At the time of this writing, news outlets are reporting of the deadly tsunami, or tidal wave, that was triggered by the collapse of the Krakatoa volcano in Indonesia. While a tsunami is not itself a meteorological event (and can be discussed in more detail in a later post), the National Weather Service does have two branches, the National Tsunami Warning Center and the Pacific Tsunami Warning Center, which are responsible for monitoring the oceans for conditions which may trigger a tsunami.
In any given year, there can be upwards of 50 active volcanoes around the world. These eruptions can be large and violent, or rather small and insignificant. Many of the eruptions, although not all, occur in the region known as the ‘Ring of Fire’; the area surrounding the Pacific Ocean where active plate tectonics causes numerous earthquakes and volcanic activity.
One might ask the question, “Can an erupting volcano affect the weather?” The answer is YES, depending on the magnitude of the eruption. While the Krakatoa volcano is in the news at the moment because there was a tsunami which resulted in numerous fatalities, Sicily’s Mount Etna was also active during the last week of 2018 . While it is not creating widespread impacts on the weather, ash and smoke are affecting the air quality at many surrounding villages and also creating travel headaches at Catania Airport, which is located south of the mountain on Sicily’s east coast.
During April and May of 2010, volcanoes in Iceland spewed ash and smoke into the atmosphere, which was then carried across Europe on the jet stream winds and wreaked havoc on air traffic for weeks. Volcanic ash can pose an imminent danger to aircraft engines, and thus many airports across Europe were forced to close, stranding travelers for days. The widespread disruption to air traffic was the largest since World War II (http://news.bbc.co.uk/2/hi/science/nature/8621992.stm).
The volcanic eruption in recent memory which had the largest impact on worldwide weather was Mt. Pinatubo in 1991. The eruption on June 15, 1991 was the second largest eruption in the 20th century and caused earthquakes, lava flows, and spewed ash and smoke far into the atmosphere (https://pubs.usgs.gov/fs/1997/fs113-97/).
Similar to the massive Krakatoa eruption of 1883, volcanic ash high in the atmosphere was transported around the Northern Hemisphere after Mt. Pinatubo erupted and resulted in a measurable cooling effect during the year that followed. While the global cooling which occurred as a result of the Pinatubo eruption was not as marked as that which followed the 1883 eruption of Krakatoa (1884 was colloquially known as ‘the year without a summer’), there was an observed cooling in the Northern Hemisphere of approximately 0.5 degrees Celsius during 1992, the year which followed Pinatubo. While this may not sound like much, the prevailing weather patterns during the summer of 1992 were characterized by cooler than normal temperatures across the United States and elsewhere in the Northern Hemisphere. Further, chemicals thrown into the atmosphere by the volcano resulted in spectacular sunsets all across the Northern Hemisphere. The cooling effect of Mt. Pinatubo temporarily took the spotlight off of the warming temperature trend around the globe that was being observed and studied during the 1980s and 1990s as scientists were beginning to understand the relationship between fossil fuel burning and emissions and Earth’s warming climate.
So, the answer is ‘YES’! Volcanoes can and do affect the weather. Generally the effects are localized and characterized by decreases in air quality due to ash, chemicals and smoke emitted by the volcano, but larger volcanic eruptions can impact weather conditions around the globe for months to years!