Greenpeace International says the governments of Australia and New Zealand must change their attitudes to climate change and be more supportive of Pacific Island countries.
The small island nations are seeking a legally binding climate agreement from world leaders at the Paris COP 21 summit in December.
But Greenpeace's executive director, Kumi Naidoo, says the position taken by the Pacific countries is weakened without their most powerful neighbours on board.
"A non-binding agreement is not going to deliver what is needed and for that reason we need New Zealand and Australia to actually show much greater alignment to what the science is saying. Because you know what is at stake here is not, we are not fighting for something as nebulous as saving the planet. What we are fighting here for is to secure our children and their children's futures."