We know from archaeological ruins that there have been great civilizations in the past that seemingly disappeared from view. Some of those may have been decimated by disease or warfare, but some of them almost certainly were harmed by changes in climate such as multi-year droughts that may have made it impossible for them to survive. Here are two recent stories which discuss how previous civilizations ended due to long-term climate trends.
World Economic Forum: How climate change caused the world’s first ever empire to collapse
Phys.org: Maize-centric diet may have contributed to ancient Maya collapse