[ClearCase_guy]

Two major volcanoes — El Chichon in 1982 and Pinatubo in 1991 — caused global average temperature to dip as a result of volcanic ash, soot and debris reflecting sunlight back into space.

Yes. Volcanic ash and soot can definitely cause cooling.
But it appears that the gigantic release of CO₂ from volcanoes does not cause warming. Because CO₂ doesn't actually do that. Oops.

[airborne]

Two major volcanoes — El Chichon in 1982 and Pinatubo in 1991 — caused global average temperature to dip as a result of volcanic ash, soot and debris reflecting sunlight back into space

Let's not forget Indonesia's Mount Agung, which is spewing tons of ash into the skies as we speak!