Greenhouse gas emissions from the eruptions are very small compared to those from fossil fuel burning
Two major volcanoes — Mauna Loa in Hawaii and Mount Semeru in Indonesia — erupted in a span of a week. Is it a sign of something bigger? What does it mean for the planet?
About 250 million years ago, the Siberian Traps — remnants of widespread volcanic activity — might have triggered the ‘Great Dying’, or the end-Permian extinction. The activity released toxic volumes of greenhouse gases into the atmosphere, raising air and sea temperatures.
It erased 96 per cent of marine species and 70 per cent of terrestrial species. When we pit this against recent volcanic activities, the comparison falls short because the human contribution to the carbon cycle is more than 100 times those of all the volcanoes in the world combined, according to the United States National Aeronautics and Space Administration (NASA).
Carbon emissions from the 2014 Holuhraun eruption in Iceland, the 2006 Etna Volcano in Italy and the 2010 Eyjafjallajökull eruption in Iceland have released 9,330 kilo-tonnes, 644 kilo-tonnes and 5,130 kilo-tonnes of carbon dioxide, respectively.
Read more: Mauna Loa & Mount Semeru volcanoes erupted within a week. Will they impact global climate?
In comparison, fossil fuel burning and cement production released 36.3 gigatonnes of CO2 into the atmosphere in 2015, according to the Global Carbon Budget 2016. So, the largest CO2-emitting eruption in the past 15 years produced only about 0.026 per cent of annual emissions from human activities.
Moreover, volcanoes in hot spots such as Hawaii, Iceland or the Canary Islands tend to emit more CO2 than those in zones such as Semeru.
In explosive volcanoes, magma erupts rapidly out of the volcano as pressure builds with a temperature range of 200-700 degrees Celsius, destroying everything in their path. The Mount Semeru eruption was less severe than Tonga, the underwater volcano that erupted on January 15, 2022.
Tonga generated flows that travelled 50 miles from their source. After the 1991 Mount Pinatubo explosion in the Philippines, there was a 0.5°C drop in the average global temperature over large parts of Earth from 1992 through 1993, with SO2 mass being 20 teragrams or 20,000,000,000kg.
Contrastingly, Mauna Loa released about 0.2 teragrams of SO2 this year, a reduction from 1984 when it released 1.2 teragrams. Roughly three teragrams of SO2 were released per year on average in the last decade, a study of 90 volcanoes found.
When a volcano releases SO2 particles, they mix with water vapour and form aerosols which can scatter and absorb incoming sunlight, according to NASA.
If an explosive eruption occurs in the 21st century, it could lower surface temperature and precipitation globally for one to three years and temporarily mask human-caused climate change, the Sixth Assessment Report of the Intergovernmental Panel on Climate Change suggested.
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