I want to change public concern from Global (GW) to Global Cooling (GC). Presented here are three arguments in favor of such a drastic shift — which involves also a drastic shift in current policies, such as mitigation of the greenhouse (GH) gas carbon dioxide.
My main argument relies on the fact, backed by historical evidence, that cooling, even on a regional or local scale, is much more damaging than warming. The key threat is to agriculture, leading to failure of harvests, followed by famine, starvation, disease, and mass deaths.
Also, GC is reasonably sure, while GW is iffy. The evidence, again, is historical — from deep-sea sediment cores and ice cores. Our planet has experienced some 17 (Milankovitch-style) glaciations in the past 2 million years, each typically lasting 100,000 years, interrupted by warm inter-glacials, typically of around 10,000-yr duration. The most recent glaciation ended rather suddenly about 12,000 years ago. We are now in the warm Holocene, which is expected to end soon.
In fact, we may have already entered into the next glaciation — as we can discover only in retrospect. (Past cycles suggest a very gradual cooling initially — with ice accumulation and a drop in global sea levels, a decrease in atmospheric CO2 into the cooling oceans and lowest temperatures occurring only much later in the cycle.)