Global Warming and Volcanism
Tuesday, 15. April 2008, 14:37:53
Much has been written about the impact from volcanic eruptions on climate change (cooling) and sea level changes. Less has been said about the impact from global warming and sea level rise on volcanism.
Sea level rise can reactivate volcanoes situated near sea level. Alaska's Pavlof volcano erupts every winter when (local) sea levels are higher - well just about 30 centimetres. Thirteen of sixteen magmatic eruptions of Pavlof Volcano in nine of the years from 1973 to 1998 have occurred between 9 September and 29 December. A significant correlation exists between the eruptions and yearly nontidal variations in sea level and may result from ocean loading. (See this abstract). The melting of polar ice sheets from global warming and the resulting stress placed on the earth's crust from rising sea levels will cause more magma and increase volcanic eruptions on a global scale in the years to come.
Carolina Pagli of the University of Leeds, UK, and Freysteinn Sigmundsson of the University of Iceland in Reykjavik calculated how shrinkage of the Icelandic ice cap Vatnajökull affects what is happening below ground. Their findings will shortly be published in Geophysical Research Letters.
Pagli, C., and F. Sigmundsson (2008), Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajokull ice cap, Iceland, Geophys. Res. Lett., doi:10.1029/2008GL033510, in press.
When ice disappears, the added weight it forced upon the crust below it disappears as well. As a result this is increasing the rate at which the rocks under the ice sheet melt into magma. Iceland is home to several active volcanoes that exist underneath the ice, including Gjàlp, home of the last big eruption in 1996, and 58 years earlier in 1938. But according to Pagli and Sigmundsson the extra magma produced over the past century and more could reduce that time down to a gap of 30 years between each eruption. Volcanoes in Antarctica and Alaska will be at risk of similar increased volcanic activity. The shifting stresses could even cause eruptions in unexpected places.
And now that I am talking about Icelandic volcanoes - according to Iceland Review Online a giant volcano has recently been discovered off Reykjanes peninsula, Southwest Iceland, almost as large as the peninsula itself, and expected to erupt at any time. In the centre of the volcano there is a caldera measuring ten kilometres in diameter.
Since the volcano is at a depth of 1,500 metres eruptions would not have any effect on Iceland, except perhaps causing earthquakes (and tsunamis?). The volcano’s discovery is considered significant because it was believed it couldn’t exist in that area. Such large volcanoes are not supposed to be located on oceanic ridges. They are always drifting apart and that prevents a volcano from being created, so the volcano’s existence really came as a surprise.
• http://www.dailygalaxy.com/my_weblog/2008/04/will-a-warmer-w.html#more
• http://environment.newscientist.com/channel/earth/mg19826515.100-melting-ice-caps-may-trigger-more-volcanic-eruptions.html
• http://www.abc.net.au/news/stories/2007/09/14/2033161.htm?section=justin
• http://environment.newscientist.com/channel/earth/climate-change/mg19626324.600-volcanoes-give-sea-level-a-temporary-boost.html
• http://www.abc.net.au/science/news/stories/2005/1494475.htm
Sea level rise can reactivate volcanoes situated near sea level. Alaska's Pavlof volcano erupts every winter when (local) sea levels are higher - well just about 30 centimetres. Thirteen of sixteen magmatic eruptions of Pavlof Volcano in nine of the years from 1973 to 1998 have occurred between 9 September and 29 December. A significant correlation exists between the eruptions and yearly nontidal variations in sea level and may result from ocean loading. (See this abstract). The melting of polar ice sheets from global warming and the resulting stress placed on the earth's crust from rising sea levels will cause more magma and increase volcanic eruptions on a global scale in the years to come.
Carolina Pagli of the University of Leeds, UK, and Freysteinn Sigmundsson of the University of Iceland in Reykjavik calculated how shrinkage of the Icelandic ice cap Vatnajökull affects what is happening below ground. Their findings will shortly be published in Geophysical Research Letters.
Pagli, C., and F. Sigmundsson (2008), Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajokull ice cap, Iceland, Geophys. Res. Lett., doi:10.1029/2008GL033510, in press.
When ice disappears, the added weight it forced upon the crust below it disappears as well. As a result this is increasing the rate at which the rocks under the ice sheet melt into magma. Iceland is home to several active volcanoes that exist underneath the ice, including Gjàlp, home of the last big eruption in 1996, and 58 years earlier in 1938. But according to Pagli and Sigmundsson the extra magma produced over the past century and more could reduce that time down to a gap of 30 years between each eruption. Volcanoes in Antarctica and Alaska will be at risk of similar increased volcanic activity. The shifting stresses could even cause eruptions in unexpected places.
And now that I am talking about Icelandic volcanoes - according to Iceland Review Online a giant volcano has recently been discovered off Reykjanes peninsula, Southwest Iceland, almost as large as the peninsula itself, and expected to erupt at any time. In the centre of the volcano there is a caldera measuring ten kilometres in diameter.
Since the volcano is at a depth of 1,500 metres eruptions would not have any effect on Iceland, except perhaps causing earthquakes (and tsunamis?). The volcano’s discovery is considered significant because it was believed it couldn’t exist in that area. Such large volcanoes are not supposed to be located on oceanic ridges. They are always drifting apart and that prevents a volcano from being created, so the volcano’s existence really came as a surprise.
• http://www.dailygalaxy.com/my_weblog/2008/04/will-a-warmer-w.html#more
• http://environment.newscientist.com/channel/earth/mg19826515.100-melting-ice-caps-may-trigger-more-volcanic-eruptions.html
• http://www.abc.net.au/news/stories/2007/09/14/2033161.htm?section=justin
• http://environment.newscientist.com/channel/earth/climate-change/mg19626324.600-volcanoes-give-sea-level-a-temporary-boost.html
• http://www.abc.net.au/science/news/stories/2005/1494475.htm
WIDGETIZE
jmgarneau # 4. May 2008, 03:34
I would like to learn if there has been any data or research on historical correlation between increased sea level and increased volcanic activity. To further those thoughts and ask if there is an increase in volcanic activity would it trigger a cooling effect on the planet and start to reverse the process of the melting ice caps?? Any thoughts?
Ole Nielsen # 5. May 2008, 18:59
There are plenty of documented cooling effects from large volcanic eruptions (generally speaking), but these effects are usually short termed (from one up to a few years) - when we talk climate change.
Periods of large scale volcanic eruptions of flood basalt in large igneous provinces going on for extremely long periods (thousands or maybe even up to a few million years) are of course different. Here I think of the Deccan Traps, the Siberian traps etc.
Ole