The world's last wilderness areas are rapidly disappearing due to human activities, according to a study which found that between 1993 and 2009 an area larger than India was lost to settlement, farming, mining and other pressures.
Researchers from the University of Queensland (UQ) in Australia said explicit international conservation targets are critically needed to protect the world's remaining wilderness.
The study, published in the journal 'Nature', mapped intact ocean ecosystems, complementing a 2016 project charting remaining terrestrial wilderness.
Professor James Watson, from UQ's School of Earth and Environmental Sciences, said the two studies provided the first full global picture of how little wilderness remains.
"A century ago, only 15 per cent of the Earth's surface was used by humans to grow crops and raise livestock," he said.
"Today, more than 77 per cent of land -- excluding Antarctica -- and 87 per cent of the ocean has been modified by the direct effects of human activities," Watson said.
"It might be hard to believe, but between 1993 and 2009, an area of terrestrial wilderness larger than India -- a staggering 3.3 million square kilometres -- was lost to human settlement, farming, mining and other pressures," he said.
The researchers said in the ocean, the only regions that are free of industrial fishing, pollution and shipping are almost completely confined to the polar regions.
UQ Postdoctoral Research Fellow James R. Allan said the world's remaining wilderness could only be protected if its importance was recognised in international policy.
"Some wilderness areas are protected under national legislation, but in most nations, these areas are not formally defined, mapped or protected," he said.
"We need the immediate establishment of bold wilderness targets -- specifically those aimed at conserving biodiversity, avoiding dangerous climate change and achieving sustainable development," said Allan.