Ice Age

Jerry Pournelle comments on the ice age.

We are back to ice: there is now serious but not conclusive evidence, convincing to some, that the only thing preventing a new ice age is CO2; and we are busily removing CO2. Now admittedly the serious studies anticipate this happening over a fairly long time period. On the other hand, all the historical evidence is that ice ages happen fast. England went from deciduous trees to frost plains to ice in well under a hundred years, and to kilometers of ice in another hundred. There is similar evidence from lakes in Belgium. When the ice comes, it comes fast.

Note that climate changes are odd. A few miles south of the ice wall average temperatures were not all that much colder than they are now. The ice didn't extinguish life; but it sure made large parts of Europe and North America uninhabitable. Ice is a [far] greater threat than a few degrees of temperature rise between [now] and the end of the century. Prudence demands that we continue to look at the CO2 rise. Prudence also demands that we not wreck the global economy in order to play carbon restriction games that, according to even the most optimistic models, will have only a tiny effect on the average temperature of the Earth in 2090.