The Role of Volcanism in Climate Change
1- Relation between volcanism and climate change: A general overview of volcano-climate forcing
1a- Short term volcanic events
The first way we can see a relation between volcanism and climate change would be by looking at the short-term events with which volcanic activity could cause climate change. Short-term volcanic events can happen when gases are ejected in the atmosphere in an explosive manner but the most important aspect of short-term events would be weather or not the materials and gases ejected by the volcano would have reached stratospheric injection. Other names for stratospheric injection would be volcanic aerosol clouds or dust veil. The next figure represents how a volcanic eruption would have a short-term impact on climate change.
Figure 1: Volcanic inputs in the atmosphere
The main impact of aerosol clouds would be that the planetary albedo would be increased a lot by the “backscattering incoming solar radiation” (Cooper et al., 2018, p. 239). This would cause the surface of the Earth to cool down. The main area on Earth where we could find volcano eruptions that would play a major role in the cooling of the planet would be at the Equator.
1b- long term volcanic events
Another type of events with which volcanoes can have an impact on climate change would be the long-term events. Even though most of the volcanic aerosols come from short-term events, they could also come from long-term explosive eruptions. These long-term effects would usually occur in the Tropics and have as consequences weather events such as the El Niño cycles as well as the El Niño / Southern Oscillation. Researchers think that these two events would be results of the long-term events caused by volcanism but they are not completely sure yet. Research is still being done on this matter.
1c- volcanic responses to climate change
When we look at the impact of volcano eruptions on climate change, we usually look at the mechanism that links volcanism and climate change together. The mechanism in question would be the unloading effect. The best place to see the unloading effect in action would be Iceland. During this mechanism, we can see an uplift that is the response to deglaciation. The more and the faster the pressure goes down undergrown; the bigger will be the extent of the of the decompression melting of the mantle. This would mean that the melting of the glaciers in Iceland would allow the magma to make its way to the surface because its temperature would be rising. An example of the decompression and its causes can be seen in figure 2.
Figure 2: Impact of the pressure and the temperature on the decompression geotherm (Cooper et al., 2018, p. 242).
When scientists look at the link between volcanic activity and climate change, they often would use two types of tools. The first tool they would use would be tephrochronology and the cryptotephra. Tephrochronology is mostly useful to look at the number of volcanic eruptions that happened in the past at a specific location. The main reason for this is that tephrochronology is a type of chorological framework that uses paleoenvironmental as well as archeological records. The second tool, cryptotephra (which is also known as non-visible volcanic ash), can be used to understand processes and characteristics of volcanic eruptions that happened in the past.
2- Relation between volcanism and climate change: A more detailed view
2a- bipolar correlation of volcanism with millennial climate change
The first thing that could come to our mind when we look at the relation between volcanism and climate change in more details would be the bipolar correlation of volcanism with millennial climate change. When we look at this type of correlation, it is possible to see that volcanic eruptions can cause climate change. Furthermore, climate change can also cause volcanic eruptions. In the two cases, the type of climate change that is of question here is millennial climate change.
The main way that volcanic eruptions can cause climate change would be if the ashes, that are a product of the eruption, find their way to the ground surface that could be covered in ice or snow, we could see a reduce in the albedo effect. In this case, because the albedo is being reduced, this would mean that the ice and snow would melt more. This melting would be even more true if the eruption of the volcano in this situation would happen during the summer months.
Another way that volcanic eruptions can impact climate change would be with the aerosol components that are ejected in the atmosphere during said eruptions. These aerosol components would reflect the sunlight back to space thus stopping it from reaching the surface of the planet. The aerosol components that it is question here are SO2 and H2S. These aerosol components could have a major impact on the Earth’s climate for months at a time even for several years.
Volcanic eruptions do not simply impact the climate because of the substances that they eject in the atmosphere. The impact that they have on the climate tends to change from area to another. This means that depending on where the volcano is, it will have a bigger or a smaller impact on the climate.
