Will The Eruption Of Hunga Tonga-Hunga Ha’apai Volcano Affect Earth’s Climate?

In April 1991, steam explosions were first observed on a little-known volcano called Mount Pinatubo on the island of Luzon in the Philippines. Within 11 weeks, on the afternoon of June 15, the volcano erupted ten billion tons of pumice and an estimated 17 billion tons of sulfur-dioxide. The VEI 6 eruption of Mount Pinatubo was the second-largest eruption of the 20th century. Satellite images tracked the eruption column forming an umbrella cloud reaching a maximum diameter of over 1100 kilometers and a maximum elevation of 35 kilometers above sea level. The ash and sulfur-dioxide reacted with water vapor to form over 30 billion tons of sulfuric-acid droplets and other aerosols. The aerosols quickly spread around the tropics and high latitudes, carried there by atmospheric currents along Earth’s equator. Over the following months, the aerosol cloud climbed higher into Earth’s atmosphere, forming a barrier and scattering or reflecting parts of the sunlight. By August 1991, five percent less solar radiation was reaching Earth’s surface, and in response, Earth cooled down by 0.5 degrees for the coming two to three years.

On Saturday, the Hunga Tonga-Hunga Ha’apai volcano erupted with a VEI 5 explosion in spectacular fashion near the Pacific nation of Tonga, with a volcanic plume and a blast wave seen from space by various weather satellites. An especially powerful explosion produced an ash plume about 150 kilometers (about 100 miles) across and 20 kilometers high, reaching Earth’s upper atmosphere. The blast wave travelled twice around the world, as 16 hours after the eruption two peaks in atmospheric pressure were measured at various weather stations in Europe.

Could the Hunga Tonga-Hunga Ha’apai eruption have similar effects on the climate as previous big and explosive eruptions?

It seems unlikely at the moment.

Preliminary observations suggest that the volcano erupted “only” 400.000 tons of sulfur-dioxide so far. Based on research done after the Pinatubo eruption, it is believed that a volcano must at least erupt 5 billion tons to affect global temperatures.

The effect of a volcano on the climate depends on various factors, including the magnitude of the explosions, the elevation of the eruption column, the sulfur content of the lava, and the site of the eruption.

Volcanic eruptions with marked cooling effects in the past, like Pinatubo in 1991 or Tambora in 1815, happened near the equator, where atmospheric circulation will carry the volcanic cloud around the globe. Hunga Tonga-Hunga Ha’apai is located further south in the Pacific Ocean, likely limiting aerosol dispersal.