Relationship Between Volcanic Eruption and Climate Change

A Tale of 2 Gases

• In addition to magma and ash, volcanoes produce two main gases that can play a role in climate change: sulfur dioxide and carbon dioxide. These gases are formed from interactions between the molten minerals and water vapor in the mantle of the Earth. As the magma rises, the change in pressure and temperature causes the gases to come out of the magma and into the atmosphere during an eruption.

Volcanoes Contribute to Global Warming

• You may recognize carbon dioxide as the gas that is most often discussed when the topic of climate change comes up. The carbon dioxide released by volcanoes does contribute to the overall carbon dioxide produced globally, and that increasing carbon dioxide has been linked to global warming. Interestingly, the relative impact of volcanic carbon dioxide is miniscule compared to anthropogenic, or human-generated, carbon dioxide. The relative amount of carbon dioxide released in a given year from all of the volcanoes on Earth is several orders of magnitude -- that is, 100 times -- smaller than anthropogenic carbon dioxide.

Volcanoes Contribute to Global Cooling

• Sulfur dioxide and ash introduced into the stratosphere by volcanoes have a cooling effect on the Earth. The sulfur dioxide reacts with water in the atmosphere to create a cloud of sulfuric acid droplets. This cloud of acid reflects sunlight that would otherwise warm the Earth. The impact is temporary as the cloud falls back to the surface as acid rain, a different type of problem. An example of the potential impact of sulfur dioxide would be how the eruption of Krakatau in 1883 caused the entire Earth to be approximately 1 degree Celsius (1.8 degrees Fahrenheit) cooler for three years.

From the Perspective of Geologic Time

• Current levels of volcanic activity might give the climate a tiny nudge in one direction or another, but historically volcanoes have had a much larger impact. Back in Earth̵7;s primordial days, around 2.5 billion years ago, there was much more volcanic activity, and the chemical reactions resulting from these eruptions created the bubble of breathable gas that protects and keeps the planet at a happy temperature for life. More recently, say 74,000 years ago, a mega-volcano erupted, taking out a 3,000-square-kilometer (1,200-square-mile) chunk of present-day Sumatra and cooling the Earth enough to possibly have triggered an ice age. It is theorized that enormous volcanic eruptions with the potential to impact climate for decades or even centuries have occurred throughout Earth̵7;s history.