What is the main reason our climate has been changing the last 200
years?

Global Warming due to overpopulation, landfills, and pollution.

The rise of fossil-fueled economies over the past 200 years, and especially the accelerating CO2 emissions since the end of World War II, is clearly the cause of our mounting climate crisis.

Explanation:

answer; researchers typically cannot control people's sexual behaviors as would be necessary in an experiment;