Did a Volcanic Eruption Induce the Midwest 'Julytober'?

By Kristen Rodman, AccuWeather.com Staff Writer September 04, 2013; 6:57 AM

http://www.accuweather.com/en/weather-news/volcano-cooltemps-midwest/17180569

Throughout history, large volcanic eruptions have been known to influence climate.

This summer, the Midwest experienced a cold wave referred to as "Julytober" following the June eruption of Mount Sheveluch in Russia. Experts continue to compare this eruption to others from history and debate whether it could have induced the cooler Midwestern weather.

"Large Russian volcano eruptions tend to cool the Midwest," Historical Climatologist Evelyn Browning-Garriss said.

When a volcano erupts, if it is large enough, it can send debris miles into the stratosphere. The stratosphere is the atmosphere above where weather takes place.

Debris sent into the stratosphere by an eruption can include volcanic ash, chemicals and gases, specifically sulfur. This debris can influence temperatures by aiding in a decreased amount of solar radiation.

"Sulfur dioxide combines with water in the atmosphere to provide sulfuric acid aerosol droplets that reflect incoming solar radiation," PhD Research Geophysicist with the U.S. Geological Survey Alaska Volcano Observatory David Schneider said.

However, this is only the initial effect, the large effects of an eruption are not always immediate. Following an eruption, debris can build in the stratosphere over time and linger for years after.

"Large eruptions that inject several millions of tons of sulfur gases high into the atmosphere are known to change the weather," Academic Research Fellow at the Institute for Climate and Atmospheric Science at the University of Leeds Dr. Anja Schmidt said.

Sulfur dioxide gas can disrupt monsoons and cause winter warming of the Northern Hemisphere continents, according to Alan Robock, associate director for the Center of Environmental Prediction and distinguished professor with the Department of Environmental Sciences at Rutgers University.

The most recent example of this phenomena was exhibited by the eruption of Mount Pinatubo in the Philippines in 1991.

The eruption of Mount Pinatubo sent debris 15-20 miles high into the stratosphere, producing massive cloud coverage from the North Pole to 20 degrees south of the equator. As a result, the globe cooled by one half of one degree, according to Browning Garriss.

Although the eruption of Mount Sheveluch in June was minor compared to previous eruptions like Mount Pinatubo, two years before in 2011 there were two big eruptions in Russia and Iceland. These eruptions launched high amounts of debris into the air that still remain present today.

With a lot of debris already existent in the atmosphere, the addition of the debris from Mount Sheveluch may have then had the ability to possibly influence temperatures by blocking out sunlight, Browning-Garriss said.

While volcano experts agree that it is possible for an eruption to influence temperature, as observed in the historic "the year without a summer" in 1816 resulting from the disastrous 1815 eruption of Mount Tambora, most do not believe that the June Russian eruption was massive enough to impact temperatures.

"It is highly unlikely that the modest eruptions of Mount Sheveluch have contributed in a significant manner," Schneider said.

Regardless of the debated effects of Mount Sheveluch's eruption on Midwestern weather, the AccuWeather fall forecast predicts continued cool weather for the Midwest states into September.

An early frost or freeze is possible for the region as temperatures are expected to drop to the mid- to low 30s. Heading into late October and November, even colder weather is predicted, making an early snowfall possible for the area.