[.cnI redruM]

>>>>>>>Those changes took place over longer time-frames than the Industrial Age (mid 1800s to present) that is the time-frame of concern now.

As they used to say in the Hertz commercials....not exactly. Chapter 1 of "A Distant Mirror", a history of 14th Century France authored by Barbara Tuchman, makes the exact opposite point regarding temperature decreases in the Late 13th and Early 14th Centuries that significantly altered the growing seasons and biotic potential of agriculture in Northern France.

Tuchman posits a domino effect starting with climactic change which leads to lowered harvests. This than causes malnutrition which degrades the immune systems of people than living in Norman France. This lowered immunity than makes the people susceptible to the diseases carried by travelers and traders traveling frequently between Isle De France and Calais.

Tuchman points out explicitly that these people had probably been exposed to at least some vector carrying a disease similar to Bubonic Plague since trade had returned to the North of France has a positive aftereffect of the nascent Italian Renaissance.

It's only through planting the axiom of weakened human immunity, brought about by sudden and accelerated negative forcing, that explains why 1/3 of the population of Northern France would suddenly succumb to a disease that they previously resisted by-and-large for the better part of a century.

[cogitator]

As they used to say in the Hertz commercials....not exactly. Chapter 1 of "A Distant Mirror", a history of 14th Century France authored by Barbara Tuchman, makes the exact opposite point regarding temperature decreases in the Late 13th and Early 14th Centuries that significantly altered the growing seasons and biotic potential of agriculture in Northern France.

I'm afraid I don't see the relevance. The original poster inquired as to what factors initiated and terminated the glacial cycles that we refer to as "Ice Ages". My response was that the initiation and termination is primarily due to Milankovitch forcing. The Milankovitch cycles operate on several-thousand-year time-frames. I.e., the decrease in insolation leading to a glacial epoch due to Milankovitch forcing will take place over a period of several thousand years. There are feedbacks; as the insolation decreases, there can be a slow increase in the snow/ice cover. This increases the Earth's albedo, reflecting more sunlight back into space, leaving less to warm the Earth. Etc. These processes can "accumulate" slowly, to a tipping point where there is a fairly rapid (over a period of several hundred years) change in climate regimes, from warm to cold or vice versa.

So while your point was interesting, I'm not sure how it related to my point.