Scientists are getting closer to unlocking the mysterious event that effectively ended the Permian period and killed 90 percent of all marine life and 70 percent of terrestrial species around 250 million years ago, according to Science World Report. Rather than focus solely on the volcanic explosion believed by past researchers to trigger the mass extinction, a team of scientists developed models to better understand the eruption's after effects.

Led by MIT's Benjamin Black, the team's 3-D models demonstrated how gas released from volcanic rock in a region of Russia called the Siberian Traps (where the eruption occurred) led to highly acidic rain, according to the press release. The gas, in the form of sulfur dioxide and carbon dioxide, created rain acidic enough to rid the soil of nutrients, kill plants, and affect other terrestrial and sea creatures.

Increased carbon dioxide emissions -- in combination with other ozone-depleting substances like methyl chloride that were likely released -- had another detrimental effect, or the same effect it's having today: The gas compromised the ozone layer. Thus, living organisms were subject to higher global temperatures, greater ultraviolet exposure, and a massive dip in Ph levels, according to the release.

The erraticity of temperature, UV exposure, and Ph levels also made life on earth difficult. Volcanic eruptions were "episodic," meaning acid rain and ozone depletion came in waves as plants, animal, and other living creatures were subject to wild fluctuations in environmental conditions, according to the release.

It took millions of years for earth to recover the biodiversity it lost when Siberian volcanoes erupted at the end of the Permian Era. From that era came the dinosaurs, a species that would eventually meet its own dramatic extinction millions of years later.