Down the only road that runs the length of the island. Past the dump, with its rusting skeletons of cars and heaps of fetid household refuse. Through the jungle of towering coconut trees. Along the talcum-powder beach, beyond the point at which it gives way to shattered rocks and bleached coral. That is where the concrete sentinel stands. Out alone in the sea, it keeps a silent vigil, waiting for the end of the world as they know it to arrive in Tuvalu.

This ziggurat – that now stands surrounded by surf several metres from the end of the islet – was built by the United States military during the second world war. It served as the pedestal for a large anti-aircraft gun, says Emilio Eliapo, a 24-year-old local. Once the conflict in the Pacific had come to a bloody close, the Americans removed the gun but left the concrete base standing. Over time, the ground disappeared beneath it, as erosion nibbled away at the shore and the sea rose up.

“When I was little, that used to be in the jungle, just like over there,” Eliapo says, pointing towards a mesh of trees back along the coastline that would have provided natural cover for an anti-aircraft position.

“The only thing we have here in Tuvalu is to pray. We are a very small island and very poor. We can’t go and buy more land.

“Climate change,” he says with a sigh.

Tuvalu is one of the most isolated countries on the planet, with two small propeller planes flying weekly from neighbouring Fiji providing its only air bridge to the world. It did not have television until 10 years ago, and it still lacks a hard-wired, underwater-cable internet connection.

But few other countries are as close to the front line of the battle against climate change as Tuvalu, a cluster of nine tiny islands and coral atolls tucked away in a remote corner of the South Pacific. The main atoll and largest population centre, Funafuti, appears from the air as an apparition: a spectral ring of thin jungle and dazzling white sand wrapped around a deep azure lagoon and nothing more. Half the country’s minuscule population ( just over 10,500) live here, despite the main islet being less than 500 metres wide at its broadest point and just two metres above sea level. The atoll is so low that in places it tricks the eye into thinking you’re looking up, rather than down, at the surrounding ocean.

The sea level here is rising by about 5mm annually. The US National Research Council (NRC) predicts global sea levels could rise by as much as 140cm by 2100, as developing economies such as India and China pump ever greater amounts of carbon dioxide into the atmosphere.

Combine that stunning projection with the challenges of seawater acidification and climbing overall temperatures, and one starts to get a sense of just how perilous the situation is for Tuvalu – much of the country will be under water by the end of the century if the NRC figure is correct. And that is before you factor in the population pressures that have pushed people to build stilt homes atop open rubbish dumps, on what are often the only unclaimed parcels of land on Funafuti.

Climate scientists have labelled Tuvalu the canary in the climate-change coalmine. Together with the similarly challenged nearby Kiribati and the Maldives, it could come to show what coastal areas from Manhattan to Shanghai will face in coming decades.

Progress will be slow but inexorable. Eventually, the ocean will swallow up the land.

“If anything, the threat posed by sea-level rise will be death by a thousand cuts,” says James Conway, a 53-yearold American adviser to the government of Tuvalu, who is married to a Tuvaluan woman. “Unless Tuvaluans adopt the lifestyle of the Marsh Arabs and build their houses on stilts over water, and that’s where they live 24 hours a day, eventually most, if not all, of the island will become uninhabitable.”

It is a typical Sunday morning on Funafuti, and the scorching tropical sun is giving ground to looming black clouds pregnant with a deluge that will quickly transform the roads around the Church of Tuvalu into a soup of mud and rubbish.

Children traipse through the slurry in their Sunday best, trying to stave off boredom. From inside the building, one of the few truly modern structures on the impoverished island, the sweet strains of hymns waft out as the deeply religious Tuvaluans come together for their weekly prayer.

A hand-carved sign above the church door reads, “Fetu Ao Lima”, which a hip young islander sporting aviator glasses tells me means, “Put your hands together in prayer”. Inside, rows of ceiling fans cool the steamy room as a stern young man dressed in an impossibly white suit preaches to upwards of 1,000 people. There are so many people here, in fact, that they occupy every available space. Thick crossbeams hold up the high vaulted roof and as the choirmaster coaxes fresh melodies from his charges, their voices again rise to the rafters in ecstatic praise.

After the sermon has finished and the crowd has mostly dispersed to spend the rest of the day within the tightly knit family units that form the cornerstone of society here, I head off in search of the young preacher to ask what God thinks about global warming. Reverend Tanei Letueti, a stocky 31-year-old part-time reverend and full-time shopowner, is sheltering from the rain in the porch of a modest house behind the church.

“If God’s will is for the island to sink, then it will sink.

But it’s not the end of the world, because God already has a plan for us, like migrating to other places,” he says with an unconvincing smile.

As we move inside to the small kitchen, Letueti grows more pensive. He has reached the same conclusion as many young people: that they will eventually have to leave their homeland to its fate. The elderly members of his parish, however, really worry him.

“The old people, they find it hard to migrate,” Letueti says. “The pace of life in other countries is too much; it’s too fast for them. Old people say they will sink with the island.”

Tuvalu’s government, whose handful of ministers spend several months of the year travelling to environmental conferences, seems never to tire of presenting its case to the international community. In 2003, then Tuvaluan prime minister Saufatu Sopoanga made a speech to the United Nations General Assembly in which he called climate change “a slow and insidious form of terrorism against us”. But talk has done little to accelerate global action on climate change and Tuvalu’s peril often seems to be out of sight, out of mind.

