Salty Water and Sinking Islands

From the ongoing wildfres in Australia to the recent storm Ciara, a climate change-related story hits the news almost every week. Still, there is a distance between those of us in more developed, urban environments and the real efects of the environmental crisis.

For the people of the South Pacifc Islands (PICs), however, it’s a completely diferent story. These people are already feeling the overwhelming efects of manmade climate change and for many they have to look no further than their back gardens to see the frontline of this crisis. These islands may be completely lost within the century and uninhabitable by as early as 2050 and while the changing climate is a real threat to their homes and livelihoods, it also greatly afects their culture, traditions and identity. In some places, sea levels are rising by over 1cm a year (4 times faster than the global mean) and these trends will continue.

Alarmingly, several islands have already disappeared into the sea: 5 uninhabited islands, part of the Solomon Archipelago, along with 3 in the Federate States of Micronesia have been lost in the last decade alone. These unprecedented rises have led to some PICs already starting the process of emigration, an almost certain outcome for their population in the future. Kiribati has recently bought a 20km2 piece of land on Fiji in which to relocate its people when conditions become uninhabitable.

But the South Pacifc is currently facing an even bigger threat- water insecurity and rapidly diminishing fresh water supplies. These challenges have already been exacerbated by population rises on the main islands but are also at a further threat from changing precipitation patterns.

Tuvalu is a small Polynesian island made up of 9 low-lying reef and coral atolls (ring-shaped coral-reef structures encircling a lagoon) with an average height of around 1m above sea level. Along the rims of these atolls are islands composed mainly of coral detritus. They are created as the ring of coral surrounds an underwater volcano that has receded into the ocean leaving the ring of islands behind. This low elevation means Tuvalu is one of the most at-risk countries from anthropogenic climate change. This also means that the increasing frequency and severity of extreme weather events has a real impact on both the island in general and on water security. Rising sea levels have led to a huge increase in urbanisation on the main island as many have been forced to leave their homes on other islands, creating an even greater pressure on already scarce freshwater resources.

Tuvaluans previously relied upon groundwater reserves in aquifer systems (their only natural freshwater source) and the collection of regular rainfall. Aquifers are underground bodies of rock, with varying degrees of permeability and porosity, that are saturated with, and act as underground reservoirs for, groundwater. However, climate change is threatening these systems. Groundwater reserves constitute a signifcant proportion of freshwater in the PICs and even though these are generally recharged by rain, changing weather patterns may lead to a reduced recharge rate, further diminishing water resources on the islands. In the future, climate projections show that there will be much greater variation in rainfall from year to year, creating more insecurity in terms of water resources. Although mean rainfall may increase slightly in some areas of the Pacifc islands, including Tuvalu, so will the instances of drought and extreme drought. Rising sea levels have led to salt-water intrusion and contamination of these groundwater systems, meaning they are no longer suitable for either drinking or agriculture. Water tanks are a common site in Tuvalu, meant to meet the water needs of large households, especially on Funafuti- now home to almost half of the nation’s population.

The Pacifc Islands are also particularly vulnerable to extreme weather events, mostly tropical cyclones and storms. In the last 30 years, Vanuatu (a mountainous archipelago in the Melanesia region) has experienced a total of 72 tropical cyclones (the most out of all the PICs), the biggest of which was cyclone Pam in 2015, which caused huge devastation to the islands and amounted to a loss of around 65% of their GDP. Research has shown that, although the number of these tropical cyclones will not go up, the proportion of more intense storms will, with wind speeds increasing by up to 10%.

The conclusion for the future of these islands and ultimately of our planet can be summed up in the words of the current Secretary-General of the UN, Antonio Guterres: “Urgent climate action is a choice we canand must-make. As the people of Tuvalu know all too well: Saving them will save us all”. Taras Bains is a Biological Sciences undergraduate at Wadham College.