A volcano is a conical hill or mountain formed by material from the mantle being forced through an opening or vent in the Earth’s crust. Volcanic eruptions can affect climate in two ways, they release the greenhouse gas carbon dioxide, contributing to the warming of the atmosphere, and sulfur dioxide contained in the ash cloud can produce a cooling effect. Also, the volcanic ash cloud created by a volcanic blast can change interactions between the atmosphere and sun, affecting climate patterns. “When volcanoes erupt, they emit a mixture of gases and particles into the air. Some of them, such as ash and sulfur dioxide, have a cooling effect because they (or the substances they cause) reflect sunlight away from the earth. Others, such as CO2, cause warming by adding to the greenhouse effect.”
How does it work?
Ash generally remains suspended in the air for a period of time, increasing earth’s albedo. The ash prevents full sunlight from entering the earth, causing the temperature to cool immediately after the eruption. However, once ash disperses over the larger area, newly emitted greenhouse gases result in a marginal increase in average temperature. Since carbon dioxide is a major greenhouse gas, it traps heat radiated off of the surface of the Earth forming a type of insulation around the planet. In fact, according to UCAR (University Corporation for Atmospheric Research) Center For Science Education, the cooling effect can last for months to years depending on the characteristics of the eruption. Volcanoes have also caused global warming over millions of years during times in Earth’s history when extreme amounts of volcanism occurred, releasing greenhouse gases into the atmosphere. When Mount Pinatubo erupted in the Philippines June 15, 1991, an estimated 20 million tons of sulfur dioxide and ash particles blasted more than 12 miles and 20 Km high into the atmosphere. The eruption caused widespread destruction and loss of human life. This was one of the most powerful eruptions, There have been no significant eruptions since Mt. Pinatubo in 1991.