Drought Early Warning Systems for Disaster Risk Reduction in Pacific Island Countries

Droughts can profoundly affect the livelihoods, economies, ecosystems, and cultural vitality of Pacific Island communities. Despite being one of the costliest hazards in the region, drought remains difficult to predict and communicate due to its slow-onset and multifaceted nature. These complexities are further heightened in the south-west Pacific, as small land areas, sparse observation networks, and high exposure and vulnerability contribute to a largely reactive drought management landscape in which droughts often reach peak intensity, affecting millions before interventions are initiated.This thesis examines proactive approaches to drought management in Pacific Island communities by applying a novel framework for drought early warning, wherein concern is categorised through combining historical drought observations with forecasted drought conditions. In this way, drought concern is highest when antecedent conditions are drier than average and anticipated conditions from seasonal forecasts indicate a high likelihood of persistence. This concept can enable decision-makers to approach drought with a more preparatory management style that favours prompt, early action over reactive, late stage decision making.This framework is first applied to the Pacific Island country of Papua New Guinea (PNG), where a severe drought in 2015 culminated in widespread famine and loss of life. This event and its aftermath generated a strong drive to advance PNG National Weather Service's capacity for a Drought Early Warning System (DEWS). In close collaboration with local staff and system users, a DEWS was designed, tested, and implemented, and is now operational and distributed to national and provincial stakeholders. To expand on this application, DEWS concepts were deepened through implementation in a data-rich domain like Australia. This extension allowed for a more sophisticated, multivariate delivery of a DEWS, similar in style to the United States Drought Monitor with the added utility of coupled seasonal forecasts. From this application, and following a thorough examination of appropriate satellite soil moisture products, the DEWS concepts explored for PNG and Australia were then applied to smaller island nations with the added exploration of longer-term shifts in future regional rainfall using dynamically downscaled projections datasets. The results of these applications provide a foundation for the concept of a ‘window of action’ between a drought early warning and the peak of the associated event, creating practical lead time for early intervention and opportunities to mitigate impacts before peak conditions. This research shows that windows of three to five months are possible across the study domain, during which decision-makers can equip vulnerable communities with resources, encourage strategic sectoral action, and enable safe movement in the regions expected to be hit hardest.The main finding of this thesis is that small island domains (long neglected in early warning research) can benefit from the combined application of high-resolution satellite monitoring products with low-latency seasonal forecasting datasets to provide early warning of drought. When further contextualised by longer-term projected rainfall decreases of up to 15% in annual, wet-, and dry-season rainfall for some islands, such proactive and context-specific approaches to drought will be crucial for long-term adaptation and response. Pacific Island communities have faced and responded to drought several times throughout history, with a rich cultural and ecological understanding fostered within their networks. We note the importance of coupling DEWS outputs with these traditional knowledge systems to enhance trust and usability of early warnings. As climate change intensifies and the resilience of small island communities is further strained by increasingly frequent and extreme events that compound existing vulnerabilities, such proactive management will be essential in safeguarding the vitality of local ecosystems and the communities that live in symbiosis with them.