Research from Australia has shown a catastrophic decline in global wilderness areas over the past 20 years.

The research, led by James Watson of the Wildlife Conservation Society and the University of Queensland, showed that since the 1990s, one-tenth of all global wilderness - an areas twice the size of Alaska - has vanished. The Amazon and Central Africa have been hardest hit.

The researchers said their findings underscore an urgent need for international policies to recognise the value of wilderness and to address unprecedented threats to it.

Professor William Laurance from James Cook University, Queensland, who worked on the research team, said, ”Environmental policies are failing the world's vanishing wildernesses. Despite being strongholds for imperiled biodiversity, regulating local climates, and sustaining many indigenous communities, wilderness areas are vanishing before our eyes."

Prof Laurence’s research team mapped biologically and ecologically intact landscapes free of any significant human disturbance around the globe. The researchers then compared their current map of the wilderness to one produced by the same means in the early 1990s.

Their updated map shows that 30 million square kilometres (23 percent of the world's land area) still survives as wilderness, with the majority being located in North America, North Asia, North Africa and Australia. However, an estimated 3.3 million square kilometres of wilderness area has been destroyed in the past 20 years. Losses have been greatest in South America, which suffered a 30 percent loss of its wilderness, and Africa, which experienced a 14 percent loss.

"The amount of wilderness lost in just two decades is both staggering and saddening. International policies are urgently needed to maintain surviving wilderness before it's too late. We probably have just one or two decades to turn this crisis around," said Professor Laurance. "Once a wilderness is lost, it almost never comes back. The only option is to proactively protect the wilderness we have left.”

Wild areas support biodiversity, with species that are at risk from human incursion into their habitats and land use change still holding on in these areas, as well as crop wild relatives that could hold the keys to disease resistance and climate change adaption in domesticated crop plants. On top of this, wild areas like the Amazon Rainforest - referred to as the lungs of the planet - have a huge role to play in regulating climate change. Prof. Laurance said the United Nations and other international bodies have ignored globally significant wilderness areas in key multilateral environmental agreements, and that has to change as a matter of urgency.