By Angie Knox BBC, Tuvalu

Tuvalu's nine islands are little more than thin ribbon-like atolls scattered in the immensity of the Pacific Ocean.

"Maybe it's to do with that greenhouse effect that's been announced all over the world. But I didn't imagine it would be like this."

At their highest point, they stand no more than four metres (13 feet) above sea level and if predictions of rising sea levels caused by global warming are correct, they could become the world's first casualties of climate change.

That is something that is worrying the country's 11,000 inhabitants.

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Retired sea captain Lotu Pasefika stands in front of his house, knee-deep in water, watching palm fronds and logs drift past in the swirling, muddy floodwaters.

Relentless pounding

Just 30m away, huge ocean breakers crash onto the coral and rock rampart that forms the only barrier between the sea and Tuvalu's main island of Funafuti.

"The first wave broke in when I was down the beach feeding my pigs," he said.

Water has filled the main street

"It came without warning. So I went to alert people. The second wave came in then, and that was the one that brought all the debris ashore."

"We've had high tides before. But this is the first time it's reached my doorstep," he explained, gesturing to the water still flowing down the island's main road.

Seeking shelter

The local people are shaking their heads in bewilderment - it is August, and this is not the right season for such high tides.

"Maybe it's to do with that greenhouse effect that's been announced all over the world," said one woman.

"But I didn't imagine it would be like this," she added.

Tepuka Savilivili has already been reduced to rock

Like her neighbours, she is packing her belongings, ready to decamp to another part of the island for the night. Another high tide is expected, and they have been warned there might be further flooding.

The freak four-metre high waves which hit the tiny Pacific nation of Tuvalu left little behind them except salt-damaged gardens.

But according to Hilia Vavae, director of Tuvalu's Meteorological Service, it is just one more worrying sign of the very real danger Tuvalu faces from rising sea levels.

Disaster threat

Scientists have predicted an 88cm rise in sea levels in the next century - if that is proved correct, Tuvalu, like other low-lying atoll countries in the Pacific Ocean, could find itself underwater within 50 years.

The water strips away the vegetation

That process may already have started. Dotted along the reef that encircles Funafuti's lagoon lie a string of islets. They are popular picnic spots with the locals but they are threatened by erosion.

On a boat trip across the lagoon, Ms Vavae points to what looks like a rocky outcrop, just above the surface of the sea.

"That was the island of Tepuka Savilivili," she explained. "Now you can see all the sand and gravel have been washed away and all that's left is the base of the island."

Local fears

In June 1997, Cyclone Keli dealt the final blow to Tepuka Savilivili, sweeping away the last of the coconut trees and vegetation.

For environmental officer Pepetua, the island is a grim reminder of what fate could await the rest of Tuvalu.

There are fears the children of the islands have no future

"For the future, I'm very worried about beach erosion," she said. "Everyone in Tuvalu can see that problem. It happens on the mainland and on the small islands. So it's most likely that in the future the whole land might be washed away."

Not everyone is so pessimistic. In his traditional garden, behind his house, Kamuta Latasi peeks out from under the huge, elephant-ear-sized leaves of swamp taro, or pulaka.

Plants damaged

To compensate for poor soil, pulaka is grown throughout Tuvalu in pits cut into the limestone base of the atolls.

But it does not tolerate saltwater and in recent years more and more pulaka growers have been noticing that their tubers have been rotting in the ground because seawater has seeped up into the pits.

Kamuta Latasi thinks he has found a solution

Mr Latasi thinks he has found a solution.

"I've cemented the bottom and sides of this pit to prevent the seawater coming up," he explained. "Now, with this kind of method, you can grow pulaka anywhere in the islands."

But given the flooding, erosion and freak waves, perhaps it is not surprising that many of Tuvalu's people are considering leaving.

"I'm worried about the islands," said one woman with tears in her eyes. "This is the best island I know, and I think it's going to end up under the sea. We're thinking of migrating to New Zealand. I don't want my children to see this, it's enough."

Plea to the world

Some, like Mr Pasefika, are determined to stay.

"But to be frank with you, I see no future for my grandchildren. My home is here, but my family, they have to go," he said.

He is very concerned about the changes he has seen in Tuvalu over the years and has a message for the rest of the world.

"People have to stop doing things to damage our environment," he said.

"People must look at us and see us as people who want to lead a normal life, but we cannot lead a normal life because other people are doing what they want for their own development. What about us?"