The climate system is a coupled non-linear chaotic system, and therefore the long-term prediction of future climate states is not possible. [bold added]This statement appeared in the Executive Summary of Chapter 14 of the report produced by Working Group 1. (See the first bullet point on the right, page 3 of this 18-page PDF - or the third bullet point from the bottom here. The quote appearing in the book differs slightly from the IPCC version now online and reproduced above.)
The remainder of the page includes a great deal of gobblygook about the need to "project future climate changes" and the need to understand how probable some future scenarios may be when compared to others.
But there's no doubt about it. The IPCC admitted, a decade ago, that future long-term climate cannot be predicted. The system is chaotic. It is non-linear. It does not, and will not, behave the way we mere mortals expect it to.
So tell me again why we're scaring little kids witless by telling them there won't be a habitable world left by the time they grow up?
>> The big picture: the Y2K lesson
>> Ten-year snow prediction fails miserably
>> Global disaster is so 1976
>> We're always out-of-touch with the future