Tiny meteorites suggest ancient Earth had a carbon dioxide–rich atmosphere
High levels of CO2 could have produced observed chemical alterations in cosmic dust
![micrometeorites](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2020/01/012720_cg_co2-archean_feat.jpg?fit=1028%2C579&ssl=1)
As micrometeorites (such as those shown) zoom through Earth’s atmosphere, they can melt and chemically react with atmospheric gases. New simulations of such reactions in 2.7-billion-year-old meteorites suggest Archean Earth’s atmosphere had a lot of CO2.
D.E. Brownlee