The first measured sea temperature from a snowball Earth episode, 717 million years ago, has been confirmed as the coldest in Earth's history. The analysis suggests that seawater during the Sturtian snowball glaciation, which lasted 57 million years, could have been up to 4 times saltier than modern ocean water during this period. The researchers also analyzed isotopes of strontium and barontium to determine that the seawater of the Australian National University's snowball Earth was up to a 4 times heavier than modern seawater. The discovery was made in Nature Communications. The Sturtians snowball was a runaway climate catastrophe due to ice reflecting more sunlight than land or water, leading to the planet being buried under glaciers.