Sea levels are rising because of climate change. Rising sea level is a serious concern for those countries with low-lying coasts. It is also a major threat to small island states (SIDS).
The threats posed to SIDS in the south Pacific.
These states, particularly those partly or wholly composed of low-elevation coral islands, are facing threats including:
· land areas may become flooded and/or made uninhabitable.
· valuable coastal ecosystems such as corals and mangroves may be overwhelmed.
· the coasts from which maritime claims are measured may retreat (leading to a loss of rights to ocean space and access to valuable resources).
· they may become entirely submerged which could lead to a loss of statehood.
The south Pacific region contains 12 independent states (Micronesia, Fiji, Kiribati, Marshall Islands, Nauru, Palau, Papua New Guinea, Samoa, Solomon Islands, Tonga, Tuvalu, and Vanuatu), and three linked with New Zealand (Cook Islands, Niue, and Tokelau). There are also several territories dependent on, or associated with, former colonial powers such as France (French Polynesia, New Caledonia, Wallis, and Futuna), the UK (Pitcairn Islands), and the USA (American Samoa, Guam, and Northern Mariana Islands).
Collectively, the Pacific islands total just over 500,000 km2 of land, with Papua New Guinea accounting for 84% of this area. These countries claim large maritime spaces off their coasts, including exclusive economic zone (EEZ) claims out to 200 nautical miles from baselines along the coast, in line with the United Nations Convention on the Law of the Sea (UNCLOS). These countries and territories have maritime claims over at least 30 million km2 of the Pacific Ocean. They contain valuable marine resources, especially fisheries. For example, the south Pacific region contains the world’s largest tuna fishery.
Rising waters
Low-lying small-island states face the threat of being inundated by sea-level rise. Their entire land territory could be rendered uninhabitable - by flooding, saline contamination of water supplies or extreme weather events. Total inundation would make a country’s statehood legally questionable, as one of the requirements for statehood is possession of a permanent population and a defined territory.
However, this is not likely in the immediate future. IPCC projections suggest up to a 98 cm sea-level rise by 2100. The impacts of this would be devastating, but no state would be completely inundated. Even higher-elevation islands would be seriously impacted because most of their population and infrastructure is concentrated on the coast, which is often protected by vulnerable fringing reefs.
The maritime zones that coastal states have claimed are also under threat from sea-level rise. Claims over maritime spaces depend on the location of ‘baselines’ along the coast which usually coincide with the low-water line. However, although coastlines are dynamic and change location regularly over time, global sea-level rise has the potential to change coastlines rapidly and substantially. Even a moderate vertical increase in water levels can produce dramatic changes in the location of a coastline laterally.
It is understood that ‘normal’ baselines along the low-water line can change position over time, and the outer limits of national maritime claims may therefore also change. Sea-level rise has the potential to reduce the areas of maritime claims and thus the rights over the resources, such as tuna stocks, within them. So, as the coastline moves inland, the maritime territory will decrease in size.
Pressure
The Pacific SIDS are among the states that have done the least to cause climate change and yet are on the front line of its impacts. They have put pressure on the global political community to act – they campaigned for a lower temperature target in the 2015 Paris Agreement. As a result, the agreement calls for the increase in global average temperature to be kept well below 2°C above pre-industrial levels - with efforts to limit the increase to 1.5°C to reduce the risks and impacts of climate change. Unfortunately, even if the 1.5 goal is achieved, substantial sea-level rise appears to be ‘locked in’ for the foreseeable future.
Coral reefs
Corals can respond to changing sea levels. They can gain elevation and provide sediments that allow islands to build up on reefs. Coral reefs and islands can be remarkably stable and adapt naturally to sea-level rise over time. But it is not clear whether this natural adaptation to changing sea level can keep pace with rapid sea-level rise, especially as oceans are not only warming but also acidifying and de-oxygenating which impairs the ability of reefs to grow. The IPCC predicts a ‘further loss of 90% of reef-building corals compared to today’, with losses of 99% of coral reefs if the world warms by 2°C.
Governance
One response is for the Pacific Island states to assert the extent of their maritime claims. As a strategic priority under their regional oceans governance framework called the Pacific Oceanscape, Pacific Island states have been actively delimiting their maritime boundaries to ensure the impact of climate change and sea-level rise does not result in reduced jurisdiction of the SIDS. The purpose of this exercise is for these states to retain their claims over their existing maritime entitlements, including their rights over the fisheries resources within their maritime zones.
This would mean that some of the countries that have contributed the least to climate change through greenhouse-gas emissions would have their maritime rights and marine resources safeguarded against an uncertain future.