There is a lot that comes from computer modeling and the ones being used today are far from being "simplified." Look at all the analyses that went into the chemistry of smog formation and through the use of catalytic converters in automobiles and a reduction in sulfur content in gasoline, the great smog crisis in the Los Angeles basin was solved. Nobody sat around waiting to see what mother nature would do. Another good example were the early theoretical calculations of the impact of supersonic aircraft on the Ozone layer (the exhaust is destructive). Back in the late 1960s, there was a lot of effort on the part of commerical aviation to develop supersonic passenger aircraft but the combination of high fuel cost and Ozone impact did this technology in.
You seem to have missed the point again, Alan. I'll repeat it. The success of modern science, and the degree of certainty about the accuracy of our theories, is dependent on our ability to make repeated tests and observe the results within a relatively short period of time.
Computer modeling might be a part of the process, and a very helpful part, but in the absence of practical testing to confirm the theoretical predictions, a degree of uncertainty remains, especially when the subject involved is enormously complex with a myriad of interacting and counteracting forces and influences, as is the case with the effects of CO2 on climate.
I'll repeat an analogy I made in a previous post, in case you missed it. If a Pharmacological company were to create a new drug, based upon computer modeling and experiments with chemicals and cell cultures in a laboratory, and were to claim with a high level of confidence that the new drug could cure or alleviate the symptoms of a particular ailment despite the fact that the new drug had not even been tested on mice, never mind humans, would you take the drug?
Of course, it would be illegal for such a drug to be marketed, and for good reason. There is usually a requirement that any new drug be tested on real creatures, such as mice, rats, guinea pigs and so on, before being tested on humans. From the following site:
https://www.ncbi.nlm.nih.gov/books/NBK24645/"Once a drug is shown to be effective in animals and to have a low incidence of side effects, it proceeds to safety assessment testing. These tests are conducted to evaluate drug safety in two different animal species, with animals receiving high doses of the new drug for 30 or 90 days. Animals are carefully monitored for side effects. After the study period, pathologists examine their organs for signs of drug toxicity. This drug safety testing in animals is carried out under guidelines mandated by law through the FDA. It is the last safety testing performed before the drug is given to people for clinical testing."All of those issues you mentioned above, analysing the effects on human health of smog and sulphur emissions, and the effects of aircraft exhaust fumes on ozone, can be examined through the normal processes of testing using the scientific methodology.
My point is that the effect on the global climate of relatively tiny increases of atmospheric CO2, are outside the parameters of the rigorous processes of the scientific methodology. Any certainty expressed about such effects are more to do with religion and/or politics than science.
It's time to get off this hobby horse and realize that more has been done to increase crop yield through plant breeding than will ever be seen from CO2 fertilization which will only play a minor part in things if at all.
What on earth are you talking about! CO2 is the most essential fertilizer of all. Without the fertilization effect of CO2 we'd all be dead. Nothing can grow without the presence of CO2. Even during preindustrial times when atmospheric CO2 was about 60% of current levels, the CO2 still had an essential fertilization effect, but not as great as today.
However, as with anything, too much can cause problems. CO2 levels of 1200 to 1500 ppm tend to have the maximum fertilization effect for some plants.
There are also studies which have investigated the effect of
reduced CO2 levels on plants. Here's a summary of such studies.
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2010.03441.x/pdf"Such studies have shown that the average biomass production of modern C3 plants is reduced by c. 50% when grown at low (180–220 ppm) vs modern (350–380 ppm) [CO2], when other conditions are optimal (Sage & Coleman, 2001;
Fig. 5). There is, however, variation in this response among C3 species (Fig. 5), as well as within C3 species, whereby reductions in biomass may vary by 40–70% among genotypes (Ward & Strain, 1997; Hovenden & Schimanski, 2000; Mohan et al., 2004). In addition, as [CO2] declines to 150 ppm, biomass production may be reduced by as much as 92%, as was observed in A. theophrasti (Dipperyet al., 1995; Figs 2, 5)."
