Tuvalu is a tiny set of nine islands (atolls and reefs) in the South Pacific. They are low-lying with no point on the islands being higher than 4.6 metres above sea level. They cover just 26 square kilometres (10 square miles), making them the forth smallest nation in the world. In 1978 the islands became independent from the UK.
The islands have no natural water features and so have to harvest rainfall to provide a supply of potable water. Most food is imported and, economically, the islands are resource poor. There is a reliance on aid. Copra, a dried coconut kernel, is really the only export commodity to speak of. Salinisation is affecting the growing of crops as the soil becomes more and more unworkable. An interesting “export” is the sale of the internet domain suffix: “.tv”. This has been sold to provide an income by re-selling it around the world to television stations.
The low-lying geography of the islands has caused some problems: they are at great risk from tropical cyclones and the rising sea levels caused by climate change. Additionally the islands are under threat from the perigean tides. The perigean spring tide occurs three or four times a year when the Moon’s perigee, the closest point to Earth during its 28-day orbit, coincides with a spring tide. Spring tides occur twice a month when the sun, moon and earth are in alignment (associated with a new and full moon phase).
Rising sea levels are affecting this island already and there is a prediction that the sea levels may rise by up to a half a metre over the next century. See this Australian Bureau of Meteorology 2010 report. The Bureau of Meteorology reports says that the rising trend is typically in the region of +3.7 to +4 mm each year. The situation is very complex to assess as the sea level is affected by many factors such as the moon, tsunamis, tropical cyclones and even periodic El Niño events. There is a pronounced seasonal cycle of tides that flood Funafuti (an atoll where Tuvalu’s capital is located).
One of the interesting facts is that the land is not receding as may have been expected from a change in the sea level. This is confirmed in this study which note that because the islands are so low lying, waves will crash over them, often adding more sediment to them. This builds up the land height and area. As a result the islands are actually not experiencing a loss in area that may be expected with the sea level changes. This further complicates the picture of climatic changes on Tuvalu’s islands.
Certainly some people are leaving Tuvalu for other places as indicated in this Frontline report. Several people have left for New Zealand from the country. Their “numbers are minuscule” according to this article. The people leaving may be doing so for more economic than climatic reasons.
Another nation that could well be affected by the rising tides is the Maldives that are generally lower lying than Tuvalu. Tuvalu shows that rising sea levels are complicated, they have many other triggers other than climate change per se, although climatic changes may contribute to more cyclones and storms. The salinisation of the ground appears to be getting worse meaning that what does grow here is going to be impeded in the future making it more difficult to survive on agriculture for example. Clearly Tuvalu’s long term sustainability is affected by economic as well as climatic factors.