There have been "catastrophic declines" in wilderness areas across the planet in the past 20 years, according to an international study led by the University of Queensland.
James Watson, from the University of Queensland's School of Geography, Planning and Environmental Management, said that the findings showed losses comprising a 10th of the world's wilderness, with Central Africa and the Amazon the areas hardest hit.
"The findings underscore an immediate need for international policies to recognize the value of wilderness and to address the unprecedented threats it faces," Watson said in a statement.
"Globally important wilderness areas are completely ignored in environmental policy, 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," Watson added.
The study looked at - and mapped - wilderness across the planet, defining 'wilderness' as "biologically and ecologically intact landscapes free of significant disturbance," the University of Queensland said.
Their map was compared to one produced using the same technique from the early 1990s, with the most recent map showing that an estimated 3.3 million kilometers squared of wilderness – nearly 10 percent – had been lost.
The report said that the Amazon was an area threatened by a host of factors, including industrial forestry, climate change and oil and gas exploration.
The scale of deforestation in the Amazon, for example, is a pressing concern. According to the World Wildlife Fund, roughly 17 percent of forest there has been lost over the last 50 years.
"The amount of wilderness loss in just two decades is staggering and very saddening," Watson said.
"We need to recognize that wilderness is being dramatically lost and that without proactive global interventions we could lose the last jewels in nature's crown," he added.
"You cannot restore wilderness. Once it is gone, the ecological process that underpins these ecosystems are gone, and it never comes back to the state it was."