Earlier in this section, it was stated that volcanic eruptions could cause climate change. The reverse is also true meaning that climate change could cause volcanos to erupt as well. The best time period that would explain this fact would be the Holocene. To explain this, Zielinski et al. (1996) cited by Bay et al. (2004) explains that the moments in time that would have the most important volcanic activity would often happen during periods when the climate was changing. According to Maclennan et al. (2002) also cited by Bay et al. (2004), the main reason why the deglaciation would cause volcanic eruptions in places such as Iceland was that there were increased melt generation rates situated in the more superficial parts of the mantle.
Another way that volcanic eruptions could be provoked by climate change would be the atmospheric jolts that have an impact on the Earth’s rotational and angular momentum. Another way would be the effect of loading and unloading of the ice-sheet on the distribution of mass of planet Earth. This unloading effect brings the researchers to wonder if a good part of the volcanic activity that has been happening on the Earth would have been impacted by sea level changes or other large impacted environment changes.
The two main types of volcanic eruptions that researchers know about are the high-latitude volcanic eruptions and the low latitude volcanic eruptions. Each of these types of volcanic eruptions impacts climate change in specific ways.
2b- climate responses to low-latitude volcanic eruptions
In the case of the low latitude volcanic eruptions, they happen at the equator. During this type of volcanic eruption, they particles that are ejected from the volcano rise in the atmosphere with the warm air that is rising too. Once the particles are in the atmosphere, they stay there for a period of time during which they will have an albedo effect on the Earth. The albedo effect would cause a global cooling of the planet.
2c- climate responses to large high-latitude eruptions
In the case of high-latitude volcanic eruptions, these eruptions would happen in higher latitudes where cool air is descending from the atmosphere. This would mean that the volcanic particles do not rise as much and stay airborne as long as the volcanic particles of low-latitude volcanic eruptions. Also, the cooling effect of the high-latitude volcanic eruptions is not as strong or strong lasting as the cooling effect of the low-latitude volcanic eruptions.
While high-latitude and low-latitude volcanic eruptions are the main types of volcanic eruptions that have an impact on climate change, another more specific type of volcanic eruption that could impact climate change would the synchronous volcanic eruptions.
2d- synchronous volcanic eruptions and abrupt climate change that may be linked by the stratospheric ozone depletion
Synchronous volcanic eruptions are usually associated with abrupt climate change events. A good example of this type of eruption and its impact on climate would be Mount Takahe, which is situated in Antarctica. The main reason why this synchronous volcanic eruption caused abrupt climate change is that it is thought to have caused the stratospheric ozone depletion which cause the deglaciation in the southern hemisphere. Scientists who studied this volcanic eruption think that the depletion in the atmosphere " triggered large-scale atmospheric circulation and hydro climate changes similar to the modern Antarctic ozone hole, explaining the synchronicity and abruptness of accelerated Southern Hemisphere deglaciation" (McConnell et al., 2017, p. 10035).
The main ways that synchronous volcanic eruptions would have impacts on the atmosphere would be by the particles that they eject in it. The particles that this type of volcanic eruption would usually eject in the atmosphere would be mainly sulfur. The scientist discovered that Mount Takahe had a major impact on the stratospheric ozone by discovering evidences of volcanic materials in the sulfur isotope anomalies they found in cores they took of that volcano.
Another evidence that researchers found that proves synchronous volcanic eruptions would have impacts on the atmosphere would be the enhanced tropospheric UV radiation that could be found as well in the sulfur isotope anomalies.
In contrary to the high-latitude and the low-latitudes volcanic eruptions that caused a cooling of the surface of the Earth, the synchronous volcanic eruptions caused a warming of the surface of the planet.
2e- volcanic gas (sulfur dioxide) impacts climate change
Until now, in this paper, we have often discussed about sulfur impacts the Earth’s climate in a general sense when it is ejected from volcanoes. Now we will look at sulfur dioxide in more details to see its role in climate change.
