The Greenhouse Effect – US Department of State 1992
Image Credit: Environmental Protection Agency
Global warming is generally associated with the quantity of certain gases in Earth's atmosphere: most notably, carbon dioxide, methane, nitrous oxide and fluorinated hydrocarbons. Although some of these gases appear naturally, it is the introduction of an abnormal amount of them that concerns scientists and environmentalists.
Despite political controversy, there is valid reason to contemplate global warming. One possible manifestation of global warming is an increase in Earth’s seismic activity. There has been notable increase in the number as well as the violence of seismic activities during the last ten to twenty years.
Melting of glacial ice is one manifestation of global warming, and is of serious concern for the submarine fissures in Earth's crust. If methane clathrate (methane ice) filling these fissures melts from global warming, a very effective buffer system is compromised. Seismologists note that regions of the world where glacier density is largest exhibit the maximum frequency of ‘glacial quakes’—turbulent seismic conditions resulting in an increase of volcanic eruptions. Melting ice sheets results in a reduction of the forces exerted on Earth’s crust. This produces an "iso-static rebound" which jerks existing faults along the magma lines (connected to volcanoes), reactivating dormant volcanoes.
Suggestion — might the increasing number of retreating glaciers around the southern parts of Alaska increase the likelihood of earthquakes in parts of North America, with a similar occurrance at the other end of the globe?
With glaciers and ice-caps melting more quickly, water levels along coastal regions rises. As pieces break off, globally mass is redistributed. This affects gravitational forces, in turn stressing Earth’s crust, increasing seismic activity. Of special concern is the continental shelf around Greenland, says Worldwatch Institute. Underwater earthquakes could trigger massive landslides, generating massive tsunamis.
Evidence — there has been an unprecedented rise in the number of un-seasonal, unexplained tsunamis and regional earthquake activity, particularly along coastal regions. These seismic activities are not well-explained by survey data and statistics without the incorporation of global warming.
References and Resources
Worldwatch Institute: Global warming may trigger greater seismic activity
Harvard University Gazette: Global warming yields 'glacial earthquakes' in polar areas
University of California, Berkeley: The tectosphere and postglacial rebound