The only constant in nature is change. We have been able to reconstruct the past using proxy data like fossils, isotopes, polar and glacial ice. They tell us our climate has varied considerably over the last 450 thousand years. The long glaciations (typically 100,000 years) are tied to variations in the sun-earth orbital parameters. They are followed by periods of 10-15,000 years of warmer interglacials.
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During the interglacials, global temperatures rise 18F but vary perhaps 2 degrees in millenium length ups and downs. Every great civiilization in history has reached its peak during the warm periods during the interglacials periods. Civilizations (Eqyptian, Minoan, Roman) thrived in the warm periods as crops could be grown more successfully in more places allowing for other societal advancement pursuits. They are tied to
peaks in solar activity. They have been followed by cooling periods (and civilization declines) as solar activity declined (as it did in what we call the little ice age or Maunder Minimum) with crop failures, famines and migrations.
See these two articles that suggest we may have reached our latest climate nadir in the Grand Solar Maximum’s Climate Optimum of the late 20th Century. The sun continues to show signs of going into a slumber like it did 200 or 400 years ago. A civilization decline may have also started and this set of global leaders and the UN if we don’t stop them will only make it accelerate down. For a time, the more opportunistic countries like China and India may advance but climate might have final say there too. See these two relevant stories for more.