Green Tau: issue 30

The challenge of rising sea levels for Pacific islands.

20th January 2022

Last week the Green Tau focused on Richmond and the likely effects of the increased risk of flooding arising from climate change. This week the focus will be on Tarawa, one of the 33 atolls that makes up the Pacific nation of Kiribati.  

Tarawa is one of the largest of Kiribati atolls and is home to one 60,000  people, about 53% of the total population. Seen from above, Tarawa is a long thin strip of land that curves to form two sides of a triangle, in the middle of which is a lagoon. (Atolls are islands created by volcanic action. The former crater forms a dip in the middle). The third side of the triangle is below sea level and is home to a coral reef. It has a very long coast line in proportion to its land area. The land is flat and low lying, rising to about 2-3m above sea level.  Beaches on the lagoon side tend to be wider and shallower than this on the ocean side.

Scientific research suggests that the rise in average sea levels for Tarawa, by 2100,  will be between 0.5  (if the global temperature increase is kept below 1.5C) to 1.2m (if the increase in the worst case is 5-6C). Present projections suggest we are on track for a 2.7C temperature rise – and a projected sea level rise for Tarawa of 0.6m. High tide is typically 1.2m above the mean sea level, but is subject to variation. For example tide levels rise during periods when the El Niño weather system is dominant because the high pressure lifts sea levels. Because of its shape, with along coast lines and narrow low lying land mass, Tarawa – like many similar atolls and islands – is very vulnerable to rising seas levels. The people of Tarawa can see that before the end of this century they may no longer have an island on which to live! 

Sea levels also rise markedly when drive by cyclones. The Republic of Kiribati used not to be affected by tropical cyclones but with increasing global temperatures and changing weather patterns, this is no longer so. Not only do cyclones produce flooding with high waves, but the strong winds are particularly destructive to low lying lands such as on Tarawa with the winds breaking sea defences, ripping up vegetation and blowing away soil. (Soil depths are already shallow because these volcanic atolls are relatively youthful in geological terms). 

Tarawa is located on the Equator and it has a tropical rainforest climate. It rains on average every other day, with a high of rainfall of about 300mm a month in January and a minimum of 100mm in September. This ensures that the  water table is regularly topped up.  However the land above sea level at Tarawa is narrow, with saline after on both sides. Rising sea levels leads to the contamination of freshwater supplies with salt. This reduces water for drinking etc as well as damaging agricultural crops and plant life generally. 

Rising global temperature affect not just the air but also ocean temperatures. Since preindustrial times, global sea surface temperatures have risen by 0.7C. The rate of increase has risen in recent decades and particularly so in the last 6 years. Temperatures rises are not uniform and have been more marked in the southern Pacific waters. The IPCC predicts sea temperatures may rise by 1.2 to 3.2C by 2100 (depending on our ability to reduce carbon emissions). Rising sea temperatures affect marine life generally and reefs in particular. Temperature rises in the region of 1C can cause the bleaching of coral reefs. This draining of colour shows that the coral is stressed, and is likely to die.  Associated with heat rises accentuated by El Niño, Tarawa has had repeated incidences of coral bleaching. When coral reefs die and break down, they no longer protect local shores from erosion nor protect lagoons from destructive waves that destroy the particular ecology of those calmer waters. The loss of coral reefs also leads to losses  of  marine biodiversity.

Tarawa and the rest of the atolls in the Republic of Kiribati are not alone in facing these devastating effects of climate change. In 1990 they and other similarly vulnerable countries formed the Alliance of Small Island States to give themselves collectively a more voluble voice in discussion and proposals around the climate crisis. The AOSIS was a particularly strong presence at the Paris Climate Conference in 2015. Their voice was also heard at the Glasgow COP last year although because of covid fewer delegates were able to attend. One of those unable to travel was the former President of Kiribati, Anote Tong. Speaking from home, he told ITV News that beyond 2030 “our very existence might be in jeopardy”. 

In 2012 Tong bought a 2700 hectare estate on the island of Vanue Levu in Fiji as a refuge for the citizens of Kiribati, plus a further 2000 hectares in 2014. Between 2003 and 2015 the Kiribati Adaptation Plan was executed using money raised by the United Nations from wealthy donors such as Australia This included projects such as planting mangrove palms to limit coastal erosion, strengthening sea wall defences, and installing rainwater butts to help safeguard fresh water supplies. 

In 2020 the new President of Kiribati, Taneti Maamau, announced plans, in conjunction with China, to artificially build up parts of Tarawa, to raise them above projected sea level rises.

In the mean time other adaptations projects are on going to improve the islanders’ living standards and build up their resilience in the face of flooding. These include encouraging islanders to develop traditional food gardens to protect against sudden food shortages (much of Kiribati’s food is imported), developing fish management schemes to prevent over fishing, and increasing provision shade to protect people from adverse temperatures. Consideration is now being given to using the land bought in Fiji to provide food for Kiribati. It seems that due to poverty, the people of Kiribati are not well equipped to cope with the extra demands and risks of the climate crisis. Equally important are these projects designed to improve their living standards, health and well being.