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Laki, Iceland 1783

Laki,Iceland 1783

Laki,Iceland 1783

Althoughenvironmental pollution is perceived to be more significant in themodern world, it has been taking place for many centuries. However,most of the environmental issues that are being experienced atpresent result from human activities, unlike the ancientenvironmental pollution that was mainly caused by naturaloccurrences. For example, volcanic eruptions have historicallydamaged the environment and caused serious damages to thebiodiversity. According to Grattan, Rabartin, Self &amp Thordarson(2002) the environmental impact of volcanic eruption depend on themodification it causes to climatic conditions through emission ofvolcanic gases (such as H2SO4) and other products. Environmentalimpacts caused by human activities are gradual, but the effect ofnatural calamities, especially volcanic eruption causes devastatingdamage within a short period of time. The present study will addressthe impact that resulted from the Laki volcanic eruption in 1783 withthe main focus on its impact on the atmosphere and the environment.

Background

TheLaki volcanic eruption that occurred in Iceland in 1783 is one of thelargest eruptions to be recorded in the world’s history. Theeruption did not occur as a single event, but as a continuousexplosion and flow of lava that took approximately eight months(Thordarson &amp Self, 2003). The Laki eruption was characterized bythe emission of magma and different types of gases into theatmosphere, which was the major cause of the dry fog in the region?It is estimated that the Laki eruption emitted sulfur dioxides gasamounting to 122 Tg, which combined with the atmospheric moisture toform aerosols of sulfuric acid amounting to about 180 Tg (Grattan,Rabartin, Self &amp Thordarson, 2002). In addition, the Lakieruption created a basaltic magma of 15 cubic kilometers along the 27kilometers of the Laki fissure, which streamed for a period of eightmonths. The flowing lava covered a region of about 565 km 2producing a large number of tuff and scoria cones along the Lakifissures as shown in Figure 1.

Figure1: Tuff and scoria cones along the Laki fissures

Source:Young (2011)

TheLaki eruption had both local and global effects because part of theaerosol was discharged to distant lands while some of it was affectedthe local land. According to Klemetti (2013) 80 % of the aerosol wasexploded to a distance of about 10 km above the vent and dominatedthe tropopause level of the atmosphere in Iceland before spreadingand landing in distant regions of Europe as shown in Figure 2. Theremaining 20 % of the aerosol was produced by the cooling lava andproduced the haze that lasted for a period close to the local ground.Although the Laki eruption lasted for a period of eight months, it isestimated that about 90 % of the total lava flows was ejected duringthe first five months (Klemetti, 2013). This means that the series ofthe Laki eruption occurred at a reducing rate during the last threemonths.

Figure2: Dispersal of plumes from Laki eruption

Source:Klemetti (2013)

Environmentaleffects of Laki eruption

Thefallout of fine ash and volcanic haze resulted in severeenvironmental effects in Iceland, which in turn affected thebiodiversity, including animals, vegetation, and people. The plumesejected in the initial phases of Laki eruption contained gases andash that affected regions that are close to Laki. Most of the gasesreleased by the volcano reacted with the atmospheric moisture toacidic rain (Thordarson &amp Self, 2003). The falling acid raincaused wounds on the skin of human beings and animals and burning ofholes in the leaves of the dock. The high acid content also causedirritation of eyes among the inhabitants of Iceland. In addition, thefall of white dust containing sulfuric acid, black ash, and acid rainwas indicated by stained metal objects in Iceland regions that areclose to Laki. The destruction of trees, mosses, shrubs, and otherforms of vegetation cover was among the devastating environmentaldestruction that was mainly caused by the acid rain and the flow ofmagma. According to Thordarson &amp Self (2003) most of the plantsthat were destroyed in Iceland disappeared for 3-10 years in someregions and never returned in some areas.

Effectsof Laki eruption on human health

Lakieruption had both direct and indirect effects on human health. Thevolcano killed about 10,000 people of Iceland, which was about 20 %of the total population of the young country (Castella, 2010). Apartfrom the death of people, the eruption emitted various compounds thatcaused illnesses to the population that survived the calamity. Forexample, the widespread of chronic fluorosis was reported in manyparts of the country between the late summer and early part of thewinter that followed the period of Laki eruption. Chronic fluorosiscaused dental lesions, an outgrowth of spikes on molars, anddeformation and softening of bones. This type of illness caused massdeaths in southeast regions of the Iceland that were covered withfine ash. The Laki eruption caused severe hunger, which was caused bytwo factors for a period of about three years. First, the destructionof vegetation, which was part of the environmental pollution,resulted in death of about 60 % of livestock. Secondly, the fall ofacid rain, fine as, and the flow of magma polluted and destroyedagricultural land, thus reducing its productivity along the Sidahighland, Landbrot, and Medalland as shown in Figure 3. The entirepopulation of Iceland was rural at the time of Laki eruption, whichmeans that they relied on fishing and agriculture for theirlivelihood. Death, sicknesses, and famine lasted for several yearsafter the occurrence of the Laki eruption, which made Iceland as oneof the most difficult places for human survival for some years afterthe eruption.

