After a cooler than normal summer, the Climate Prediction Center's most recent seasonal forecast shows that the east coast, including North Carolina has better than normal chances for a warmer than normal autumn. As much variability as there is in long-range forecasts, there is a potential threat to its accuracy that the climate models used don't even consider: a major volcanic eruption.
Currently, there are 147 active volcanoes around the world with activity ranging from "unrest" to currently erupting. The one that is garnering the most attention in the northern hemisphere is Iceland's Bardarbunga Volcano, which lies under a glacier near the center of that country. Earthquake activity has increased dramatically in recent days with a 5.7 magnitude quake occurring on Tuesday. Wednesday night scientists who are watching and evaluating the volcano noticed fissures and cauldrons forming in the ice, showing that activity below the ice is increasingly heating the glacier.
In the recent past, major eruptions have caused evacuations and interrupted regional air travel. In the distant past, volcanic eruptions have plunged the world into cooler than normal temperatures for months to years at a time. Stories have been recorded about years "without a summer" including one that effected North Carolina almost two hundred years ago in 1816.
Volcanic ash can rise high into the atmosphere, get caught up in the jet stream, and disperse in such a way that it basically blocks the sun's radiation - not completely, but enough to lower temperatures quite a bit. One of the anomalous effects recorded in North Carolina in 1816 after Mount Tambora's eruption, we heavy frost across the state on August 22nd. Can you imagine waking up to frost in the summer?
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While it's possible that the Bardarbunga Volcano's next eruption may be relatively minor, expectations seem to be increasingly tending toward a massive eruption that could play a role in how our fall and winter turn out here at home.