Here’s why the South Pole froze over before the North Pole

While it once was temperate and lush, Earth’s southernmost continent Antarctica froze over about 34 million years ago, covered by an ice sheet that today is up to around 3 miles (5 ​km) thick. By contrast, the planet’s northernmost realm, the Arctic region, did not freeze over for another 25 million years.

This polar asymmetry long has puzzled scientists, but ‌researchers now may have solved the mystery....