When an underwater volcano in Tonga erupted in January, it belched out more than ash and volcanic gases; it also spewed 58,000 Olympic-size swimming pools' worth of water vapor into Earth's atmosphere, a new study finds. This water vapor could end up being the most destructive part of the volcano's eruption because it could potentially exacerbate global warming and deplete the ozone layer, according to the study. When the Hunga Tonga-Hunga Ha'apai volcano erupted on Jan. 15, it became the most powerful explosion on Earth in more than 30 years, with an equivalent force of 100 Hiroshima bombs.