Julien Emile-Geay, USC Dornsife College of Letters, Arts and Sciences
Thanks to humans, the concentration of planet-warming carbon dioxide in the atmosphere is now 50% higher than before the industrial era. These gases are raising Earth’s temperature.
Lava flow moves in the Leilani Estates subdivision near Pahoa on the island of Hawaii, May 6, 2018.
USGS via AP
Fountains of lava from Hawaii’s Kilauea volcano are dramatic, but the most deadly impacts of volcanic eruptions are toxic gases and ash and mud flows.
Volcanoes produce large amounts of a gas that interacts with air to produce sulfate aerosols, which act as tiny mirrors in the atmosphere to reflect sunlight – and heat.
NASA
Blocking the sun by injecting tiny particles in the atmosphere – called solar geoengineering – can lower the Earth’s temperature but has some real costs. Economists run the numbers.