The claim "El Chichon cooled the global mean temperature by 0.5 degrees C during the two years following the eruption." is false
Is the claim true?
The eruption of El Chichón in 1982 released a significant amount of volcanic ash and gases into the atmosphere. While volcanic eruptions can release large amounts of sulfur dioxide, which can contribute to the formation of sulfate aerosols that reflect sunlight, the overall impact on global temperatures is complex.
The cooling effect is usually temporary, and the net impact on global mean temperature depends on various factors, including the intensity of the eruption, the altitude at which the materials are released, and atmospheric conditions. The statement oversimplifies the situation; it is essential to consider the nuances of volcanic impacts on climate.