The computer models have been the backbone of climate change science, a lot of the IPCC predictions have been made on the basis of CMIP models.
Without the models scientists would have to rely on empirical evidence, and so far no empirical evidence has been able to separate natural climate from CO2 changed climate.
Not sure what can be done, as the models have failed dismally in matching nature, some say they are useful in understanding the processes, but I dont see how you can trust what they say about the processes, when they cannot match reality.
I am sure they could be adjusted so their results are more in line, but all that would do is to downgrade global warming to non problem status.
I'll repeat my answer from his version of the question.
If computer simulation models and similar tools were permanently abandoned, then climate scientists would... be more vague and general about what they think is going to happen.
But neither the fundamental principles nor the general conclusions would change. Models are just tools, to figure out how a general principle (like "increased CO2 will increase the Earth's temperature") will work out, specifically and in detail, in an adequate simulation of the real world. It's a way of testing and refining theories, but it is not essential to the theories themselves.
I think the problem is that sceptics set a hurdle for science. Kano, for example, says there is no empirical evidence to separate natural climate from CO2 changed climate. And he is absolutely correct. However, there is virtually no way of directly, and experimentally, demonstrating such a thing. So what the sceptics are doing is saying 'I want X experiment to be performed before I accept, even though X experiment is impossible'.
For example, let's suppose we could track every single CO2 molecule humans released into the atmosphere, tagged each one with a nano-sensor to measure the energy incident on that molecule, the energy radiated, and the energy absorbed in terms of vibrational or rotational modes, showed that the total energy retained in the atmosphere by all those CO2 molecules was X, warming it by Y. The point is, the sceptics are big on whinging about the science but consistently fail to offer any suggestion of what experiment scientists could do that would satisfy them.
We know that CO2 levels are now higher than at any point in the last 650,000 years. We know the rate of increase is unparalleled in that time frame. We know that this rise coincides with the time we started pumping large quantities of CO2 in to the atmosphere. Scientists know that correlation is not causation, but the fact that isotope ratios measured in the atmosphere and in plants are consistent with CO2 produced by burning fossil fuels is solid experimental evidence that most of the additional CO2 in our atmosphere has been caused by us. Estimates of the amount of carbon fuels we've burnt, combined with estimates of the lifetime of that CO2 in the atmosphere, allows us to confirm that the increase we've observed is consistent with the volumes of the gas we've pumped into the atmosphere.
Over the past 150 years or so, instrumental records have shown the global average temperature has been rising. This has been added to by land, sea, air, and space-based measurement systems, all of which show rises in global temperature. The rise in temperature causes a rise in sea levels due to thermal expansion and we've also measured this to be happening by gauges and satellite. Tree lines in the northern hemisphere have been advancing farther north for decades. Plants are flowering earlier. Typical migration dates of birds from the north to the south are happening later. Glacial melt rates, particularly of Greenland, are increasing and have been measured. Arctic sea ice has been thinning for decades. Locally, meteorologists are seeing changes to well-established patterns with, for example, a greater frequency of periods deviating from the norm in terms of rainfall or drought.
When you combined these two, there is little doubt that a) the CO2 rise is human induced and b) the temperature of our planet is increasing. Now we know CO2 is a greenhouse gas, so factoring in the impact on heat retention from the additional CO2 we've added, and doing the calculations using the 'models' demonstrates that it is, at the very least, plausible that the temperature rises we've observed and the CO2 levels we've created are linked.
We can't directly prove this by experiment because such an experiment is impossible. We can't track each CO2 molecule. So insisting that an experiment be performed that directly proves CO2 and the temperature rise are linked before you accept AGW is irrational. How do we do such a thing if we can't travel back in time to perform the imaginary experiment in the past? What we can do is look for other possibilities. The only factors that could account for a global warming of the magnitude we've observed is the sun or changes in the earth's orbit. Neither has been shown to be consistent with the observations. Both were ruled out more than two decades ago.
Therefore, the models are the best, yet imperfect, solution we have available to us to investigate the future impact of CO2 on our climate. The fact that they are imperfect does not negate the empirical evidence showing the CO2 rise, the temperature rise, or the failure of natural causes to explain the observations. The conclusions of climate science (the planet is warming and we're responsible) is not dependent on the models.The models are predictions that allow us to plan in the absence of absolute total information, which we can never obtain. They're the best we can do at the moment and whinging that you'd like something absolute when that doesn't and can't exist is a bit silly.
Some time ago people tried to predict the future with crystal balls, goat entrails, and chicken bones. Today they do the same thing with computers. No one can predict the future and science isn't about predictions, it's about calculating. Still no one knows if it will be warmer or colder in 5 years.,
Question from Hey Dook, posted so everyone can answer.
