Earth is constantly molded by fire and ice, and not in a poetic sense.
These physical forces singe or scour our planet's surface with fiery eruptions or the unstoppable march of glaciers.
On the chilly side, Earth has experienced at least five ice ages, including some potential snowball or slushball episodes, if we delve into deep time.
We're in a geological ice age right now, in fact, but we're currently in a balmier interglacial period, which began approximately 11,700 years ago, around the time many fluffy megafauna started going extinct.
These warmer periods fluctuate with colder, icier periods that host great glaciers – what we colloquially call 'ice ages' and associate with woolly mammoths and shivering cave-dwellers huddling over meager fires.
Actually, the next of these ice ages may have already begun about 2,000 years ago, only to be cut short by human-driven climate change, a new study published in the journal Science suggests.
"It was just getting started, everything was normal, the next glaciation was about to happen – and yet it stopped," says Nicolás Young, a geochemist at Columbia University and the study's first author.
The study focused on the Laurentide Ice Sheet ...