In times of global warming, a volcanic eruption can alter the Earth’s temperature briefly.
Thousands of people have been asked to evacuate within 10km of Indonesia’s Mount Agung and more than 443 flights have been cancelled as the Bali airport remained closed for the third consecutive day. But scientists say the eruptions on Agung could cool the planet temporarily if it spits out enough sulphur.
Volcanoes spew millions of tonnes of ash and gases that can spread through the atmosphere, form compounds like aerosols and scatter sunlight that can bring down temperatures.
But there are conditions for this occurrence. The eruption has to be rich in sulphur and large enough to have a real impact on the planet’s temperature, explained NASA climate scientist Chris Colose.
“To have a notable climate impact, there needs to be an explosive enough eruption (to get material in the stratosphere) and a sulfur-rich eruption (the SO2 converts to sulfate aerosol, which is what radiatively matters),” wrote Colose.
If these conditions are met, the eruption cools the surface/troposphere and warms the stratosphere, the opposite of both patterns associated with CO2 increases. But both are very short-lived (~years).
— Chris Colose (@CColose) November 27, 2017
In the stratosphere, the sulfur dioxide spluttered by a volcano combines with water to form sulfuric acid aerosols, making a haze of tiny droplets that reflect incoming solar radiation, cooling the Earth’s surface.
Data from NASA’s Aura satellite showed on Monday that Agung had sprayed sulphur dioxide into the air.
Data from @NASA Aura satellite shows high SO2 concentrations from Mount #Agung yesterday in #Bali, #Indonesia. People on the ground witnessing the #volcano emitting thick ash clouds and glowing lava. More satellite imagery: https://t.co/oVYhIsjXNx pic.twitter.com/U3wPxQtfHc
— NOAA Satellites (@NOAASatellites) November 28, 2017
If Agung meets all the criterion, it could reduce global temperatures by 0.1-0.2 degrees Celsius, but the change will likely be felt temporarily, according to Climate Brief. The temperatures will be back to the normal levels by 2023.
Although its impact is yet to be seen, Mount Agung’s last major eruption in 1963 had lowered global temperatures by 0.1 to 0.2 degrees Celsius, Vox reported. On ground, however, it killed 1,100 people.
Authorities have told 100,000 people to leave an area extending 10 kilometers from Mount Agung as it belches grey and white ash plumes, the low clouds hanging over the volcano at times hued red from the lava welling in the crater.
Officials also extended the closure of Bali’s international airport for another 24 hours due to concerns the thick volcanic ash could harm aircraft.
Experts have said a larger, explosive eruption is possible or Agung could stay at its current level of activity for weeks.
Indonesia sits on the Pacific ‘Ring of Fire’ and has more than 120 active volcanoes.
(With agency inputs)