Looking at the different chemicals that can be found in volcanoes, it is possible to see that the most important one would be in fact sulfur dioxide. The chemical is found in the majority of the volcanic eruptions that happened on Earth over time and that are still happening today. According to researchers one of the main effects that sulfur dioxide would have on the atmosphere would be that it “overdrive the oxidizing capacity of the atmosphere resulting in very rapid warming (Ward, 2009, p. 3188)."
The sulfur dioxide is also known be often seen with the CO2 concentration in the atmosphere. The main reason for this would be that the CO2 would often have an impact on the warming of the Earth only after the SO2 has greatly impacted the warming of the planet.
Even though sulfur dioxide is usually known to warm up the surface of the Earth during volcanic eruptions. Its effect change depending on its rates of emission and depending on the eruption rates of the volcanoes. These changes can be seen in the following figure.
Figure 3: The four rates of sulfur dioxide (SO2) (Ward, 2009, p. 3189).
Looking at the table, we can see that when sulfur dioxide is at its lowest emission rate, it would cause cooling and draughts that could go on for approximately ten years. In the case of a moderate rate of sulfur dioxide emission, the ejection of these particles would cause a cooling that would go on for a few years.
Now if we continue to look at figure 3, we can see that when high amounts of sulfur dioxide are ejected from a volcano into the atmosphere during an eruption, we will not be looking at any cooling anymore but more at a warming of the Earth. This type of warming would be in fact what we know today as Global warming. If extreme levels of sulfur dioxide would be ejected from a volcano during an eruption, it would cause extreme global warming and even mass extinction events in some cases.
3- History of significant volcanic eruptions
3a- volcanic activity during the Cenozoic era
When we look at the links between climate change and volcanic eruptions during the geological time periods in the past, we can see that one of the important periods would be the Cenozoic era and its epoch named Eocene. When it comes to understanding why and how the climate was warming during this period, researchers have discovered that the warming in the beginning of the Eocene epoch which is part of the Cenozoic era.
During the Eocene, the main evidence that researchers could find to link climate change (warming events) to volcanic activity such as eruptions would be the greenhouse effect CO2. According to scientists, the volcanic activity that played a role in the greenhouse effect CO2 would have been situated in the mid-ocean ridges.
One of the main things that the Green-house effect of CO2 would have done to the Earth’s climate would be that it would have played a role in the warming optimum by releasing in the environment an important amount of Columbia River basalt. The Columbia river section that we are referring to here would be from Oregon to Idaho. Another area where a release of basalt due to the greenhouse would be in some Japanese islands.
Generally, the type of volcanic eruptions that happened in the mid-ocean ridges tended to decrease in intensity during the Cenozoic. The volcanic activity that was going on at a subduction zone during the same period is thought to no have been synchronised with the volcanic activity that was happening at the mid-ocean ridge.
3b- the Little Ice Age
Another significant period that we can think about when we think about time periods that had volcanic eruptions that impacted the climate of the Earth would be the Little Ice Age. The events that caused the caused the Little Ice Age (and the change in the climate) mostly happened during the thirteenth century.
During this period, we could see summer seasons that were cooling down drastically. One of the reasons why these summers were this cold was because of the sea-ice / ocean feedbacks. According to researchers the main reason the Little-Ice Age was so significant was because of the feedbacks kept the climate cold even after the aerosols and the rest of the chemicals were no longer in the atmosphere.
Often when we think of climatic changes due to volcanic eruptions, we usually think of one specific volcanic event. In the case of the Little Ice Age, it is multiple eruptions that made the Little Ice Age what it is.
The main consequences of the volcanic eruptions that occurred would, according to researchers, would be the "freshening and vertical stratification of the North Atlantic subpolar gyre, reducing open ocean convection and thus weakening the Atlantic meridional overturning circulation" (Miller et al., 2012, p. 4). Another significant consequence of these volcanic eruptions during the ice surface that was expanding. The expansion of the ice cover was also caused by the albedo effect of the eruptions.
