May 22, 2022 7:06 pm

The eruption of the Hunga Tonga volcano: consequences on the climate?

Francis Martin Leon 6 min
The caldera of the Tambora volcano today. Source: Wikipedia.

In the history of the Earth, volcanic activity has always been a determining element for the climate and sometimes also for its change.. In fact, the largest volcanic eruptions in history have been able to cause a drop in the global temperature of the Earth. doThe same will happen with the recent eruption of the volcano South-East People?

Overview of historical eruptions

In 1815, towards the end of the Little Ice Age (1300-1850), the eruption of a volcano in Indonesia (Tambora) released a large amount of sulfur dioxide in the air. The following year, 1816, is considered “the year without summer“. Freezes and snowfall were recorded in late spring and early summer in the northeastern United States and northern Europe.

The most important eruption in recent history, in the Philippines (Pinatubo volcano) in 1991, caused a major cooling of the planet that lasted about two years. The reason: the huge amounts of sulfur dioxide released in the stratosphere spread across the planet. The aerosols associated with it (sulfuric acid condensation creates sulfate aerosols, which reflect part of the solar radiation) have made the atmosphere less permeable to the sun’s rays.

The propagation of this column of aerosols was very fast: in about three weeks, it went around the Earth at the latitude of the volcano, and in about a year, the stratosphere of the entire globe was affected by these aerosols, from the Pole North to the South Pole.

Global solar radiation decreased by 4%, with local peaks of 7-15%. This resulted in a cooling of the land surface in the northern hemisphere of 0.5 to 0.6 °C, corresponding to about 4 W/m2. Globally, the cooling was around 0.4°C with the maximum being reached between 1992 and 1993. Climate models used at the time were able to accurately predict the cooling caused by this volcanic eruption.. The plume of ash and gas reached a height of 40 km and released around 17 million tonnes (17 billion kilograms) of sulfur dioxide into the lower stratosphere. That’s about twice as much as the 1982 eruption of Mexico’s El Chinchón volcano released into the stratosphere.

Main sources of emission of sulfur dioxide. Anthropogenic emissions (since 2005, cyan, red, and green symbols; oil and gas extraction/processing, power generation, smelters) and volcanic emissions (since 1979, orange triangles). Explosive volcanoes are the phenomena that effectively inject sulfur dioxide into the stratosphere. POT

The recent eruption of Hunga Tonga Hunga Ha’apai

The current eruption at Hunga Tonga Hunga Ha’apai has reached a height currently estimated at 30 km (LIDAR data), although according to satellite data the upper part of the gas cloud may have reached a height of 40 km (this figure is still being verified by the scientific community). Therefore, Hunga Tonga Hunga Ha’apai also managed to inject sulfur dioxide into the lower stratosphere.

Little SO2 injected into the atmosphere

However, heThe possible consequences for the climate do not depend on the height that the plume can reach, but on the amount of sulfur dioxide that it manages to release into the stratosphere. The amount of aerosols released by Hunga Tonga Hunga Ha’apai in the lower stratosphere is much smaller than that released by Pinatubo: current estimates put it at “only” 0.4 million tons (400 million kilograms), or just 2% of the Pinatubo.

No impact on overall temperature

climatologists, supported by the first results of numerical model simulations, do not expect a significant drop in global temperature. The decline, in addition to being temporary, could be even less than a tenth of a degree centigrade. This is nothing compared to the increase in the global average temperature of the last 150 years, which now reaches +1.1 °C (+2.1 °C in Switzerland). In addition, the average temperature is constantly increasing, a factor that could mask a possible minimum solar radiation due to sulfur dioxide and aerosols released by the Hunga Tonga Hunga Ha’apai eruption.

At the environmental level, the main concern related to the volcano is rather related to the amounts of sulfur dioxide trapped in the troposphere. In fact, the troposphere is the lowest part of the atmosphere where weather phenomena occur: these concentrations could give rise to regional acid rain. the continent with higher risk, given its position relative to the volcano and the dispersion of sulfur dioxide, seems to be australia. A continent that, after exceptional heat waves, devastating fires and consecutive floods, finds no respite again.

Sulfur dioxide cloud over Australia. THAT

22 January 2022

MeteoSuisse Blog

This entry was posted in Reports on 23 Jan 2022 by Francisco Martín León

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