Australia, New Zealand and the heads of state of 13 other Pacific states this week called for the phase-out of greenhouse gas pollution and acknowledged current efforts to tackle climate change are insufficient.

The Majuro declaration for Climate Leadership is surprisingly strong considering these types of documents are usually intent on satisfying the least ambitious parties – Australia and New Zealand, in this case. But the text, adopted at the 44th Pacific Island Forum, appeals for urgent action, commits all signatories to be "climate leaders" and calls for an energy revolution.

For me, two things stand out in particular.

First, the declaration explicitly recognises the need for a complete "phase down" of greenhouse gas emissions. Not "x% emissions by date y" – the sort of language that is important from a scientific perspective but has little meaning for the general public. The idea of a phase down makes clear that in the long run we need to eliminate greenhouse gas pollution altogether.

This implies that we must stop investing in the development of new sources of fossil fuels, or new infrastructure such as coal-fired power stations that lock in greenhouse gas pollution for 50 years or more.

It implies that we need to stop subsidising our continued dependence on fossil fuels. For every dollar we spend subsidising renewables, we spend six subsidising fossil fuels. Fatih Birol, chief economist for the International Energy Agency, calls fossil fuel subsidies "public enemy number one". And it implies that everyone must do his or her part to achieve not just a lo- carbon future, but in the long-term a net-zero one.

Second, the declaration recognises the complete insufficiency of current efforts to address climate change, and accepts a collective responsibility to act with urgency. It demonstrates that many Pacific Island states already have ambitious plans to transition away from fossil fuels, and calls on others around the world to follow their lead.

In essence, the agreement reframes the "I won't move till you move first" stance we've come to expect at the United Nations climate negotiations, to one of "I'm moving ahead and I invite you to move with me". Given that many countries are doing more at home than what they are prepared to commit to in the context of the negotiations, this kind of approach could be a game changer.

It must

The approach agreed on the Marshall Islands, pictured, could be a game changer. Photograph: Giff Johnson/AFP/Getty

be said, however, that the first to follow in the footsteps of these small island states should be their big brothers, Australia and New Zealand, whose actions do not quite live up to the powerful expectations expressed in the declaration. And, in the case of Australia, there's a real risk that recent progress will be undone following this weekend's election

I've been in Majuro throughout the forum proceedings, and have explored the streets, spoken to residents and walked the eroding beaches myself. It was a powerful experience to see what it means to live on the front lines of climate change.

I saw graveyards which were literally falling into the sea. I saw an island which had reportedly shrunk to a third of its size in the past 20 years. Driving down the island's only main road, there are places where you can see the lagoon out of one window and the open ocean out of the other – a stone's throw apart.

I saw two islands where previously there had been only one: the sea had breached the stretch of land which had once linked them. I saw palm trees at the water's edge which had toppled as the ground disappeared out from under them.

I saw the Bikini Atoll town hall, which serves as a reminder that the Marshallese people have been displaced before as a result of things done to them by people thousands of miles away.

And I met an inspiring young woman named Kathy Jetnil-Kijiner– a poet, storyteller and activist – who told me that if the Marshallese lose their land, they will lose their culture and their identity along with it. For this reason, she explained, the country doesn't have an evacuation plan in the event that sea level rise eventually claims their home. "Because that would be admitting defeat," she told me. "We are nothing without our islands."

And children. I don't think I've ever seen more open, curious, friendly kids than the Marshallese. Documents like the Majuro declaration will determine the future these children and every child on earth will inherit. The ambition of our documents, the veracity of our promises, and the speed and strength of our actions will protect their inheritance.