It’s a bleak revelation — a new study reveals that about a tenth of the Earth’s wilderness has been lost since the 1990s. Over the last 20 years, a total area half the size of the Amazon and twice the size of Alaska has been depleted.

The researchers behind the study, published in the journal Current Biology, say they hope that the sobering revelation that rich natural habitats like the Amazon have been decimated in a relatively short amount of time will act as a wakeup call to global leaders to emphasize conservation efforts in their environmental protection policies.

When asked why these important, at-risk areas haven’t been better protected, study lead author James Watson points the finger at government leaders around the world.

“Put simply — no international treaty talks about the importance of wilderness or has any targets that nations must follow that limit their (wilderness areas’) loss,” Watson, an associate professor at the University of Queensland in Australia, wrote in an email to CBS News.

The study shows […]