Sydney to Hawaii

During El Niño, warm surface water collects in the east and central Pacific, causing unusually wet weather in places that would ordinarily be drier.

During La Niña, cold currents rise towards the surface in the East Pacific, with warmer surface currents pushing west and bring rain to the western Pacific.

Two diagrams showing the difference between ocean current flows and their effects on weather conditions during normal conditions and El Niño.

Two diagrams showing the difference between ocean current flows and their effects on weather conditions during normal conditions and La Niña.

Graph showing global temperature anomalies since 1950, suggesting a clear increase in temperatures caused by El Niño and La Niña in the last three decades.

Satellite image showing the Pacific during the 1997 El Niño. Purple indicates reduced sea level (in the region of Tuvalu) , and white indicates increased sea level. During La Niña, this pattern is reversed.

Map showing sea surface temperatures during La Niña. The blue across the mid-Pacific indicates below-average sea temperatures that bring drought to Tuvalu.

Diagram showing the global changes in weather during El Niño. Tuvalu is located in the mid-Pacific, and is one of the few places to receive wet weather during El Niño.

Diagram showing the global changes in weather during La Niña. During this time, Tuvalu is located in a dry region, which brings drought to these isolated islands.

One of the tiny islands that make up Tuvalu. Rising sea levels have already claimed the shallow beaches surrounding this island, as sea levels have risen by 5mm a year for the last two decades.

Tuvalu is the fourth smallest country in the world by land area, made up of just four coral islands and five atolls.

Tuvalu's islands are spread across a large area of the Pacific. It is predicted that these islands could be almost entirely submerged by the end of the 21st century if sea levels continue to rise.

Protesters at the 2009 Copenhagen Climate Change Conference. Tuvalu stalled talks at here under concerns that participating nations were not committing fully to reducing carbon emissions.

For people in Tuvalu, even everyday tasks like washing clothes may become increasingly difficult due to rising sea levels resulting in a lack of fresh water on the islands.

From the air, it is clear to see how flat and exposed Tuvalu's islands are and why they are so vulnerable to changes in climate and sea level.

As sea levels have risen, Tuvalu's population have been forced to adapt to the changing environment. Here, houses are elevated on stilts to avoid flooding.

Pollution from a growing population combined with rising sea levels have tainted Tuvalu's ground water, leaving inhabitants reliant on rainfall for their fresh water supply.

Tuvalu has already begun to install tide blocks in order to keep back the rising sea.

Funafuti is Tuvalu's main island. On average, this long thin strip of land is about two metres above sea level, making it at risk from rising sea levels.

Tuvalu's Government Building overlooks the water. As sea levels continue to rise, more and more of Tuvalu's land will be lost to the sea.

The powerful tides of the Pacific Ocean batter the exposed shores of Tuvalu's largest island, Funafuti.

Tuvalu is almost completely flat, putting it at risk of being submerged with high tides or rising sea levels.

Map showing the migration patterns of Polynesian and Melanesian people throughout the Pacific. The discovery at Nanumanga Cave in Tuvalu, however, calls this timeline into question.

1824 - Illustration of Polynesian men on a sail canoe. This was the way that early Polynesians travelled across the Pacific.

1841 - Illustration of a traditional Tuvaulan. The evidence found at Nanumanga Cave suggests that people lived on these islands more than 8,000 years ago.

Location of Tuvalu in the Pacific. Evidence of human life in the Pacific earlier than 8,000 years ago has been found here, 2,000 years earlier than previously thought.

1842 - Painting of a Polynesian sailed canoe. It is thought that Polynesian people migrated across the Pacific in canoes such as these.

1773 - Depiction of Tongan canoes with sails. Polynesians would have travelled in crafts such as these to colonise the disparate Pacific Islands.

The location of Nanumanga on a map of Tuvalu. It was off the coast of this island that divers discovered a cave with fire markings inside, 40 metres below sea level.

Traditional canoe carving is still practised on Tuvalu. Early settlers on Tuvalu were thought to have arrived by canoe across the Pacific.

Satellite image of Nanumanga Island, where the underwater cave was found with evidence of ancient human habitation.