Australian geologists have used plate tectonic modelling to determine what most likely caused an extreme ice-age climate in Earth’s history, more than 700 million years ago. The researchers have proposed that all-time low volcanic carbon dioxide emissions triggered the 57 million year-long global ‘Sturtian’ ice age. The extended ice age stretched from 717 to 660 million years ago, a period well before the dinosaurs and complex plant life on land existed. The team went back to a plate tectonic model that shows the evolution of continents and ocean basins at a time after the breakup of the ancient supercontinent Rodinia. They connected it to a computer model that calculates carbon dioxide degassing of underwater volcanoes along mid-ocean ridges. The researchers found that the start of the Sturtian ice age precisely correlates with an all-time low in volcanic carbon dioxide emissions. In addition, the carbon dioxide outflux remained relatively low for the entire duration of the ice age. The study (Geology) helps our understanding of the functioning of the Earth’s built-in thermostat that prevents the Earth from getting stuck in overheating mode. It also shows how sensitive the global climate is to atmospheric carbon concentration.
