The Pacific Ring of Fire is a belt of hundreds of volcanoes that encircle the Pacific Ocean on three sides, at a length of about 40,000km. Plate tectonics created subduction zones there where one tectonic plate dives beneath another. This process forms oceanic trenches, and promotes the occurrence of earthquakes and the emergence of volcanoes. Some of them are already extinct, while others lie dormant—but many are still active. The kingdom of Tonga is situated in the zone of the Ring of Fire in the South Pacific. It consists of more than 170 islands of either volcanic origin or limestone from uplifted coral formations. In December 2014, a new island was born there out of the waters: a submarine volcano between the two islands Hunga Tonga and Hunga Ha’apai produced a massive eruption. It lasted until January 2015 and caused tsunamis that traveled as far as Chile and Russia. The newly formed landmass united the two originally separate islands. However, after another eruption in 2022, much of the new land was again swallowed by the ocean. Volcanism in the Pacific Ocean creates and destroys new islands, causing earthquakes and tsunamis that reach far away coasts. But Volcanism is also thought to have an impact on the global climate, through influencing the temperature of both the ocean surface and the stratosphere, through affecting the global water cycle and the monsoon circulation. Past climatic changes were linked to big volcanic eruptions. In the case of Hunga Tonga-Hunga Ha’apai however, this effect was quite small—scientists estimated, based on historical simulations, that the 2022 event decreased the mean global surface temperature by only 0.004°C in the first year following the eruption.
Sources: Global Volcanism Program, “Report on Hunga Tonga-Hunga Ha’apai (Tonga)”, Weekly Volcanic Activity Report, 12 January-18 January 2022.
Smithsonian Institution and US Geological Survey.
Zuo, M. et al., “Volcanoes and Climate: Sizing up the Impact of the Recent Hunga Tonga-Hunga Ha’apai Volcanic Eruption from a Historical Perspective”, Advances in Atmospheric Sciences, (2022).