While the very visible ash exploding out of the erupting La Soufriere Volcano on St. Vincent in the Caribbean has led to countless heartbreaking photographs and videos shared online, satellites are tracking another hazard from the volcano as a potentially toxic plume rises from it and wraps around the Earth. Based on data captured by the Sentinel-5 Earth-observing satellite, the toxic plume of sulfur dioxide has made it all the way to India as of yesterday.
The ADAM Platform has been sharing images reflecting the volume of sulfur dioxide (SO2) leaving the Caribbean volcano as it spreads over northern South America, the Atlantic Ocean, Africa, and now Asia. Imagery shared yesterday shows a narrow band of concentrated SO2 emissions reaching as far away as India. The ADAM Platform is using data from the Sentinel 5-Precursor satellite, also known as Sentinel 5P, which was launched into space by the European Space Agency (ESA) in October 2017. As part of the European Commission’s Copernicus program, the Sentinel 5P was the first in the series dedicated to monitoring the Earth’s atmosphere. Using the state-of-the-art Tropomi instrument, it is able to collect data on a variety of gases in the atmosphere such as nitrogen dioxide, ozone, formaldehyde, sulfur dioxide, methane, carbon monoxide, and various aerosols.
Sulfur dioxide affects human health when it is breathed in. It irritates the nose, throat, and airways to cause coughing, wheezing, shortness of breath, or a tight feeling around the chest. The effects of sulfur dioxide are felt very quickly and most people would feel the worst symptoms in 10 or 15 minutes after breathing it in. Those most at risk of developing problems if they are exposed to sulfur dioxide are people with asthma or similar conditions. Extreme concentrations of sulfur dioxide can be deadly if inhaled. When combined with other substances additional hazards can be created; as an example, rain falling through a sulfur dioxide plume could produce an acid rainfall. Sulfur dioxide is invisible to the human eye, but when it reacts with other gases, aerosol particles can form to cause haze, and according to NASA in extreme widespread events, climate cooling.
During the May 2018 eruption of Hawaii’s Kilauea Volcano’s Lower East Rift Zone, sulfur dioxide was covering the surface in a residential neighborhood from erupting fissures. During that eruption, a plume of sulfur dioxide was detected by the Ozone Mapper Profiler Suite (OMPS) on the Suomi-NPP satellite. During the height of that eruption during the spring and summer of 2018, authorities evacuated people from the danger sulfur dioxide posed. “Hawaii Fire Department reports extremely dangerous conditions due to high levels of Sulfur Dioxide gas in the evacuation area. Elderly, young, and people with compromised respiratory systems are especially vulnerable,” warned the Hawaii County Civil Defense in 2018. They added, “The high levels detected are an immediate threat to life for all who become exposed. First responders may not be able to come to the aid of residents who refuse to evacuate. ”
According to the University of the West Indies Seismic Research Centre and their latest scientific update issued earlier today, the first successful measurements of sulfur dioxide (SO2) flux were taken along the west coast of St. Vincent and yielded an average SO2 flux of 809 tons per day. “Flux is the measurement of mass of SO2 in the plume, a stream of gas vented by the volcano,” the Seismic Research Centre wrote. They added, “The presence of SO2 tells us that fresh magma from a deeper (location) is being degassed indicating that the eruption is continuing.”
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While harmful gas can be an issue near the active vents, as was the case with Kilauea’s 2018 eruption, the gas can also rise high and spread far from the eruption, as is the case now with La Soufriere. Large quantities of SO2 in the atmosphere can have significant implications to global climate.
In the journal “Thin Solid Films”, Peter Ward published a report in 2019on how sulfur dioxide initiates global climate change in 4 ways. “All major historic volcanic eruptions have formed sulfuric acid aerosols in the lower stratosphere that cooled the earth’s surface ~ 0.5 °C for typically three years. While such events are currently happening once every 80 years, there are times in geologic history when they occurred every few to a dozen years. These were times when the earth was cooled incrementally into major ice ages. There have also been two dozen times during the past 46,000 years when major volcanic eruptions occurred every year or two or even several times per year for decades. Each of these times was contemporaneous with very rapid global warming.”
According to Ward, when major volcanic eruptions do not occur for decades to hundreds of years, the atmosphere can oxidize all pollutants, leading to a very thin atmosphere, global cooling and significant, long-term drought. Prior to the 20th century, increases in atmospheric carbon dioxide followed increases in temperature initiated by changes in sulfur dioxide. But since the 20th century, the atmosphere has become rich with other greenhouse gasses due to the industrial revolution.
It is too soon to determine what impacts this plume of SO2 will have on global climate and whether any significant cooling or even warming could occur.
On June 15, 1991, Mount Pinatubo had a massive eruption that lasted 9 hours; using satellite data of that event, scientists estimated that the total sulfur dioxide released into the atmosphere was roughly 15-20 million tons. Because that single eruption occurred with a tremendous amount of force, ash and gas was ejected high into the stratosphere. Strong stratospheric winds spread the sulfur dioxide and its related aerosol particles around the globe over a two year period. Based on analysis of that volcanic eruption and global temperatures, NASA believes there was a global drop in temperature of about 1 degree F / 0.6 degrees C. Because the stratosphere is above the troposphere where weather occurs, rain wasn’t able to “wash-out” the SO2 from the eruption as efficiently as it would in the troposphere, leading to more significant climate impacts.
Beyond the impacts to St. Vincent and nearby islands from gas and ash, scientists around the globe will help determine what, if any, the global impacts from this Caribbean eruption could be. While the 809 tons/day of SO2 currently coming from La Soufriere pales in comparison to the 15-20 million tons ejected from Mount Pinatubo, La Soufriere continues to erupt with somewhat regular explosive eruptions. Exactly how much gas is released and where in the atmosphere it is inserted will be key to determining what long range impacts this single volcano will have around the Earth.