A volcano is a tear in the Earth’s crust that allows hot lava, volcanic ash, and gases to exit from a magma chamber underneath the surface. Volcanoes are usually found where Earth’s tectonic plates are diverging or converging, and they can cause eruptions. Larger eruptions can also cause changes in the temperature of the atmosphere. It changes because the ash from volcanoes absorbs the Sun’s rays and cools the Earth’s troposphere. In the past, large eruptions have caused volcanic winter, and therefore the plants don’t grow, which causes hunger for people and other animals. Most of the volcanoes are underneath the water.
Volcanoes affect the climate by releasing gases and small particles like tephra or ash. The gas and dust mixture can both warm and cool the temperature on Earth. It depends on how the mixture absorbs the Sun’s light. Volcanic gases and dust that are released into the atmosphere fall rapidly over periods of days and weeks. So therefore, it doesn’t have a long-term impact on climate change. However, if the eruption is bigger and the gases are ejected into the stratosphere, then they have a bigger impact on temperature. During the eruption, different gases are released. If the gas is sulfur dioxide (SO2), it will cause global cooling. If the gas is carbon dioxide (CO2) and water vapor, it causes global warming.
Sulfur cools down the Earth’s climate, and it also depletes the ozone layer. The biggest impact on the climate comes when sulfur dioxide is converted into sulfuric acid. In the stratosphere, it forms small sulfuric aerosols. The sulfuric aerosol reflects the Sun’s rays back to space, and by doing that, it cools the Earth’s lower atmosphere, or troposphere.
There are few examples when the eruption has caused the average temperature to decline a little over half a degree (Fahrenheit scale), and the change lasted up to three years. For example, the explosion on Mount Pinatubo on June 15, 1991, was one of the biggest eruptions of the 20th century. This eruption injected 20 million tons of sulfur dioxide into the stratosphere. This sulfur cloud was the largest that has ever been observed since satellites were used for it. It is thought that it was probably smaller than the eruptions of Krakatau in 1883 and Tambora in 1815. They cooled the temperature on Earth by as much as 1.3 degrees Fahrenheit.
The eruption of Indonesia’s Mount Tambora was maybe the largest eruption that has ever been seen so far in the history of human civilization. It caused a snowfall in the United States and in Canada in June. The snowfall caused crop losses, food shortages, and increased death rates.
Carbon dioxide is the primary cause of climate change. However, the CO2 that is released into the atmosphere during the eruption of a volcano emits a lot less than humans do. Scientists have noticed changes in Earth’s temperatures when sulfur is released, but they haven’t detected any changes in temperatures when carbon dioxide is released. All current studies of global volcanic carbon dioxide emissions suggest that current subaerial and submarine volcanoes emit less than 1% of the carbon dioxide emitted by human activity. It has been suggested that in the geological past, the release of CO2 has caused global warming and, therefore, mass extinctions. Still, you shouldn’t underestimate the amount of CO2 that gets injected into the atmosphere by volcanoes. For example, in 1980, the eruption of Mount St. Helens vented around 10 million tons of CO2 into the atmosphere in less than 9 hours. Globally, humans are emitting in every 2.5 hours the same amount of CO2 into the atmosphere.
Global warming itself can also trigger more volcanoes to erupt. Since the temperatures are rising, it causes the melting of glaciers, and many of them cover active volcanoes. Mass melting reduces pressure at the surface, changing the processes in the Earth’s crust, for example, by bringing hot magma into contact with groundwater reservoirs. This, in turn, can trigger volcanic activity, as the whole system is connected. Warmer temperatures also let the gases and dust from volcanic eruptions rise higher, allowing them to spread faster over the globe.
In conclusion, nowadays, the contribution of volcanic CO2 emissions to the atmosphere is very small. It corresponds to about 1% of anthropogenic emissions. However, there have been times in Earth’s history when the release of CO2 caused climate change.
Sources:
https://en.wikipedia.org/wiki/Volcano
https://www.bgs.ac.uk/discovering-geology/climate-change/what-causes-the-earths-climate-to-change/
https://scied.ucar.edu/learning-zone/how-climate-works/how-volcanoes-influence-climate
https://www.usgs.gov/programs/VHP/volcanoes-can-affect-climate
https://www.ces.fau.edu/nasa/module-4/causes-2.php
https://www.euronews.com/green/2022/02/28/volcanoes-and-climate-change-how-do-they-connect
