations», EOS, 40 (4), 2005.
There is an important methodological point here — distrust conclusions reached primarily on the
basis of model results.
In it, Hansen re-iterated a number of his usual themes (the history of anthropogenic forcings, the
match of model results to the observed trends, the importance of the ocean heat content metric as a check on the planetary heat imbalance etc.).
Eighteen modelling groups performed a set of coordinated, standard experiments, and the resulting model output, analysed by hundreds of researchers worldwide, forms the basis for much of the current IPCC
assessment of model results.
Probably the best thing to show Congress (after a short explanation of those graphs) is a
video of the model results, as seen on Google Earth:
The important thing is whether the observed increase is in the range yielded by the models used to predict the future, and there it's clear that the spread
of model results covers the territory.
The assumption of independence leads to increased confidence in the «robustness»
of model results when multiple models agree.
However, if we don't include the effect of trace gases in the model we can't explain some of the observed features — just compare the earlier
graphs of model results with and without trace gases.
Answer: The growing
confluence of model results and the increasingly similar physical representations of the climate system from model to model may well look like sharing code or tweaking'til things look alike.
«Nonetheless, that study concluded that since both the surface and upper atmosphere trends were somewhere in that broad
range of model results, any disagreement between the climate data and the models was probably due to faulty data.
This allows
ensembles of model results to be constructed (see Chapter 9, Section 9.3; see also the end of Chapter 7, Section 7.1.3 for an interesting question about ensemble formation).
I don't want to put words into your mouth so I'll ask straight out: Are you looking for accuracy in the
comparison of model results to out - of - sample data?
Clement Kinney, J., W. Maslowski, Y. Aksenov, B. de Cuevas, J. Jakacki, A. Nguyen, R. Osinski, M. Steele, R.A. Woodgate, and J. Zhang, On the flow through Bering Strait: A
synthesis of model results and observations, Chapter 7, in The Pacific Arctic Region: Ecosystem Status and Trends in a Rapidly Changing Environment, J. M. Grebmeier and W. Maslowski (eds.)