A previous report in 2002 estimated that only 10 percent of gorillas would remain by 2030. The author of the 2002 report and of the newly released one said that estimate now appears too optimistic.
"We fear now that the gorillas may become extinct from most parts of their range in perhaps 15 years," U.N. Environmental Program's Christian Nellemann said.
One of the dangers gorillas now face is a large increase in logging for timber that is mostly destined for Asia, particularly China, said Nellemann, also editor-in-chief of the newly released report "The Last Stand of The Gorilla."
Militant factions have also taken over gorilla land, making the protection of gorillas extremely difficult, he said. Increasing human populations and the deadly ebola virus are also killing gorillas.
Achim Steiner, executive director of UNEP, said that logging and mining camps hire poachers to supply refugees and markets with the meat of wild animals, including gorillas.
The report calls for greater scrutiny of European and Asian companies using subsidiaries to extract timber and minerals from central Africa.
"This is tragedy for the great apes and one also for countless other species being impacted by this intensifying and all too often illegal trade," Steiner said in a statement. "In short it is environmental crime and theft by the few and the powerful at the expense of the poor and the vulnerable."
David Higgins, manager of the Interpol Environmental Crime Program, said that gorillas are a victim of the contempt shown by organized crime groups toward national and international laws aimed at defending wildlife.
The report, however, contained some good news as well. An unpublished survey of one area of eastern Congo in the centre of the conflict zone discovered 750 previously unknown critically endangered eastern lowland gorillas.
"What we are worried about is that these gorillas are disappearing faster than we can actually mobilize resources to save them," said Nellemann, who called for increased resources for UNEP and Interpol to protect great apes.
There are four distinct types of gorilla. Three are listed as critically endangered and one is listed as endangered.
Watch Anderson Cooper's Piece on African Gorillas on "60 Minutes":