Figure3: Regions affected by magma

Source:Klemetti (2013)

Althoughthe actual eruption occurred in Iceland, different components(including gases and ash) caused environmental and adverse healtheffects in other parts of the world, especially in Europe. Some ofthe distant plumes that were ejected at a distance of about 10 kmabove the vents landed in Europe, where it caused severe atmosphericand environmental damage. It was reported that the northern and theWestern Europe experienced periods of the deposition of dry and wetvapors of sulfuric acid, which flooded these regions with severesulfurous odor (Thordarson &amp Self, 2003). Although acid rain wasnot reported in many parts of Europe, the fall of fine ash and sulfurvapor caused the weathering of vegetation that resulted in thedestruction of vegetation, including the corn plantations. Trees losttheir color and some died, which was an occurrence that resulted inthe loss of large areas of forest cover. Laki eruption haddisproportionate environmental and health effects where areas closeto the point of eruption were affected more than areas that were faraway.

Climaticeffects of Laki eruption

TheLaki volcanic eruption released toxic compounds into the loweratmosphere and the upper atmosphere, which is the major cause ofunique climatic conditions experienced in the region. The short-livedclimatic effects were associated with the release of mass-independentisotopes (such as SO4) (Schmidt, Thordarson, Oman &amp Robock,2012). Although volcanic eruptions emit a combination of differenttypes of gas, sulfur dioxide (SO2) is the major cause of climateanomalies. The atmospheric aerosols produced during volcanic eruptionresults in short-term and long-term effects on climate in three ways.First, SO2 form atmospheric aerosols that have the capacity toreflect solar radiation and return it back to the space, anoccurrence that produces a negative radiation forcing (Highwood &ampStevenson, 2003). Secondly, aerosols of SO2 can absorb solarradiation, thus heating the atmosphere. Third, aerosols act likegreenhouse gases, which prevent radiations from reaching the spacefrom the ground. This type of long wave radiative forcing becomeslarge when aerosol emission occurs in the troposphere like in thecase of Laki eruption.

Short-termclimatic effect of Laki volcanic eruption

Theunusual heat wave that occurred in July of the aftermath of Lakieruption was caused by aerosols of different gases that were emittedinto the atmosphere. According to Thordarson &amp Self (2003) theheat wave occurred in the northern and Western Europe and it wascaused by the greenhouse effect of sulfur dioxide whose concentrationwas increased beyond the normal level in the lower atmosphere. Thisanomaly was strongest in the western part of Europe and declinedgradually with the increase in distance from Laki. However, theseanomalies in temperature were not experienced in August because ofunusual changes in the atmospheric circulation that occurred in July1783 over Europe. Persistent presence of anticyclones over Britainmaintained the flow of large masses of warm air over northern andWestern Europe.

Long-termeffects of Laki volcanic eruption on climate

Icelandrecorded the coldest seasons for a period of three years after theoccurrence of Laki eruption. The drop in the average annualtemperatures by 1.5 0C was consistent with the concentration of components of Laki haze(Thordarson &amp Self, 2003). This is because radiative thermalbalance was offset at higher latitudes of the northern hemisphere.Although large amounts of Laki haze had been removed from the Icelandand the European atmosphere by the onset of 1784 summer, theoccurrence of cold years in a back-to-back mechanism indicated acommon source of both the short-term and excursion of climate andLaki. In overall, both short-term and long-term climatic effects ofLaki resulted from the ejection of aerosols into the atmosphere,which altered the normal climatic conditions, especially thetemperature levels.

Conclusion

Lakiis among the largest volcanic eruptions recorded in the world’shistory. The occurrence of the Laki volcano as a series of eruptionsthat took place for a long duration (8 months) resulted indevastating effects that reshaped Iceland, which was a small countrywith a total population of 50,000 people. The devastating effects ofLaki eruption were mainly caused by ejection of aerosols of variousgases, especially the sulfur dioxide. The flow of magma only impactedthe local regions of Iceland there were close to Laki fissures. Theeffects of the Laki volcanic eruption are classified asenvironmental, climatic, and impacts on human health. Some of theseeffects lasted for the first few months while others remained foryears.

References

Castella,T. (2010, April 16). The eruption that changed Iceland forever. BBC.Retrieved April 17, 2014, from http://news.bbc.co.uk/2/hi/8624791.stm

Grattan,J., Rabartin, R., Self, S. &amp Thordarson, T. (2002). Volcanicair pollution and mortality in France 1783-1784.Abertystwyth, SY: The University of Wales.

Highwood,E. &amp Stevenson, D. (2003). Atmospheric impact of the 1783-1784Laki eruption: Part II climatic effects of sulphate aerosol. AtmosphericChemistry and Physics,3, 1177-1189.

Klemetti,E. (2013, July 6). Local and global impacts of the 1783-84 LakiEruption in Iceland. Eruptions.Retrieved April 17, 2014, fromhttp://www.wired.com/2013/06/local-and-global-impacts-1793-laki-eruption-iceland/

Schmidt,A., Thordarson, T., Oman, D. &amp Robock, A. (2012). Climatic impactof the long-lasting 1783 eruption: Inability of mass-independentsulfur isotopic composition measurements. Journalof Geophysical Research,117 (116), 1-10. doi: 10.1029/2012JD018414, 2012

Thordarson,T. &amp Self, S. (2003). Atmospheric and environmental effects ofthe 1783-1784 Laki eruption: A review and reassessment. Journalof Geophysical Research,108 (1), 1-29.

Young,J. (2011, May 28). Iceland’s Laki fissure eruption of 1783. DecodedScience.Retrieved April 17, 2014, fromhttp://www.decodedscience.com/icelands-laki-fissure-eruption-of-1783/932