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One of the interesting aspects of the climate change debate is the utter confidence of the predictions made. I'll give an example from the IPCC's advice concerning future global warming.

For example, the most important parameter in climate change, temperature sensitivity - how much long term global mean temperature increases with a doubling of CO2 (and equivalent in other greenhouse gases) is thought presently to be between 1.5 C and 4.5 C per doubling by the IPCC. Similarly, they present currently a rise of 1.5 C from pre-industrial age as a feasible stopping point (for example, here), if one mashes on the economic brakes. But that ignores that we probably are already over that threshold even at the average 3 C per doubling. For example, if we take pre-industrial CO2 as 280 ppm and assume that non-CO2 emissions increased at same rate, and then 3 C per doubling, then 1.5 C of warming hits at roughly 396 ppm (which would be 2012). Given the significant chance allegedly of higher sensitivity than that, it means that we have a rather high chance of being way past stopping 1.5 C of warming.

So what happens if they're off the other way? At 2 C, I'm getting two decades and at 1.5 C almost five decades before that threshold is exceeded (using a ok fit quadratic equation 0.0145*t^2 + 0.73*t + 315 in ppm CO2 where t is number of years past 1959 - meaning increasing CO2 concentration for the time span in question).

The most interesting aspect is what happens if we stop at a much higher threshold than advised by the IPCC. If we stop at 4 C threshold instead, that's reached in three and a half decades at the extreme 4.5 C per doubling, eight decades at 3 C per doubling, 150 years at 2 C per doubling, and 230 years at 1.5 C per doubling. There is plenty of time for things to happen (such as the entire world attaining developed world status) at those longer times.

Adaptation along with a high threshold and a low temperature sensitivity means a very long period of time till action needs to be done. Let us also note here that the short term sensitivity, which can be measured with reasonable accuracy, is more like 1.5 C per doubling, maybe less (if the Sun is more of a contribution to global warming than presently alleged).

So the IPCC, the supposed consensus of climatologists, has a peculiar certainty about what the future climate will be like, namely, that long term temperature sensitivity will be very close to 3 C, despite their own claims on the matter, that 1.5 C threshold is really important to not pass despite poor justification for that claim, and finally, that adaptation measures aren't important to consider at present, even though by their own reasoning, there's a good chance we're to the point where adaptation is unavoidable, even if we were to completely halt CO2 emissions tomorrow.

It's this sort of mixed message, here where a supposedly science-based organization presents a very narrow scenario in contradiction of their own data and knowledge - but there are many other examples, that leads me to doubt the honesty and integrity of this entire movement. Why should we accept a pig in a poke and assume they're telling the truth about temperature sensitivity and the harm of various temperature thresholds, when they contort their own science to present a very particular narrative? For example, why should I assume 3 C per doubling and 1.5 C of warming rather than 2 C per doubling and 4 C of warming?

Ultimately, this culture needs to be changed.