deforestation, which is an
example of humans impacting their environment and those environmental
impacts turning around and impacting human events.
Second, it will discuss the eruption of the Laki volcano in 1783-1784
and its effect on historical events in both Iceland and the rest of the
Deforestation has had a large impact on the course of human history in Iceland because of the environmental impacts of deforestation. Deforestation has dramatic effects on soil quality, as trees are needed to hold soil together, which creates a stable basis for building as well as protects land from erosion and flooding. Forests also hold nutrients in the soil, so less forested land mean less arable land. Moreover, forests are important for the winter grazing of sheep, so less forested land means less ability to feed sheep. It is likely that deforestation (in addition to changing climate in the little ice age and the periodic eruption of volcanoes) constrained Iceland’s population, which remained more or less unchanged for the first thousand years of Iceland’s history.
Iceland has since recognized the need for conservation of its forests, first passing legislation to conserve and replenish forests at the end of the 19th century in the wake of massive sandstorms near the capital city of Reykjavik. These sandstorms were caused by the degredation of soil associated with deforestation. Despite almost a century of efforts, more than 1/3 of Iceland is still considered a desert today and no more than 1 percent of the country is forested.
In Iceland, the volcanic eruption had two main effects. First, the volcano destroyed agricultural land. About 565 km2 of land were covered by lava extrusion at a depth of about 20 m. Second, sulfur dioxide released from the volcano resulted in a haze of sulfuric air, which enveloped the island. According to the Agency for Toxic Substances and Disease Registry, sulfuric dioxide can cause significant respiratory problems in humans and animals as well as significant irritation and even burns of eyes and skin and gastrointestinal problems. As a result, 80 percent of Iceland’s sheep, 75 percent of its horses, and 50 percent of its cattle died. 13,000 Icelanders died of famine and disease, or about 1/5 of the population.
In terms of global effects, Laki immediately affected plants, animals and humans in continental Europe and points further east. This is partly because the prevailing winds at these latitudes are westerlies, which drove the sulfuric haze away from Iceland and towards Europe. Sulfuric dioxide also interacts with atmospheric water to form sulfuric acid, which results in acid rain, which we know destroys vegetation. As a result, places like Prague, Munich and even Japan experienced famine.
Moreover, Laki’s eruption altered the global climate for several years. Laki’s eruption was exceptional for the sheer volume of sulfur dioxide it produced (122 megatons) and because its eruption column was so high, extending from 9 to 14 kilometers into the air. This meant that up to 95 megatons of sulfur dioxide reached the upper levels of the troposphere and lower levels of the stratosphere. Because of Laki’s location, this sulfur dioxide entered the polar jet stream and quickly spread around the world. The overall climatic effect of Laki was a decrease in global temperatures of around 1.5 degrees Celsius (as measured in North America and Europe) because of an increased albedo in Earth’s atmosphere. This made 1783, 1784, and 1786 the coldest winters on record in the eighteenth century and led to a cascade of environmental effects, ranging from ice forming on the Mississippi River near New Orleans to the worst famines on record in Japan.
Harris, Richard. “Viking Farms Tell Cautionary Climate Tale,” NPR, Dec. 3, 2007. Accessed Nov. 12, 2017. <https://www.npr.org/templates/story/story.php?storyId=16835101>
Fountain, Henry. “Vikings Razed the Forests. Can Iceland Regrow Them?” The New York Times, Oct. 20, 2017. Accessed Nov. 12, 2017. <https://www.nytimes.com/interactive/2017/10/20/climate/iceland-trees-reforestation.html?_r=0>
Mikhail, Alan. “Ottoman Iceland: A Climate History.” Environmental History, Vol. 20 Issue 2, Apr. 1, 2015, pages 262 – 284. Accessed Nov. 12, 2017. <https://academic.oup.com/envhis/article-lookup/doi/10.1093/envhis/emv006>
“Toxic Substace Portal – Sulfur Dioxide.” Agency for Toxic Substances and Disease Registry. Accessed Nov. 12, 2017. <https://www.atsdr.cdc.gov/mmg/mmg.asp?id=249&tid=46>
By: Riley Collins