Free Astronomy Magazine January-February 2018

30 JANUARY-FEBRUARY 2018 EARTH changes were greater for larger BC ejections. Changes in the atmosphere showed a rapid response immediately after the impact: up to 0–0.5 °C, 2–3 °C, 4–6 °C, 8–10 °C, and 8–11 °C cooling of the global mean surface air temperature, 0–1 °C, 4–5 °C, 6–9 °C, 10–16 °C, and 10–18 °C cooling of the global mean surface air tempera- ture on land, and 0–15%, 25–50%, 45–70%, 65–80%, and 75–85% decreases in global mean precipitation on land for 20-, 200-, 500-, 1500-, and 2600-Tg BC ejec- tion cases, respectively, within a few years after the impact. Temperature and precipitation gradually re- covered within the follow- ing 10 years. Seawater temperature changes exhib- ited a slower response fol- lowing the impact, and cooling at shallower water P hanerozoic faunal changes with approximately 13% probability following the Chicxulub aster- oid impact. Changes in fauna are based on extinc- tion rates. Changes through the K–Pg boundary mass extinction are enhanced by a change in the main terrestrial fauna from dinosaurs to mammals. [K. Kaiho & N. Oshima, Scientific Reports] A piece of the asteroid that made the Chicxu- lub Crater. [Pho- tograph by Faith Tucker, NASA]