New clues in a mass murder that took place 252 million years ago points to a suspect: Ocean acidification may have driven the largest extinction of animals the world has ever seen. Carbon dioxide belched out by volcanic eruptions during the Permian period could have caused the oceans’ chemistry to change. That’s worrisome because CO2…

Carbon dioxide may be public enemy number one in the fight against global warming. But taking aim at methane and soot has a better chance of keeping the planet cooler in the short run, a new study finds.