Just down the road from the church – everything in Funafuti is essentially down the road from everything else – is Nauri Primary School. Children are much easier to frighten than their parents, many of whom try to put a brave face on the challenges, says the 49-year-old head teacher, Betty Vuva.

“We ask them about the future and where they would like to be, and most of them say they’d like to migrate to New Zealand or Fiji,” she says. “One of the kids asked me, ‘Can’t we just make the island taller?’” The Maldives, a cluster of tropical islands in the Indian Ocean, and Kiribati, which was part of the Gilbert Islands with Tuvalu until its independence from Britain in 1979, are both low-lying island countries facing imminent danger from rising sea levels. Both have stepped up international lobbying in recent years in an attempt to force action on climate change, but have largely failed to achieve Tuvalu’s prominence.

“Tuvalu just got on it very early and has been talking about being an advocate about climate change and sealevel rise since the late 1980s and early 90s,” Conway says. “It’s been able to position itself internationally as uniquely threatened, let’s say, by sea-level rise, the loss of land, the loss of culture, the loss of sovereignty, the loss of state. In effect, it’s put Tuvalu on the map, figuratively speaking.”
The sheer determination of its leaders seems to be Reverend Tanei Letueti. the driving factor behind its public-relations successes, but one would be misguided to play down the perfect storm of pressures Tuvalu is facing.

Erosion, rising sea levels, acidification of the oceans and the destruction of coral reefs that results from it, population pressures, less frequent but more violent weather events such as tropical cyclones, and climbing temperatures that are producing more scorching-hot days than ever in its history are just the most prominent of Tuvalu’s climate-change problems, says Kathleen McInnes, a Melbourne-based climate scientist.

“The analogy of death by a thousand cuts is quite accurate, I think, because it’ll be a whole combination of things; it’ll be the fact that they can’t grow their crops and that there are too many people and so on,” she says.

Last year, punishing droughts led the Tuvalu government to declare a state of emergency, which was only removed after the New Zealand Defence Force flew in drinking water and a portable desalination plant. Almost every home on Funafuti now has at least one 10,000-litre plastic tank to capture rainwater, and many have more than that. Cargo ships at the loading dock can be seen daily loading more tanks onto boats headed for the outer islands.

Perhaps the most insidious aspect for Tuvalu, though, is the impact of acidification on the country’s coral reefs.

There is little arable land on Funafuti, and the vast majority of protein in the islanders’ diet comes from reef fish that are easier and less expensive to catch than the large stocks of tuna further out to sea (these are trawled by larger ships for export). About one quarter of the CO2 emissions from human activities each year are absorbed by the oceans, and as the extra CO2 reacts with seawater, it causes the ocean to become slightly more acidic.

The impact of this acidification on the health of reef ecosystems – compounded by other factors including coral bleaching and storm damage – is bad news if you happen to live on fish that live in the coral.

However, soon none of that will matter if the ocean continues to rise at the rate predicted by scientists.

“It’s a matter of whether the resilience of the reef can keep pace with the rate of sea-level rise, and we just don’t know that,” says McInnes. “We can learn a lot from these smaller islands in terms of how they face these changes.”

Still, she says, it would be infinitely better if the lesson in climate change from Tuvalu did not imply the worst for the people who call it home.

FUNAFUTI IS ITSELF a coral atoll, which means that water seeps up through the porous rock surface at high tide, filling any holes in the ground with bubbling seawater.

It is high tide now, and I am standing over part of the other major wartime legacy left by the Americans.

In addition to the anti-aircraft gun, they left a series of what are called “borrow pits” across the island – troughs from which coral was extracted during the war to pave the island’s only runway.

Over time, as land has become more scarce, locals, such as 27-year-old mother Ravina Falemi, have built houses on top of the borrow pits. The pits have, in turn, been filled with a mixture of household and animal waste that, at high tide, becomes pools of rancid water in which local children play to escape the punishing heat. The stench is appalling, although one child fishing in the brackish water for small fish seems not to mind.

When asked whether she is worried about the health risks for the swarms of children playing in the pits, Falemi, who is standing with a young child clamped around her waist, says she is. But when asked whether that is her biggest fear for her children, she shakes her head and points towards the sea just metres away.

“Especially at the time of the tsunami. No mountains.

No higher place we can go,” she says in halting English.

Not only is there no place to go on the island, few destinations overseas are willing to take Tuvaluan migrants. New Zealand accepts about 75 people a year and has ultimately committed to absorbing its population in the face of total annihilation while Australia has refused to initiate its own resettlement policy.

But at what point is all considered lost? Which of the thousand cuts will be considered fatal and who will make that call?

Ultimately, everyone here seems to agree that it is a matter of when, not if, Tuvalu will become the first nation to disappear as a result of climate change. And for Eliapo, standing by the makeshift seawall he has built on the lagoon-facing side of his home, that means nothing less than the death of a way of life.

“Nothing bad happens here,” he says. “It’s not like other places, where somebody might rob your home or other bad stuff. It’s like a heaven: you can sleep outside and nothing bad happens.

“We have lots of fun here, not like those other [countries] like Libya, where they are always fighting Sunday afternoon on Funafuti. and stuff.”