WASHINGTON - Scientists think they've figured out the falling dominoes that led to Earth's largest mass extinction and worry that human-caused climate change puts the planet on a vaguely similar path.

Some 250 million years ago, about 90 per cent of sea life and 70 per cent of land life went extinct in what is now called the Great Dying. Scientists have long speculated that massive volcanic outbursts triggered the cataclysmic event, but how that worked was still a bit fuzzy.

A new study in Thursday's journal Science used complex computer simulations to plot out what happened after the volcanoes blew: It led to ocean temperatures rising by about 20 degrees (11 degrees Celsius), which then starved the seawater of oxygen. That hot oxygen-starved water caused the mass marine die-off.