Scott Morrison will unveil a $500m climate change and oceans funding package for the Pacific region when he attends the Pacific Islands Forum leaders meeting in Tuvalu this week.

The funding package, which will use existing aid funds to help Pacific nations invest in renewable energy and climate and disaster resilience, will build on the $300m given by the government for that purpose in 2016-2020.

“The Pacific is our home, which we share as a family of nations. We’re here to work with our Pacific partners to confront the potential challenges they face in the years ahead,” said the prime minister.

The government also announced it had set aside $140m from the aid budget to encourage private sector investments in low-emission, climate-resilient projects for the Pacific and south-east Asia.

Morrison will face strong pressure from other Pacific leaders when he arrives in Tuvalu on Wednesday, many of whom have already issued warnings that they want commitments from Australia at this forum for concrete action to reduce emissions and to move away from coal-fired power.

On Monday, during a one-day climate conference hosted by the Tuvalu government, the Fijian prime minister, Frank Bainimarama, a global leader in the fight against climate change, issued a direct appeal to Australia to move away from coal-powered energy and asked its government “to more fully appreciate” the “existential threat” facing Pacific nations.

“Put simply, the case for coal as an energy source cannot continue to be made if every nation is to meet the net zero emission target by 2050 that has been set by the UN secretary general and every other responsible leader of the climate struggle,” said Bainimarama, who is a former president of the UN’s leading climate body COP (Conference of the Parties).

The forum is being hosted in Tuvalu, a country of 11,000 people located three hours north of Fiji, which is at serious risk from rising sea levels as a result of climate change. Climate change is at the heart of this year’s forum, from the moment leaders arrive at Funafuti airport and are greeted by the children of Tuvalu, who sit submerged in water, in a moat built around the model of an island, singing: “Save Tuvalu, save the world.”

Speaking to Guardian Australia ahead of the forum, the prime minister of Tuvalu, Enele Sopoaga, said he had concerns about Australia’s coal policy and its use of carryover credits as a means of reducing emissions. He said the positive relationship with Australia could change if the future of his people was not taken seriously.

“I hope we can be more understanding that the people of Tuvalu and small island countries are already submerged, are already going underwater,” Sopoaga said.

“If our friend Australia does not show them any regard, any respect, it is a different thing, we cannot be partner with that thinking. I certainly hope we do not come to that juncture to say we cannot go on talking about partnerships regardless of whether it is [the Australian government’s Pacific] Step-Up or [New Zealand’s Pacific] Reset, while you keep pouring your coal emissions into the atmosphere that is killing my people and drowning my people into the water.”

Simon Bradshaw, Oxfam Australia’s climate advocacy lead who is in Tuvalu for the forum, said that while this money would be welcomed by Pacific leaders, it would not mean the Australian government was off the hook when it came to reducing emissions.

“Australia couldn’t come here empty-handed, they were going to have to bring something, but a new commitment of climate finance ... that’s not enough,” said Bradshaw.

“It’s one part of the equation, it’s an important part, but really it carries no meaning if it’s not accompanied by new strong commitments from Australia to drive down its emissions, its carbon pollution, to move beyond coal, to play its part in limiting warming to one and a half degrees, which we’ve heard repeatedly is crucial to survival in the region.”

Bradshaw said that Pacific leaders had never been as strident in their calls for urgent action to reduce emissions and preserve their homes and islands as they have been in the lead-up to this forum.

“They’re absolutely clear that Australia’s rising emissions, our coal exports are threatening their very survival,” he said. “From all the talk we’ve heard this week, whereas this commitment will be welcomed, it’s certainly not going to quieten the concerns of Pacific leaders who have been very clear that they want Australia to look beyond coal, to move to 100% renewable energy and to really appreciate the sorts of challenges they face here.”

Claire Anterea, co-founder of the Kiribati Climate Action Network, an advocacy group based in Kiribati, which like Tuvalu, is one of the small island states most at risk due to rising sea levels, said: “Our situation in Kiribati and in the Pacific, it’s not about cash, it’s not about giving lots of money, if Australia doesn’t do actions within their own country,” she said.

“Australia needs to do more, not just give money to solve the problem. Money is not the solution for the impacts of climate change. Our Kiribati government is working toward adaptation, but my worry is how long are we going to adapt? Adapt forever? I don’t think that is a possible solution for us, there will be a time when adaptation is not going to work.”