Volcanoes: The 'X Factor' in Climate Change

Published on April 19th, 2010 | by

April 19th, 2010 by

Iceland’s Eyjafjallajökull Volcano eruption, showing volcanic plume and lava flow spreading northeast, spilling into Hrunagil Gully. Image was acquired on March 24, 2010, by the Advanced Land Imager (ALI) aboard NASA’s Earth Observing-1 (EO-1) satellite

Numerous volcanoes  presently active and erupting across the planet will impact short-term warming and climate change. Longer-term impacts are unknown.

On March 20, after nearly 200 years of dormancy, Iceland’s Eyjafjallajökull volcano started rumbling fiercely; then, the top exploded in a massive out-pouring of lava, pyroclastic debris and sulfurous smoke and ash. The eruption, which continues into its second week, has sent a great billowing plume of ash and gas high up into the stratosphere and across thousands of miles, blanketing a large portion of Europe.

Apart from the major disruption in flight traffic and the economy, the Icelandic volcano eruption promises in the short-term to disrupt upper atmospheric circulation patterns and temperatures, with an additional impact due to sulfuric acid “nucleation” and subsequent acid rain. But the medium to long-term impacts of continuous, or increasing, volcanic eruptions is a matter of on-going scientific debate.

The short-term effects of volcanic eruptions on the climate can be modeled and are fairly predictable, but potential, longer term impacts are still being debated.

The massive spewing of hot gases and ash may only last a few days, or a few weeks, but the impact of this natural pollution can persist for years, even decades. Currently, volcanic “ash” is getting attention due to its ability to harm/disrupt jet engine functioning.

What is volcanic “ash”?

Volcanic “ash” is actually a combination of fragmented pieces of rock and glass (originally formed from molten silica). The high temperature and pressure of the eruption can project  such ash many miles up into the troposphere and even into the upper stratosphere. Such ash can disrupt air current circulation and precipitation patterns.

Volcanic ash, like this from Mount St. Helens, is not really ash, but tiny jagged particles of rock and glass. (Image courtesy of the USGS)

What other climate-altering pollutants result from a volcanic eruption?

Volcanoes spew lots of noxious compounds and gases (like hydrogen sulfide, sulfur dioxide) which have varying impacts on the environment and climate.

When a volcano erupts,  massive venting of sulfuric gases into the atmosphere often follows, and this gas naturally converts to sulfate aerosols which can remain in the stratosphere for several years. These aerosol “clouds” can remain in the upper atmospheric and can block some of the Sun’s in-coming radiative energy, preventing it from reaching the lower atmosphere and planet surface.  This blocking of solar radiation also disrupts rainfall patterns which are driven by solar inputs. Aerosols can also absorb long-wave radiation deflecting from the Earth’s surface. The short-term result from all this is a cooling of the upper atmosphere but with some heat trapping nearer to the surface.

Mount Pinatubo, June 13,
1991 (Image courtesy of NOAA)

Climate modeling following the eruption of Mount Pinatubo in the Philippines in 1991 (using both aerosol and non-aerosol starting inputs) produced a general cooling of the troposphere (the band of the atmosphere where most clouds circulate), but also, the models yielded a pattern of winter warming of surface air temperature over the Northern Hemisphere. Dual effects such as these complicate longer-term climate impact predictions.

To what extent this tropospheric cooling is mitigated or “canceled out” by other sources of warming, such as from solar activity, build-ups of CO2 and other greenhouse gases, and long-term variation in Milankovitch cycling (currently only one cycle, precession, favors glaciation), depends on the timing and duration of all these factors,  and makes for the highly complex science that is climatology.

Is volcanic activity a trigger of glaciation? Ancient volcanic debris data is used to calculate past glacial period.

