How high must an eruption go to affect the climate?

To significantly impact the climate, a volcanic eruption typically needs to inject ash and sulfur dioxide (SO₂) into the stratosphere at least 10 kilometers (about 6 miles) high. This elevation allows the particles to spread globally, reflecting sunlight and leading to temporary cooling effects on the Earth's surface. Eruptions such as Mount Pinatubo in 1991, which reached this height, have demonstrated how such events can lower global temperatures for several years.