Ash: While volcanic ash does contain some nutrients, the ash itself is very harmful to living organisms such as trees. When a volcano erupts, the ash tends to cover plant life and kill it. Also, if the ash is thick enough, it can shroud the atmosphere and block out the sun, causing a change in climate.

Acid rain: When a volcano erupts, sulfur dioxides are emitted into the atmosphere. These sulfur dioxides then can turn into sulfuric acids, causing acid rain. Acid rain of course, can be very harmful to the environment.

Environmental Effects

Greenhouse gases: When a volcano erupts, the gases inside are released into the atmosphere. Unfortunately, many volcanic gases are considered pollutants and they add to the greenhouse gases that are already there.