There is some evidence from paleogeological studies that shows a correlation between vulcanism (numerous, on-going eruptions) and global cooling and glaciation. For example, in a recent study by Macdonald et al (Calibrating the Cryogenian, Science, 5 March 2010), a volcanic “tuff” (a type of rock composed of consolidated volcanic ash, often from undersea venting) was found embedded in ancient (716.5 million year old) glacial deposits, coinciding with the onset of the Sturtian glaciation period in the Neoproterozoic era. This glaciation–also known as the Cryogenian–is now claimed by the authors to have been global in extent. Whether extensive vulcanism triggered a pronounced planetary cooling, and consequently, the Sturtian (global) glaciation, is not clear from the geologic record; more study will need to be done.

How the biosphere responded to this glaciation phase, or phases, is also a puzzle, as micro-fossil evidence in accompanying strata also show an outward expansion (“radiation”) of eukaryotes (simple lifeforms possessing a nucleus), which are often primary producers and the basis of future food webs.

What is the current state or extent of volcanic activity around the globe?

According to NASA’s Earth Observatory Natural Hazards service, utilizing imaging from two satellite sources ( ALI {EO-1} and MODIS {terra}) there are several active volcanic sites around the planet:

The Kamchatka Peninsula,  the northwestern edge of the Pacific Ring of Fire, is one of the most volcanically active regions on Earth.  Four of these  volcanoes—Shiveluch, Klyuchevskaya, Bezymianny, and Karymsky—are erupting currently (as of early April 2010).

Klyuchevskaya volcano continues to be active—emitting steam, ash, and lava—in early 2010.

Kilauea volcano continues to erupt, with the centers of activity at Pu‘u O‘o and Halema‘uma‘u Craters.

Additional reference for this article found here.

Top photo: (Iceland volcano) NASA, Earth Observatory
Middle photo: (volcanic ash) USGS
Bottom photo: (Mount Pinatubo eruption) NOAA

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  • JCzar

    Our primary power source is the Sun. If less of its energy reaches the surface, things get cooler. The blanket effect does not in any way shape or form add energy to our little sphere. That being said, the long-term affects of the blanket of reflective material floating in our atmosphere are undeniable; less energy reaches the surface. Will that change anything when it comes to global temperatures? Yes, it will. Will it be significant? Doubtful. Argue global warming all you want. Just don’t confuse facts with speculation. If one of these volcanos erupts every year for the next 10 years, we’ll have long lasting changes.

  • Michael R.

    I anticipated some reader using this article to “justify” an anti-climate change viewpoint (preconception)…my point in writing it was generally to emphasize the complexities and mitigating influences in warming and climate change predictions, due to “unpredictable’ events like volcanic eruptions…not to say “Hey, see, nothing to worry about…”

    Volcanic eruptions disrupt precipitation (by blocking sunlight, the “engine” that drives precipitation) patterns and air current circulation patterns…which, if sustained over a longer period of time, will complicate climate modeling and predictions….but it may be a ‘forest for the trees” thing…the over-all trend is warming and climate change,; vulcanism may simply provide short-term, transient aberrations…

    It would take a good deal more volcanic activity to have any major, long-term impact on the global climate.

    Currently, geo-engineering schemes involving sulfur dioxide (or actual sulfuric acid) are being considered (knowing that global seeding of the atmosphere with either will have an environmental impact on crops, waterways, and marine systems).

    Thank you Zach and Kristian for being the rear guard on this.

  • KristianJL

    Volcanoes do not negate the science behind climate change data. This will only complicate or increase the effects of carbon and methane emissions. Those who try to politicize science only do so because they are afraid of the implications to their selfish lives.

  • Meme Mine

    Volcanoes prove that nature is in charge, not my SUV so you warmies may as well tax volcanoes while you are busy trying to scare my kids.
    You modern day witch burners will be cursed in history for this enviro WMD false war.

    • Zachary Shahan

      i have not looked into it in depth (yet), but heard that the reduced CO2 emissions from grounding all those flights were much more significant (regarding climate change) than the emissions from the volcano. not sure, but something to look into

  • Special K (NJ)

    Quite on schedule the Icelandic natural disaster
    Is attributed to global warming and/or climate change,
    Or the latter’s rate is said to be increased by the former:
    Of “Having one’s warming cake and eating it, too”, in the expected range.