Yellowstone Super Volcano Eruption Affect on Weather

978ff92161656cbd491edd3b370b04f6 — A geothermal pool at the Wyoming park. Photo: AFP

Most people have heard of the caldera “Super Volcano” sitting under Yellowstone National Park. While the threat of an eruption in the near future is unlikely, what would happen if it did erupt? In this excerpt from a Discovery News article, the U.S Geological Survey (USGS) scientists share their thoughts:

“The scientists at the U.S. Geological Survey’s Yellowstone Volcano Observatory reassure that there isn’t anything unusual going on under the park, and that the odds are that it won’t erupt for centuries. But when the volcano eventually does blow, they say, it’s going to be a gigantic event that will spew enough ash to blanket the Rocky Mountains with a layer that could be several feet thick, and send particles across the entire country, with some even reaching far-away cities such as New York and Washington, D.C.”

This graphic from the USGS shows volcanic ash would travel all the way to the Atlantic Ocean. Approximately 3 – 10 mm of ash would fall in Kentucky!

img20140831101153624755021 (1) — U.S Geological Survey Volcanic Ash Map

But how would the eruption of this Super Volcano affect our weather? Weather Underground explains the various affects:

“A likely location for the next mega-colossal eruption would be at the Yellowstone Caldera in Wyoming, which has had magnitude 7 or 8 eruptions as often as every 650,000 years. The last mega-colossal eruption there was about 640,000 years ago.”

“If a mega-colossal eruption were to occur today, it would probably not be able to push Earth into an ice age, according to a modeling study done by Jones et al. (2005). They found that an eruption like Toba would cool the Earth by about 17°F (9.4°C) after the first year (Figure 3), and the temperature would gradually recover to 3°F (1.8°C) below normal ten years after the eruption. They found that the eruption would reduce rainfall by 50% globally for the first two years, and up to 90% over the Amazon, Southeast Asia, and central Africa. This would obviously be very bad for human civilization, with the cold and lack of sunshine causing widespread crop failures and starvation of millions of people. Furthermore, the eruption would lead to a partial loss of Earth’s protective ozone layer, allowing highly damaging levels of ultraviolet light to penetrate to the surface.”

Annual near-surface temperature anomalies for the year following a mega-colossal volcanic eruption like the Toba eruption of 74,000 years ago, if it were to occur today. Most land areas cool by 22°F (12°C) compared to average. Some areas, like Africa, cool by 29°F (16°C). Image credit: Jones, G.S., et al., 2005, "An AOGCM simulation of the climate response to a volcanic super-eruption", Climate Dynamics, 25, Numbers 7-8, pp 725-738, December, 2005. — Annual near-surface temperature anomalies for the year following a mega-colossal volcanic eruption like the Toba eruption of 74,000 years ago, if it were to occur today. Most land areas cool by 22°F (12°C) compared to average. Some areas, like Africa, cool by 29°F (16°C). Image credit: Jones, G.S., et al., 2005, “An AOGCM simulation of the climate response to a volcanic super-eruption”, Climate Dynamics, 25, Numbers 7-8, pp 725-738, December, 2005.

However, this would not be enough to reverse global warming! Another comment from the same article mentions volcanoes actual warm the climate in the long run.

“While volcanoes cool the climate on time scales of 1 – 2 years, they act to warm the climate over longer time scales, since they are an important source of natural CO2 to the atmosphere.”

So if the Yellowstone Super Volcano were to erupt, we would see much colder than average temperatures across the United States for the first several years.