Climate change is expected to bring Tonga serious impacts that include more heavy rainfall events, severe tropical cyclones and extreme sea level events, which will require adaptation for people, infrastructure, and coastal ecosystems4.  Tonga faces a potential long-term threat from permanent inundation and wave-driven flooding, and some studies have suggested that significant displacement of communities will take place (World Bank, 2021a). The largest island Tongatapu, faces significant frequent flooding risks, as well as permanent losses from sea level rise (SLR) in the absence of future adaptation measures. 

Tongatapu is Tonga’s most populous island and has the highest population density holding around 74% of the population (74,320).5 This figure is projected to grow over the next decade with Tongans commonly relocating from the outlying islands to Tongatapu. On Tongatapu there is clear evidence of the impacts of local sea level rise, and the permanent losses under a 0.5m SLR scenario are expected to be 6%, and under a 1.0m SLR scenario to be 25% 6. Sea level rise hotspots present greater impacts in certain areas or regions over others, including the South Pacific Convergence Zone (SPCZ), with greater warming projected in the areas in and around Tonga (the Southwest SPCZ and the Northeast SPCZ)7. By the 2090s, sea level rise is estimated at around 59.5 cm increase using historical records only, or within the range of 40 cm–87 cm under RCP8.5 8. 

By 2150 SLR in Tonga is likely to have risen by 1.37 meters and up to 2m (under SSP3-7.0), and by up to 1m already by 2100.9 With most of Tongatapu’s most populated areas of the north and northeast coasts at only 1m above sea level, SLR is likely to see many settlements inundated in the absence of adequate adaptation strategies in place. Tongatapu faces significant frequent flooding risks, as well as permanent losses from SLR in the absence of future adaptation measures. At the same time, geographic isolation and economic vulnerabilities, including dependence on remittance and foreign aid, increase the challenges faced by communities and decision-makers and compound climate change risks.  

The project therefore seeks to address coastal inundation in critical areas through immediate coastal protection measures in the northeastern parts of Tongatapu, while fostering long term adaptation measures through the provision of critical climate risk information and planning tools supported through key training, knowledge sharing and capacity. 

The project also proposes a transformative adaptation approach through the establishment and support for multi-stakeholder decision making on critical adaptation needs and land use planning. Ongoing climate change threats, risk, and impacts to date have challenged Tonga and brought the issue of transformative adaptation to the forefront. Therefore the overall objective for the project is to support the transformative adaptation agenda setting through a participatory process; supporting development and spatial planning (community development plans, district plans and island strategic plans) to consider climate risks and promote appropriate and transformative adaptation options. Specifically, these are to be achieved through three key outputs:

• Strengthened knowledge, capacity and engagement for incorporating climate risks into long-term adaptation planning supported through multi-sectoral, multi-stakeholder engagement and dialogue platform
• Strengthened national and local capacities for effective monitoring and assessment of climate risks 
• Reduced vulnerabilities of coastal communities in Hahake to climate hazards through coastal protection measures