Prime Minister Scott Morrison will touch down in Tuvalu, one of the smallest and least-visited nations on Earth, for the annual gathering of Pacific leaders who have named climate change as their top issue.

Key points: Tuvalu is made up of nine atolls with a combined land area of just 26 square kilometres

Tuvalu is made up of nine atolls with a combined land area of just 26 square kilometres The tiny nation is said to be on the "extreme frontlines of the global climate emergency"

The tiny nation is said to be on the "extreme frontlines of the global climate emergency" It is one of six Pacific countries that still has diplomatic ties with Taiwan

But this year's Pacific Island Forum (PIF) poses some logistical challenges as Tuvalu's capital Funafuti — a Pacific atoll not even half the size of Melbourne's CBD — absorbs the summit's 600 visitors among its humble 6,000-strong population.

Mr Morrison will join leaders from 17 other countries including New Zealand, as well as representatives from China and the United States.

Delegates and officials are reportedly being housed in demountable buildings along the length of the island's airport runway, which take up a large chunk of usable land, while other attendees including media are staying in prefabricated housing.

Like most of the Pacific, Tuvalu — which sits halfway between Australia and Hawaii — is on the frontlines of climate change and this week's summit is set to put Mr Morrison's pledge to "step up" in the Pacific to the test.

To put their money where their mouth is, the forum is advertised as a paperless and plastic-free affair with all of the summit's documents being distributed on USBs as delegates are advised to bring along reusable water bottles and thermos — including Mr Morrison.

The summit — which kicked off yesterday ahead of Mr Morrison's visit — is already shaping up to look like a tough facing off between Pacific leaders, China and Australia who are set to discuss climate change surrounded by little but the vast Pacific Ocean.

Here's a look at the 2019 PIF host nation, the disparity between its relationship to rising sea levels in comparison to Australia's, and how China might fit into this week's jamboree.

First of all — where exactly is Tuvalu in relation to Australia?

Map Tuvalu is north-east of Australia

Tuvalu, previously known as the Ellice Islands, is a clutch of nine islands in the South Pacific about 4,000km north-east of Sydney.

As a former British colony, many speak English as well as the local Tuvaluan language.

With a combined land area of just 26 square kilometres and its highest point above sea level at roughly 4.5 metres, it's the fourth-smallest state in the world, only larger than its neighbour Nauru, Monaco and the Vatican — for comparison, Australia is some 7.7 million square kilometres with a point above sea level of 2,230 metres.

Only main island Funafuti has an airport with only three commercial flights to the country a week.

An aerial view of Funafuti, the largest atoll in Tuvalu. ( Google Earth Studio )

But despite the atoll's postcard-perfect views, the most recent data from the United Nations World Tourism Organisation shows a mere 2,000 international tourists visited Tuvalu in 2017 compared with more than 8 million who visited Australia.

Tuvalu has the smallest gross domestic product (GDP) of any sovereign nation in the world — at just $US42.6 million ($63 million) in 2018 — and has limited ways to generate income.

Media covering this year's Pacific Islands Forum are staying in prefabricated housing. ( ABC News: Melissa Clarke )

The Independent reported the island nation once made millions from telephone sex lines, routed through the country's international access code, 688, but the contract was cancelled in 2000 because of the Christian population's disapproval of the arrangement.

In the late 1990s, Tuvalu also famously sold its internet suffix .tv for $US50 million ($74 million) to a Canadian company DotTV, who acquired the rights sell the suffix on to broadcast companies like Twitch.tv and Pedestrian.tv for 12 years.

Other streams of revenue include the sale of fishing licences and postage stamps.

Tuvalu also has no supply of safe freshwater, and has previously declared a state of emergency because of a severe shortage.

Why Tuvalu is the poster child of climate change

Children play in the waters of Tuvalu's biggest atoll, Funafuti. ( ABC News: Melissa Clarke )

The Pacific nation is often cited in discussions about climate change and rising seas, given the country's 4.5-metre high point and average elevation of less than 2 metres.

During a recent trip to the South Pacific in May, UN Secretary-General Antonio Guterres declared Tuvalu to be "on the extreme frontlines of the global climate emergency".

"Rising seas threaten to drown this island nation — a sign of what's in store for us all," he tweeted.

"We need urgent climate action to stop Tuvalu from sinking and the world from sinking with it."

In the face of rising sea levels, the island nation reportedly has grand plans to build a man-made island complete with a runway and port, and make it large enough to house 5,000 people.

But the island comes with a hefty price tag of some $300 million, and is more likely to be an aspiration for Tuvalu because of its humble GDP.

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While Mr Morrison has pledged $500 million earlier this week to help Pacific nations invest in renewable energy and "climate and disaster resilience" over the next five years, the money will be redirected from existing aid programs rather than being additional support.

Tuvalu's Prime Minister Enele Sopoaga has also warned that the climate money should not be used by Australia as an excuse to avoid reducing emissions and phasing out coal-fired power generation.

Jonathan Pryke, director of Pacific Islands Program at Lowy Institute, told the ABC that Pacific leaders wanted to see Australia take action on its own domestic energy policy and he did not expect to see any "dramatic" changes being announced at PIF.

"There's a lot of ways in which [Australia] would try to spin it to argue that we do a lot of work in this space, but it's really going to fall on deaf ears in the region that really wants to see changes to our domestic policies," he said.

"What [Mr Morrison's] prepared for, is to be the bad guy at PIF and just weather that storm and keep moving.

"So credit to Scott Morrison for going, if I were him I would not be looking forward to it.

"He's made his commitment, that to step up you have to show up, and he's following through on that."

If sea levels continue to rise, the Pacific's food plantations may risk being destroyed due to saltwater intrusion. ( Oxfam: Rodney Dekker )

George Carter, a research fellow at the Department of Pacific Affairs at the Australian National University, told the ABC climate change posed a significant challenge to the environment, livelihood and culture of the people on Tuvalu.

Dr Carter, who is currently in Tuvalu for PIF, said the erosion of coastal land, where seawater had eaten away land for homes and agriculture, was a key concern for the Government.

Ocean acidification had also destroyed many coral reefs, he said, which has led to the migration of fish, impacting both subsistence fishing and deep-sea fishing — "a million-dollar industry" that has been "a lifeline to the people of Tuvalu".

"[There will be] changing and more extreme [weather] patterns — the atoll nation has and will continue to face more and more droughts, storm surges, cyclones and severe rainfall," he said.

How Beijing's pressures might galvanise the remote summit

This year marks the 40th anniversary of diplomatic ties between Taiwan and Tuvalu. ( ABC )

Tuvalu is one of Taiwan's 17 remaining allies worldwide — and this year marks the 40th anniversary of their diplomatic ties.

But their relationship could face renewed pressure as China pursues closer ties with countries across the Pacific and around the world.

Beijing has been known to put pressure on countries who side with Taiwan, for example, a ban on Chinese tourists to Palau last year left hotels empty and an airline in limbo.

But the Solomon Islands, the largest among the six Pacific nations which still support Taiwan, is reconsidering its position.

"In the last 15 years, as Solomon Islands has remained an ally of Taiwan, their economic relationship has gone more and more with mainland China," Mr Pryke told the ABC.

"That still continues to be a very live debate in Solomon Islands, it seems like there may be a swap happening sometime soon."

Mr Pryke added Tuvalu was much smaller and therefore "can be swayed by personality politics and by the political elite".

"I wouldn't be surprised if China were trying to work behind the scenes to try and make a swap happen, but a lot of this calculation does become financial in terms of what kind of benefits the country itself gets," he said.