Some 717 million years ago, glaciers covered the globe. Earlier eruptions may have triggered the event. CLAUS LUNAU/SCIENCE SOURCE ***************************************************** About 717 million years ago, a climate catastrophe struck the planet, as temperatures plunged and glaciers enveloped the globe. The cause of this “Snowball Earth” episode has been mysterious, but it took place around the same time as a massive outburst of volcanism. Many researchers thought there might be a connection. But the timing was uncertain. Now, more precise dates, reported last month in Earth and Planetary Science Letters (EPSL) and in November 2022 in Science Advances, show the eruptions...