Innovations in genetic preservation now make it possible for species to live on long after their extinction.

The San Diego Zoo maintains a “frozen zoo” in which the cells of recently deceased or sedated endangered animals are carefully stored in liquid nitrogen tanks.  Researchers can then convert those cells into stem cells, and from there the stem cells can be reprogrammed into reproductive cells.

As reported by the Washington Post, over the span of 40 years, stainless-steel tanks at the San Diego Zoo have come to hold the genetic material of more than 10,000 individual animals from more than 1,000 species and subspecies.  For many threatened species, the difference between survival and extinction is held in a small, frozen vial.

Work at the frozen zoo has taken on new importance since the San Diego Zoo Safari Park lost 42-year-old white rhino Angalifu to cancer in December, leaving only five northern white rhinos in the world — and all unable to reproduce, according to the Washington Post.  However, researchers were able to harvest and preserve samples of the rhino’s genetic material shortly after its death, leaving hope that the species might have a fighting chance for survival.

New breakthroughs in preserving genetic material are not limited to San Diego.  Researchers at the University of Georgia’s Regenerative Bioscience Center recently created their own frozen zoo in which they believe endangered species of big cats could be saved.

The plan at the University of Georgia was devised by RBC Director Steven Stice and animal and dairy science assistant professor Franklin West.  West told CNN, “Essentially the genetics are immortal.  You could go in 20, 30, 200 years theoretically and thaw these stem cells out.  I’m very certain that it’s going to work.”

West also explained to CNN that the team has already performed a DNA extraction on Jalal, a Sumatran tiger that was euthanized in 2010, and a clouded leopard called Moby that died in 2013.  The genes of the animals are now in storage, waiting to be reprogrammed and possibly revive their respective species.

Although the bank is regarded as a genetic archive with the potential to bring back species from the brink of extinction, critics question whether it’s worth spending millions of dollars on species whose numbers are quickly dwindling.

“Screwing around with science to save a white rhino might be fun and I would like to see it preserved and am all for biodiversity, but it’s so far down the list of things we should be doing first,” Paul Ehrlich, a senior fellow at the Stanford Woods Institute for the Environment at Stanford University, told the Washington Post.  He explained that the root causes of species endangerment like population growth and climate change should be addressed with more urgency.

It remains to be seen whether or not the frozen zoo can truly save the world’s endangered animal populations, but this innovative approach at least gives hope for the future of at-risk animals.