Expected cycles are caused by earth's variable orbit on distance from the sun. Other changes can be caused by volcanic and seismic activity. Human impacts are new as of the last several thousand years. Early hominids had no more impact than species like chimpanzees. It was the start of agriculture, domestication, and fire that started our human environmental impact. In 1890 marked what they think started our industrial revolution. The Industrial Revolution started unleashing more greenhouse gases into the atmosphere than would have naturally happen. Scientists have pieced together a record of Earth’s climate, all the way back hundreds of thousands of years or even millions or hundreds of millions of years by analyzing a number of indirect
