Volcanoes contribute to climate change (rather than being caused by them), but mostly have a cooling effect. When they erupt to an extent that they inject sulfa

Volcanoes contribute to climate change (rather than being caused by them), but mostly have a cooling effect. When they erupt to an extent that they inject sulfates into the stratosphere, these sulfates seed cloud nuclei and increase cloud cover around the planet that reduces the IR energy from the sun. Sometimes a single volcanic eruption can have a dramatic cooling effect on the planet, like Mount Tambora in 1816, which triggered an extremely cold summer in Europe and North America: https://en.wikipedia.org/wiki/Year_Without_a_Summer https://en.wikipedia.org/wiki/Year_Without_a_Summer