Scientists from 15 organisations across the world, including the University of Adelaide, have discovered a huge area of forest using new techniques.
An area of forest more than half the size of Australia has been discovered, dotted across several continents.
Researchers from the University of Adelaide are among the team led by the United Nations' Food and Agriculture Organisation (FAO) to have uncovered the 467 hectares of previously unreported forests and woodlands.
The forests have been identified in drylands in the Sahara desert, around the Mediterranean, southern Africa, central India, coastal Australia, western South America, north-east Brazil, northern Colombia and Venezuela and northern parts of Canada and Russia.
They have previously been difficult to measure because the density of trees is low, making them hard to detect using satellite images and other technologies.
A new photo-interpretation tool developed at the FAO, called Collect Earth, has overcome this challenge by offering a simple way to check the number and density of trees in arid areas.
Researchers from 15 organisations have used the tool to analyse very high-resolution satellite images of more than 210,000 dryland monitoring sites, discovering the new forests and woodlands in the process.
The amount discovered is equivalent to 60 per cent of the size of Australia and has increased the estimate of global forest coverage by 10 per cent.
The University of Adelaide's Plant Conservation Biology Chair Andrew Lowe says the finding is "very, very significant" and could provide new ways to ease climate change.
"Dryland regions have a greater capacity to support trees than previously perceived and understood," Professor Lowe said in a statement.
"Dryland could, therefore, provide a unique chance to mitigate climate change through large-scale conservation and afforestation actions."
The findings of the study were published in the journal Science on Friday.