Complex coastal interactions on Kiribati and South Pacific island affecting growth and viability, including but not limited to climate change

By Magdalena Muir

Broken seawalls, like this one in the Pacific island nation of Kiribati, often have no connection with sea-level rise. Credit: Christopher Pala/IPS

The equatorial Central Pacific is th areas of the world where the sea has risen the fastest since  1950, with a 5.9 centimetre rise in the past 20 years. With the focus on climate change and sea level rise for South Pacific islands, it is important to also consider the other man made and natural forces affecting the islands.  For Kiribati, seawalls and the construction of causeways is causing flooding, in addition to sea level rise. Parts of the islands remain stable, or are growing due to artificial structures building or reclaiming land from the sea.
This is not downplay the impacts of climate change and sea level rise, but to highlight the importance of sound coastal engineering and hard and soft coastal defenses. While sea level rise remains an important long term factor, in some cases, the best immediate response may be greater understanding of coastal dynamics, the impacts of regional and seasonal variations, and  improved coastal engineering and defenses.
The southern part of Tarawa where most of the population lives is growing due to reclamation where dredged sand is place over shallow reefs to create land, increasing the southern region by nearly 20 % over 30 years. In contrast, the northern part of the island has stayed stable. A seawall in Eita in Kiribati was built with dredged sand to protect mangroves, but the seawall was poorly designed and directed the energy of waves so that sand was washed away at the base, causing the seawall to collapse. Bikeman Island disappeared because a causeway was built between two part of an atoll, block the movement of sand from the ocean side. Without this input the sand was washed away from Bikeman to another area of the lagoon that saw their beaches increase. In another area, the village of Tebunginako, an input of sand from the ocean had disappeared over a century, resulting in less sand and greater erosion of beaches.

Other regional forces are also at work. For example, El Nino resulted the sea level to temporarily rise by 15 centimetres in 2005 causing flooding in Kirbati. However this level was caused by El Nino and have not been seen since.

Background information