6000 years is not biblical. You don’t see that number in the Bible. 6000 years is merely calculation that some guy made in the 19th century. It’s beginngs roughly coincide with the beginning of the Jewish calendar. The jewish calendar in turn begins with the beginnings of the Sumerian civilization from which Abraham came —6000 years ago.
I might be remembering wrong but I believe Abraham was about 4,000 years ago. There were great upheavals in the middle east around that period. A few years ago Sunken Civ posted information about a mile wide meteor crater discovered in the Arab marshes after Saddam Hussein drained the marshes. Enemies of his dictatorship had used the marshes to hide in and the crater was found after the land dried out. I wonder how much devastation a meteor strike that big could have caused to middle east civilizations? Around 4,000 years ago was a time of significnt change in a number of middle east kingdoms.
Regarding climate change. The problem these days is that the change is occurring very rapidly. Too fast for many living creatures to adapt and survive. Normally climate changes much more gradually. However, large meteor strikes, huge volcanoes and the like can make for very sudden changes resulting in periods like “nuclear winter”. A huge volcanic event around 74,000 years ago was the eruption of Toba. It left a giant crater about 16 by 65 miles. Indonesia I think. It could have caused a nuclear winter around 10 years long. It appears to have lowered the humanoid population to only a few thousand mating pairs with significant effect on our DNA.
Yellowstone has had 3 huge eruptions, and many smaller ones. Big ones around 2 million years ago, 1.3 million, and 600,000+ years ago, leaving ash beds many yards thick over vast areas.
Note: I would leave links or more precise dates, but my old Cromebook is too uncooperative for me to risk moving back and forth while writing a comment, as all I have written could just disappear while shifting tabs.