Volcanoes,erosion,chemical weathering
I would sayyyy probably 2
Gases and solids injected into the stratosphere circled the globe for three weeks. Volcanic eruptions of this magnitude can impact global climate, reducing the amount of solar radiation reaching the Earth's surface, lowering temperatures in the troposphere, and changing atmospheric circulation patterns.
Because of high birthrates and low deathrates.... the one child policy however slowed this down significantly!
hope this helps!!
