For the past 15,000 years, a glacier on the northwestern Tibetan Plateau of China has hosted a party for some unusual guests: an ensemble of frozen viruses, many of them unknown to modern science.

Scientists recently broke up this party after taking a look at two ice cores from this Tibetan glacier, revealing the existence of 28 never-before-seen virus groups.

Investigating these mysterious viruses could help scientists on two fronts: For one, these stowaways can teach researchers which viruses thrived in different climates and environments over time, the researchers wrote in a paper posted on the bioRxiv database on Jan. 7.

Related: Photographic Proof of Climate Change: Time-Lapse Images of Retreated Glaciers

“However, in a worst-case scenario, this ice melt [from climate change] could release pathogens into the environment,” the researchers wrote in the study, which…