*5.3. Saltwater Intrusion*

Climate change will have substantial impacts on freshwater aquifers, particularly on low-lying islands in the Pacific [64]. John Walenenea [8], for instance, documents saltwater intrusion in two saltwater communities in Langalanga Lagoon: Busu Island and Radesifolomae. Wells have become unsuitable for drinking as a result of saltwater intrusion, and women now have to paddle considerable distances to collect water during dry periods. But that is only one part of the story: The villages used to have a functional water system, but the dam and the water pipes were vandalized during a land dispute. Similar issues occur in Lau Lagoon, where water pipes that provide water to the artificial islands are occasionally blocked or damaged during land conflicts. Climate change will likely sharpen these social issues [65], but attributing freshwater scarcity on the artificial islands solely to global warming is flawed.

Lilisiana is another interesting case in this respect. This village features prominently in the climate change discourse, and is targeted by a number of CCDRM projects [30]. Lilisiana was built in the 1920s on the outskirts of the newly established government station in Kwaibala, present day Auki town. More saltwater people settled in the village in the aftermath of cyclones in 1952, 1972, and 1986 [29]. At present, Lilisiana is the largest neighborhood of Auki, with approximately 500 inhabitants. Houses are built on the narrow beach and in the mangroves between Osi Lake and Auki Harbour. During cyclones, king tides, and heavy rainfall the village is inundated. Climate change will exacerbate these drainage problems, but is not causing the flooding. The lack of solid waste management facilities and poor urban planning are arguably more proximate causes for the recurrent floods.

In some other cases, the desertion of an artificial island has categorically nothing to do with climate change. Mala'afa Island in Langalanga Lagoon, for example, was abandoned after all members of the land-owning clan died of sickness or committed suicide. People attribute this to sorcery, and think the island is cursed.

#### *5.4. Higher Seawater Temperatures*

To illustrate the climate change impacts on coastal fisheries, the State of the Environment in Oceania report [66] quotes George Alabeni from the Airahu Rural Training Centre in the Solomon Islands:

*"The sea is very hot sometimes and it is not pleasant. Older people have not seen it like this before. The world is changing, everything is changing. Before you just go down to the shore and might take fish and see a lot of seashells, crabs and the beauty of the sea; everything. Good temperature. There are birds all around the beach, very white beach. Now seabirds' coastal homes are being destroyed, and dead fish are washing up on shore. We don't expect it, and it's new to us. We have never seen those things happening."*

Indeed, higher seawater temperatures will negatively impact coastal fisheries through coral bleaching and ocean acidification [67,68]. Compared to other countries in the region, coral bleaching has so far caused limited damage to coral reefs in Solomon Islands [28]. In practice, it is difficult to untangle the multiple stressors of coral reefs and their ability to produce fish. Albert et al. [69], for example, document a large algal bloom in 2011 in Marovo Lagoon in Western Province, which had detrimental impacts on live coral cover and shellfish. But whether this dead zone was caused by increased seawater temperatures, eutrophication due to logging-induced sedimentation, the overharvesting of detrivorous sea cucumbers, or a combination of these factors remains unclear.

The sinking islands of Fanalei and Walande on South Malaita provide another example of the difficulties of disaggregating the multiple stressors of tropical coastal ecosystems in remote, data-scarce areas in the developing world. Geologically, the southeast coast of Malaita is affected by rapid subsidence and earthquakes [70] (see Figure 8). Fanalei Island was heavily impacted by a 7.8 magnitude earthquake in December 2016: A large crack formed and a part of the low-lying island subsided. After this event, tides started to flood the village, and many people relocated to the mainland. Walande Island was largely abandoned in 2017, a process that commenced in 1987 when

the Anglican Church of Melanesia fostered an agreement with wane tolo land owners, built a church, and encouraged the wane asi to settle in the new village [30]. Interestingly, before settling on Walande Island, people lived on Namo Island, which was abandoned in the 1930s after a tsunami (see Figure 9). And in the mythical past, the ancestors of the people of Walande lived on a small off-shore island called Hile, which was, according to oral history, also destroyed by a tsunami (also see Nunn et al. on the disappeared Pororourouhu Islands off the coast of South Malaita [71]). Other coastal areas on Malaita are also subject to geological upheaval: Gold [72], for example, reports that two severe earthquakes in October 1931 destroyed several artificial islands in Bina Harbor in Langalanga Lagoon. In fact, fear for an impending tsunami or cyclone is an important motivation for many wane asi to move from the artificial islands to the mainland.

**Figure 8.** Rapid subsidence on the southeast coast of Malaita (J. van der Ploeg, 2017).

**Figure 9.** Walande Island on South Malaita (J. van der Ploeg, 2018).
