"Care to share your thoughts on whether you believe the science on climate change, specifically that we're heading to 2-4 degrees of warming this century? "
You are asking me what my thoughts are of a prediction that we are heading to 2-4 degrees of warming this century?
In the interests of brevity, I'll spare you the sanctimony of describing and defining the actuarial axioms that govern this kind of thing, and I'll summarise my thoughts thus:
Given the margins of forecast error, and the compounding effect over time of any such errors, I'm afraid my academic qualifications and professional experience don't leave me having much faith in such a prediction.
And that is not me calling into question the competence of climate scientists making that prediction; I am sure they are all really smart at their particular field of expertise.
Instead, my reservation stems from practical arithmetic reality that relates to the demonstrated limitations of modelling, predicting, and forecasting.
Because, when it comes to the making of long-dated forecasts, if you are out by just a teeeny weeeny bit in your input assumptions at Year Zero, by the time even Year Ten arrives the compounding effect of those incorrect input assumptions means that your forecasts to that point end up being inaccurate by a wide margin.
And by Year Twenty those forecasts become almost meaningless, due to the exponential rate of increase in the variance of the forecast against the actual outcome.
(Let alone by the time you get to Year Eighty!)
Not even the best climate scientist in the world can circumvent that statistical reality.
But don't take my word for it.
Ask any qualified and competent mathematician, statistician, actuary, scientist, etc., how much faith she or he would have in the veracity, dependability and reliability of conclusions derived from specific predictions, for a forecast period spanning several decades, relating to systematically complex, non-linear, multi-variate, chaotic environments with indeterminate number and type of second-order mechanisms.
In summary even 5-, 10-, or 20-year forecasts of natural phenomena are not worth very much.
80-year forecasts are really a load of horse manure, and no respectable scientist (or any other professional for that matter, including economists, actuaries, analysts, biologists etc.,) who understands what she or he is doing, would make them.