3c- the Eldgjá volcano eruption and its link to climate change
Another important volcanic eruption that would link climate change and volcanic eruptions together would the one that occurred at the Eldgjá volcano in Iceland during the Common era. The type of volcanic eruption that occurred was a lava flood eruption.
During the Eldgjá volcano eruption, 19.6 km3 of magma found its way into the environment which caused approximately 30 to 70 tera-grams of sulfur dioxide to be ejected in the atmosphere. The eruption of the volcano that is of interest for this paper would be the one that happened in 939 CE. Even though the volcanic eruption happened during that year, it still started little by little seven years and a half earlier. The eruption did not only have repercussions in Iceland. The repercussions could be felt as far as some European countries such as France, Switzerland, Belgium, the Netherlands and even as far as China.
When we look at the climate variation that were cause by the eruption of the Eldgjá volcano, we can see that the way it impacted climate change was by cooling the surface of the planet Earth.
While the Eldgjá volcano eruption caused the Earth’s temperature to cool down, it also cleared the path for another volcanic eruption that would the Laki volcano eruption. Similarly, to the Eldgjá eruption that happened in Iceland, the Laki volcano eruption was also situated in Iceland. The Laki eruption volcanic eruption mainly happened from the year 1783 to the year 1784.
Another volcanic eruption that the Eldgjá eruption would have links to would be the eruption of the Changbaishan volcano. The Changbaishan eruption happened at the end of the year 946 CE. This volcanic eruption would have also caused the Earth’s climate to cool down.
3d- Aptian giant explosive eruptions
Another area on Earth where volcanic eruptions had links to climate change would be the Songliao Basin in Northeast Asia (more precisely Northeast China). A significant event that was of interest to some researchers in that area were Aptian giant explosive eruptions that happened approximately 121 million years ago until 109 million years ago. The volcanic eruptions that occurred from these events caused major cooling that affected the surface of our planet.
According to researchers, the complete area that covers the volcanic eruptions known as the Aptian giant explosive eruptions can be divided into seven smaller areas that are characterized by unique stratigraphic successions.
The result of these volcanic eruptions would have left randomly deposited volcanic ash that would have impacted the marine deposits because the volcanic ash deposited in them was irregular. If we now look at the Aptian giant explosive eruptions and their links to climate change, it is possible to see that these eruptions could be characterized as "volatile-rich Plinian and phreatomagmatic eruptions" (Wang et al., 2015, p. 104).
During the said eruptions, an important quantity of ash and of gases was thrown into the atmosphere. Most of the gases that were ejected by these volcanic eruptions were aerosols and greenhouse gasses. One of the main types of gas that researchers have found to be part of the aerosols of these volcanic eruptions was hydrogen sulfide.
The link that the Aptian giant explosive eruptions would have with climate change would be that the volcanic dust emissions ended up in the stratosphere. Because of this, researchers think that some of the volcanic eruptions that were part of the Aptian giant explosive eruptions would have caused "changes in solar radiation and global circulation patterns of climate, and modifications of the global carbon cycle […]" (Wang et al., 2015, p. 104). These changes caused what is known as the early Aptian global climate change.
4- Conclusion
In this paper we presented the fact that volcanic eruptions, all along the Earth’s history, played an important role on the impact of climate change. To prove our point, in the first part of our essay, we looked at some of these impacts by looking at the volcano-climate forcing, the potential for volcanic response to climate change, evidence of climate response. In the second part of this essay, we looked at the impacts of volcanism on climate change in more details. This section started by looking at the bipolar correlation of volcanism with millennial climate change then it looked at the climate responses to large high-latitude and low-latitude volcanic eruptions, synchronous volcanic eruptions and abrupt climate change that may be linked by the stratospheric ozone depletion and finally this section looked at how a volcanic gas (sulfur dioxide) impacts climate change. In the third section, this essay looked at different areas that had important volcanic activities over time, specific eruptions as well as major time periods such as the Little Ice Age and the Cenozoic period.
