Volcanoes and Their Effects

by Carly Mullins

A note from the author...

Volcanoes have done great things for the earth, like create islands and fertilize soil. As a volcanologist, or someone who studies volcanoes, these are things I have to examine everyday to make sure people are educated about the effects of volcanoes. Throughout this flyer, you will be learning new things about volcanoes. The main thing you will learn is that volcanoes affect us through our climate. To fully understand this, you will also learn about specific volcanoes that have done this, how they affect the ozone, greenhouse, and haze effects, and how volcanic eruptions affect us in general.

How do volcanic eruptions affect the earth's climate?

Volcanoes affect the climate in many ways. According to the University Corporation for Atmospheric Research, “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”(UCAR). This shows that volcanoes change the climate by warming it. UCAR also state, "Most of the particles spewed from volcanoes cool the planet by shading incoming solar radiation. The cooling effect can last for months to years depending on the characteristics of the eruption”(UCAR). This shows that volcanoes cool the earth in addition to warming it. This happens when sulfur dioxide is emitted by volcanoes and cools the climate of the area (UCAR). All of these facts prove that volcanoes do in fact affect the climate. Next we will look at specific examples of volcanoes that affected climate in the past.
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This chart shows the changes in temperature after these volcanoes erupted. (Fasullo).

What are some specific examples of volcanoes that have affected our climate in the past?

Some examples of volcanoes that have affected climate in the past are Mt. Laki, Mt. Krakatau, and Mt. Pinatubo. Vic Camp explains, “Benjamin Franklin suggested that these cold conditions resulted from the blocking out of sunlight by dust and gases created by the Iceland Laki eruption in 1783”(Camp). This shows that Laki cooled the climate with dust and gases expelled during the eruption. Camp also describes the changes after Mt. Krakatau erupted, “For months after the Krakatau eruption, the world experienced unseasonably cool weather, brilliant sunsets, and prolonged twilights due to the spread of aerosols throughout the stratosphere”(Camp). This shows Krakatau also cooled the climate in the same manner as Laki did. Camp also explains about Mt. Pinatubo, “The Pinatubo eruption produced the largest sulfur oxide cloud this century. The data collected after these eruptions show that mean world temperatures increased by about 1 degree Centigrade over the subsequent two years”(Camp). This shows how greenhouse gases added to the atmosphere by volcanoes can raise temperatures over the entire earth. Now we will take a look at how volcanoes influence the ozone, greenhouse, and haze effects.

What is the influence of volcanic eruptions on the ozone, greenhouse, and haze effects?

The ozone, greenhouse, and haze effects are delicate climate tools that allow us to sustain life on this planet, and volcanoes effect them in many ways. One negative way they affect the ozone layer is stated by Vic Camp when he says, "It appears that volcanic eruptions can play a significant role in reducing ozone levels. However, it is an indirect role, which cannot be directly attributed to volcanic HCl. The particles themselves do not contribute to ozone destruction, but they interact with chlorine- and bromine-bearing compounds from human-made CFCs”(Camp). This means that volcanoes have an impact on the destruction of the ozone layer. Camp also says that volcanoes affect the greenhouse effect in this quote, "The small amount of global warming caused by eruption-generated greenhouse gases is offset by the far greater amount of global cooling caused by eruption-generated particles in the stratosphere”(Camp). This means that volcanoes really do not cause global warming. Finally, this quote explains the impact on the haze effect made by volcanoes, “Volcanic eruptions enhance the haze effect to a greater extent than the greenhouse effect, and thus they can lower mean global temperatures"(Camp). This shows that volcanoes positively affect the haze effect because they help reduce global temperatures, which helps prevent global warming. We have now seen how volcanoes affect climate, but now we will learn about more ways they affects us.
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How do these changes in climate affect us?

Volcanic eruptions affect us in other ways than just climate. One way they affect us is said by the USGS, "However, significant amounts of carbon dioxide, sulfur dioxide, hydrogen sulfide and hydrogen halides can also be emitted from volcanoes. Depending on their concentrations, these gases are all potentially hazardous to people, animals, agriculture, and property"(USGS). This is a negative effect that volcanoes have on people around the world. The USGS also states that volcanoes release high amounts of carbon dioxide, which, in large doses, can kill us. This is another negative effect on people. The USGS also explains that volcanoes can take away our resources in this quote, "In an ash-producing eruption, ash particles are also often coated with hydrogen halides. Once deposited, these coated ash particles can poison drinking water supplies, agricultural crops, and grazing land”(USGS). This adds to the list of negative effects that volcanoes have on people. In conclusion, volcanoes effect the climate and climate tools, which in turn affect us.

Carly Mullins

Carly Mullins is a volcanologist with a PhD in geology. She currently teaches at Harvard.


Text citations:

  • Camp, Vic. "How Volcanoes Work - Volcano Climate Effects." How Volcanoes Work - Volcano Climate Effects. Vic Camp, 10 Oct. 2000. Web. 24 Mar. 2016.
  • UCAR. "How Volcanoes Influence Climate." How Volcanoes Influence Climate. UCAR Staff, Web. 22 Mar. 2016.
  • USGS. "USGS: Volcano Hazards Program." USGS: Volcano Hazards Program. USGS Staff, 12 Feb. 2016. Web. 22 Mar. 2016.

Picture citations:

  • CVGHM. "Global Volcanism Program | Krakatau." Global Volcanism Program | Krakatau. Global Volcanism Program, 2013. Web. 04 Apr. 2016.
  • CVGHM. "Pinatubo." Global Volcanism Program. Global Volcanism Program, 2013. Web. 4 Apr. 2016.
  • Dr. Fasullo. "Lecture 31." Lecture 31. Colorado, Web. 01 Apr. 2016.
  • Hansen, Kathryn. "Sea Ice Patterns." Flickr. Yahoo!, 20 July 2012. Web. 05 Apr. 2016.
  • Smerdon, Jason. "Winter Eruption of Laki." Winter Eruption of Laki. Columbia University, Sept. 2013. Web. 04 Apr. 2016.