It's true that climate is too complex to predict well. Still, I haven't heard many global warming worriers warn about the threat of a new ice age. It's all about the world actually becoming warmer.
Given that, the real problem seems to be the speed. If it took 1000 years to raise 5 degrees, that might not be so bad. If it's 50 years, the necessary adjustments (to both humans and non-humans) might only happen with massive die-off.
But leaving aside the speed, it's not insane to notice that there is vastly more biodiversity in the tropics, than in the arctic. If you were designing a planet for humans to live on, a little warmer is a whole lot better than a little colder.
This doesn't mean that global warming is "good". But you shouldn't dismiss the positive changes out of hand, when evaluating the future pros and cons.
But leaving aside the speed, it's not insane to notice that there is vastly more biodiversity in the tropics, than in the arctic. If you were designing a planet for humans to live on, a little warmer is a whole lot better than a little colder.
You are operating under the assumption that warmer implies more tropics. I categorize this as wishful thinking.
We're all familiar with false popular memes that spread faster than they can be stomped out: You only use 10% of your brain. Al Gore said he invented the internet. Perhaps it doesn't surprise you that some memes in popular culture can't be killed. But does the same thing happen in science?
Most of you have probably heard of Broca's aphasia and Wernicke's aphasia. Every textbook and every college course on language and the brain describes the connection between damage to these areas, and the speech deficits named after them.
Also, both are probably wrong. Both areas were mistakenly associated with their aphasias because they are near or surrounded by other areas which, when damaged, cause the aphasias. Yet our schools continue teaching the traditional, erroneous story; including a lecture in 9.14 at MIT given in 2005. Both the Wikipedia entry on Wernicke's aphasia and the Wikipedia entry on Broca's aphasia are still in error; the Wikipedia entry on Wernicke's area has got it straight.
Is it because this information is considered unimportant? Hardly; it's probably the only functional association you will find in every course and every book on the brain.
Is it because the information is too new to have penetrated the field? No; see the dates on the references below.
In spite of this failure in education, are the experts thoroughly familiar with this information? Possibly not; this 2006 paper on Broca's area by a renowned expert does not mention it. (In its defense, it references many other studies in which damage to Broca's area is associated with language deficits.)
So:
References
Bogen JE, Bogen GM (1976). Wernicke's region—Where is it? Ann. N. Y. Acad. Sci. 280: 834–43.
Dronkers, N. F., Shapiro, J. K., Redfern, B., & Knight, R. T. (1992). The role of Broca’s area in Broca’s aphasia.
Journal of Clinical and Experimental Neuropsychology, 14, 52–53.
Dronkers NF., Redfern B B., Knight R T. (2000). The neural architecture of language disorders. in Bizzi, Emilio; Gazzaniga, Michael S.. The New cognitive neurosciences (2nd ed.). Cambridge, Mass: MIT Press. pp. 949–58.
Dronkers et al. (2004). Lesion analysis of the brain areas involved in language comprehension. Cognition 92: 145-177.
Mohr, J. P. (1976). Broca’s area and Broca’s aphasia. In H. Whitaker, Studies in neurolinguistics, New York: Academic Press.