References
Bay, R., Bramall, N., & Price, P. (2004). Bipolar Correlation of Volcanism with Millennial
Climate Change. Proceedings of the National Academy of Sciences of the United States of America, 101(17), 6341-6345. http://www.jstor.org/stable/3372084
Cooper, C. L., Swindles, G. T., Savov, I. P., Schmidt, A., & Bacon, K. L. (2018). Evaluating the
relationship between climate change and volcanism. Earth-Science Reviews, 177, 238-247. https://doi.org/10.1016/j.earscirev.2017.11.009
Kashiwagi, H., & Shikazono, N. (2003). Climate change during Cenozoic inferred from global
carbon cycle model including igneous and hydrothermal activities,
Palaeogeography, Palaeoclimatology, Palaeoecology, 199 (3–4), 167-185.
https://doi.org/10.1016/S0031-0182(03)00506-6
Lanciki, A., Cole‐Dai, J., Thiemens, M. H., and Savarino, J. (2012), Sulfur isotope evidence of
little or no stratospheric impact by the 1783 Laki volcanic eruption, Geophys. Res. Lett.,
(39), L01806, doi:10.1029/2011GL050075
McConnell, J. R., Burke, A., Dunbar, N. W., Köhler, P., Thomas, J. L., Arienzo, M. M.,
Chellman, N. J., Maselli, O. J., Sigl, M., Adkins, J. F., Baggenstos, D., Burkhart, J. F.,
Brook, E. J., Buizert, C., Cole-Dai, J., Fudge, T. J., Knorr, G., Hans-F. Graf, H.-F.,
Grieman, M. M., … Winckler, G. (2017). Synchronous Volcanic Eruptions and Abrupt
Climate Change ∼17.7 Ka Plausibly Linked by Stratospheric Ozone Depletion.
Proceedings of the National Academy of Sciences of the United States of America 114,
(38), 10035-0040. https://www.jstor.org/stable/26487935
Miller, G. H., Geirsdóttir, Á., Zhong, Y., Larsen, D. J., Otto‐Bliesner, B. L., Holland, M. M.,
Bailey, D. A., Refsnider, K. A., Lehman, S. J., Southon, J. R., Anderson, C., Björnsson, H., & Thordason, T. (2012). Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea‐ice/ocean feedbacks, Geophys. Res. Lett., 39, L02708, doi:10.1029/2011GL050168
Oppenheimer, C., Orchard, A., Stoffel, M., Newfield, T. P., Guillet, S., Corona, C., Sigl,
M., Di Cosmo, N., & Büntgen, U. (2018) The Eldgjá eruption: timing, long-range
impacts and influence on the Christianisation of Iceland. Climatic Change 147, 369–381.
https://doi.org/10.1007/s10584-018-2171-9
Schneider, D. P., Ammann, C. M., Otto‐Bliesner, B. L., & Kaufman, D. S. (2009), Climate
response to large, high‐latitude and low‐latitude volcanic eruptions in the Community Climate System Model, J. Geophys. Res., 114, D15101, doi:10.1029/2008JD011222
Wang, P., Chen, C., & Liu, H. (2016). Aptian giant explosive volcanic eruptions in the Songliao
Basin and northeast Asia: A possible cause for global climate change and OAE-1a, Cretaceous Research, 62, 98-108. https://doi.org/10.1016/j.cretres.2015.09.021
Ward, P. L. (2009). Sulfur dioxide initiates global climate change in four ways,
Sulfur dioxide initiates global climate change in four ways, Thin Solid Films, 517 (11),
3188-3203. https://doi.org/10.1016/j.tsf.2009.01.005
Comments
Post a Comment