France's President Emmanuel Macron, on Friday, stripped off his suit jacket to wander the wild forests of Papua New Guinea on a green-tinted charm offensive in the South Pacific.

Macron told Pacific leaders that France understands the threat they face from a warming Earth, from rising seas swamping low-lying islands to a loss of wildlife, wilder weather, and the financial costs they impose.

In Papua New Guinea, Macron wore no jacket, and at one point no tie, as he walked two kilometres with Prime Minister James Marape through the lush Varirata National Park, touting a French initiative to remunerate countries that preserve their old-growth forests.

Macron noted that natural forest covers 14 percent of the Earth's surface, stressing that huge reservoir of stored carbon are released when burned.

He added that the world already finances reforestation, arguing that there is no economic model to preserve the woodlands that already exist.

Macron further said a first Forest, Climate, Biodiversity project was signed with Papua New Guinea, to be managed by the French development agency with 60 million euros in financing from the European Union.