Toronto, Sep 9 (IANS): An estimated 3.3 million square kilometres -- almost 10 per cent -- of wilderness area has been lost over the last 20 years, finds a study that shows catastrophic declines in wilderness areas around the world.

The alarming losses comprise a tenth of global wilderness since the 1990s -- an area twice the size of Alaska and half the size of the Amazon basin. 

The losses have occurred primarily in South America, which has experienced a 30 per cent decline in wilderness, and Africa, which has experienced a 14 per cent loss, the study said.

"The amount of wilderness loss in just two decades is staggering," Oscar Venter from the University of Northern British Colombia in Canada. 

"If we don't act soon, there will only be tiny remnants of wilderness around the planet, and this is a disaster for conservation, for climate change, and for some of the most vulnerable human communities on the planet," added James Watson from the University of Queensland in Australia. 

For the study, the researchers mapped wilderness areas around the globe, with "wilderness" being defined as biologically and ecologically intact landscapes free of any significant human disturbance. 

The findings underscore an immediate need for international policies to recognise the value of wilderness areas and to address the unprecedented threats they face, the researchers noted.

"We need to recognise that wilderness areas, which were considered to be de-facto protected due to their remoteness, is actually being dramatically lost around the world," Venter said.

"Without proactive global interventions we could lose the last jewels in nature's crown. You cannot restore wilderness, once it is gone, and the ecological process that underpin these ecosystems are gone, and it never comes back to the state it was. The only option is to proactively protect what is left," Venter noted.

The United Nations and other international policy mechanisms have ignored globally significant wilderness areas in key multilateral environmental agreements and this must change, the researchers concluded, in the paper published in the journal Current Biology.