Volcanism can both increase and decrease temperature. Volcanism can cause long term increases in average temperatures by releasing greenhouse gases, but at a very slow rate over millions of years. By comparison, human activities that release greenhouse gases have increased Earth’s average temperature just over the last few decades. Volcanic events can also cause short term cooling by increasing the amount of airborne particles that reflect sunlight in the atmosphere.
Although volcanic events have not caused the recent increase in Earth’s average temperature, eruptions have occurred throughout history and influence the Earth system in a variety of ways on various scales. Some of these ways include:
- Affecting the reflectivity of the atmosphere by releasing airborne particles, which can result in short-term cooling of the atmosphere.
- Airborne particles that affect air quality.
- Releasing greenhouse gases, including carbon dioxide and water vapor, although not enough to account for current warming trends.
- Affecting mountain building and formation of new land (distribution of continents and oceans).
- The displacement of human populations that live near volcanoes due to the release of lava, ash, and airborne particles.
Can you think of additional cause and effect relationships between volcanism and other parts of the Earth system?