Erosion

All of Kiribati is coastal! People in Kiribati are observing extensive coastal erosion taking place, not only of the beach but also of the land, displacing now some of them from their traditional house plots since the early 1900, and felling coconut trees, papaya trees and other varieties of vegetation at the coastal areas. Many of the country’s islands are so narrow that there really is no place to go. Kiribati has roughly 100,000 citizens and its main island, Tarawa, suffers from severe overcrowding.

Although a lot of attention has been given to rising sea levels, this data only tells part of the story. The atolls of Kiribati are experiencing increased wave heights and frequency and we can see that this is placing increased pressure on the shoreline and seawalls. We have observed that storm surges occur far more often than in the past. High waves break over coastal land and seawalls causing flooding and destruction to settled areas and fruit trees. Cyclones and hurricanes occur more frequently in the ocean area surrounding Kiribati and these generate waves that damage the atolls.

Short-term readings of sea level rise are problematic due to large year-to-year variation, in part caused by events such as El Nino (which typically causes a large rise), and La Nina (a smaller rise or decrease). The Australian National Tidal Centre reports that sea levels in Kiribati have averaged a rise of 3.7 millimetres a year since 1992. But incrementally rising seas are only part of the story. Far more damaging are the extreme events that come with them.

In Australia, a 20-centimetre rise is estimated to up the number of extreme seas by a factor of 10. A 50-centimetre rise—now considered a conservative projection for this century unless emissions are curbed – is projected to bring about a 300-fold increase. Oceanographer John Hunter, a sea level researcher from the University of Tasmania, says it is reasonable to think that the impact in the Pacific—where data collection and analysis are under way – will be similar.

What might that mean? According to the same World Bank report, Kiribati’s main island of Tarawa—where nearly half the population lives—will be 25-54 per cent inundated in the south and 55-80 per cent in the north by mid-century due to sea level rise and storm surges unless there is significant adaptation. Factor in what this means for poisoning of groundwater, destruction of limited arable land and spread of disease, and you have an unlivable national capital.

Waves of 5 meters in height have been recorded in the Tarawa atoll and its vicinity. In some parts of Tarawa, ocean wave heights on reaching the beach have been as high as 3.5 meters and waves of this height have been very destructive. The land surface is nowhere any higher than 2-3 meters above the mean sea level.

The science relating to sea level rise has been in a great state of flux. Some long term predictions of sea level rise for Kiribati have suggested that there is a margin of safety present, but this is regularly contradicted by local eye witness observations. For example, in 1997 Kiritimati (Christmas Island) was devastated by an El Niño event that brought heavy rainfall and flooding, resulting in a half-meter rise in sea level. Roughly 40% of the island’s coral died and their 14 million birds, reputed to be among the world’s richest bird population, left the islands. Figures for sea level rise are imprecise and are only indicative of average levels. Isolated extreme climate events on top of sea level rises can be devastating.

“The situation is much more volatile than the data suggests,” says local video producer, Linda Uan. “It doesn’t take into account the other factors such as changing wind directions and storms. Only last month the high tide caused considerable seawall damage on Tarawa, and the levels were much higher than normal – it wasn’t a neap tide and there was almost no wind. We can see these things with our own eyes.”

Other extreme weather events have seemed to increase in intensity. For example, less than a week before the Kyoto Protocol went into effect, Kiribati was ravished by a ‘king tide’—an example of the kind of sea-level rise that is predicted to occur as global temperatures increase. During the king tide many people were affected by waves that reached 2.87 meters, devastating some villages, sweeping farmland out to sea, and contaminating fresh water wells.

Increased flooding has already forced some villagers to move inland, but that this short trip is a temporary solution since we are in danger of falling off if we keep moving back. Land is in short supply, particularly in the capital and urban centre in South Tarawa, which is one of the poorest and most densely populated areas in the Pacific.

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