The Australian government's climate change adviser, Ross Garnaut, says Papua New Guinea has the potential to become the world's first zero carbon emissions country.
But the professor has told a climate change conference in Port Moresby that PNG must first tackle serious threats to its forests.
Conference delegates were told a five-year study had found that more than half of PNG's forests could be lost or badly damaged by 2021 due to wasteful logging and population growth.
The report by the University of PNG and the Australian National University says PNG must live up to its statements about environmental protection or continue to lose millions of hectares of forest.
Professor Garnaut said PNG must set a national target for reducing greenhouse emissions.
He the first step, and most important, is PNG has to take a decision that it is serious about effective forest management, including measurement of changes in the carbon content of the forest.
He said if PNG decides this is important enough to make the effort then there will be a lot of international support.