Hunga volcano eruption's unexpected Southern Hemisphere cooling effect challenges geoengineering assumptions

When Hunga Tonga–Hunga Haʻapai, an underwater volcano near Tonga in the South Pacific Ocean, erupted in 2022, scientists expected that it would spew enough water vapor into the stratosphere to push global temperatures past the 1.5 C threshold set by the Paris Accords. A new UCLA-led study shows that not only did the eruption not warm the planet, but it actually reduced temperatures over the Southern Hemisphere by 0.1 C.