Humans have literally decimated Earth's wilderness, study finds

Ten percent of Earth's wilderness has disappeared since the 1990s, according to a new study published in the journal Current Biology. 

Over the last 20 years, we've lost a total area amounting to twice the size of Alaska, researchers report. But, experts say, there's still time to save the remaining wilderness areas – and they hope the recent findings will spur change. 

At the moment, only about 23 percent of the world's land area is made up of wilderness, the study found. Most of this wilderness can be found in North Asia, North Africa, Australia, and North America (primarily the northern parts of Canada). South America has experienced the greatest loss, with a 30 percent decrease since the '90s, and Africa follows with 14 percent. 

"The wilderness decline around the world is most in the tropical biomes​, the tropical rain forests​ have lost a lot of wilderness," study co-author Oscar Venter, of the University of Northern British Columbia, told CBS News. "A lot of the Amazon has been lost, the mangrove ecosystems, which are really important wilderness areas have been hit. They are a nursery ground for a lot of the world’s wildlife – young fish are reared in these mangrove ecosystems​, they are a base for a lot of the fisheries. Now, there is almost no wilderness left in the mangroves."

The researchers attribute the loss of wilderness to a lack of action on the part of government leaders around the world. 

"Globally important wilderness areas – despite being strongholds for endangered biodiversity, for buffering and regulating local climates, and for supporting many of the world's most politically and economically marginalized communities – are completely ignored in environmental policy," said lead author James Watson, of the University of Queensland in Australia and the Wildlife Conservation Society in New York, in a press release. 

Fortunately, all hope is not lost. The study reports that nearly 80 percent of the remaining wilderness is made up of large chunks of land, increasing the chances of survival for animals living there. However, Mr. Watson added, leaders will need to act fast to protect this remaining wilderness. 

"International policy mechanisms must recognize the actions needed to maintain wilderness areas before it is too late," he said. "We probably have one to two decades to turn this around." 

Activists can help by urging policymakers to take action, Mr. Venter told CBS, praising "grassroots movements" for raising awareness of importance of conservation. Such movements can be powerful; in Brazil, deforestation rates decreased by 70 percent between 2005 and 2014 due to the conservation efforts of soybean farmers and cattle ranchers. 

"What can happen in the near-term is to encourage major policy mechanisms to actually speak to wilderness values and wilderness protection," Venter said. "Speak to your local officials, make sure you can set values on wilderness preservation​ that can occur through actual policy, where we set targets for wilderness protection areas."