Changing global environments and habitat destruction are driving reptile species to extinction, according to new report published Friday in the journal Biological Conservation.

According to researchers from the Zoological Society of London (ZSL) and the IUCN Species Survival Commission (SSC), nearly one in five of the world's lizards, snakes, turtles and crocodiles (among others) are under threat of extinction, with 12% of that group classified as 'critically endangered.' 

“Reptiles are often associated with extreme habitats and tough environmental conditions, so it is easy to assume that they will be fine in our changing world," said lead author Dr. Monika Böhm. “However, many species are very highly specialized in terms of habitat use and the climatic conditions they require for day to day functioning. This makes them particularly sensitive to environmental changes.”

The first of its kind summary of the global conservation status of reptiles, the study found an uneven distribution of threat among the world's estimated 10,000 species. According to the paper, an alarming 30% of all freshwater reptiles are close to extinction with half of the world's freshwater turtles alone under threat. The paper credits this partly to their trade on international markets.

"The proportion of threatened reptile species is highest in freshwater environments, tropical regions and on oceanic islands," the paper says. "Levels of threat remain particularly high in tropical regions, mainly as a result of habitat conversion for agriculture and logging."

Although terrestrial reptiles are at a lower risk, species are often restricted to specific habitats with low mobility, making them particularly susceptible to human pressures.

Collectively referred to as ‘reptiles’—snakes, lizards, amphisbaenians (also known as worm lizards), crocodiles, and tuataras—first appeared on the planet around 300 million years ago. According to the ZSL, they play "a number of vital roles in the proper functioning of the world’s ecosystems, as predator as well as prey."

"The findings sound alarm bells about the state of these species and the growing threats that they face globally," said Philip Bowles, Coordinator of the Snake and Lizard Red List Authority of the IUCN Species Survival Commission. "Tackling the identified threats, which include habitat loss and harvesting, are key conservation priorities in order to reverse the declines in these reptiles.”