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
