Port Vila faces extensive environmental threats, evident in its recent ranking as the “world’s most exposed city to natural disasters.” (Verisk Maplecroft (2015), Natural Hazards Risk Atlas). Such environmental threats, many of which are linked to the impacts of climate change, are exacerbated by existence of impoverished people, limited economic opportunity, and tenuous connectivity to external markets.
Due to its geographical, climatic, and spatial context—the city is located within the South Pacific Convergence Zone (SPCZ), placing it within the Pacific cyclone belt and on a very active tectonic plate boundary, and it is also part of the ‘Ring of Fire’, a chain of volcanoes that are located on the edge of the Pacific Plate–Port Vila is exposed to a variety of natural hazards of varying severity. These environmental hazards include, but are not limited to, cyclones/tropical storms, earthquakes, tsunamis, localized flooding, landslides, sea level rise, extreme heat and drought.
While Port Vila has long been exposed to natural shocks, its continued growth, industrialization, and urbanization, coupled with climate-related increases in hazard intensity, has resulted in devastating events. A strong offshore earthquake caused widespread damage to the town and surrounding area in January and in March 2015 Tropical Cyclone Pam, the most powerful cyclone ever recorded to make landfall in Vanuatu, devastated the town once again – with 90 percent of all buildings in Port Vila damaged or destroyed, and left nearly 30 percent of the country’s population homeless, also decimating nearly 90 percent of all subsistence crops, on which a large proportion of the population depends.
Based on the analyses conducted by international actors working on resilience in Port Vila, it is possible to identify two main, interconnected strands of urban challenges. One challenge relates to the extensive variety and magnitude of environmental threats, coupled with, and exacerbated by, the contingent impacts of climate change. The other is derived from the degree to which the city remains simultaneously isolated from, and dependent on, external markets; structural vulnerabilities that are compounded by continued economic transition away from subsistence-based agricultural activities and towards low-value export products and tourism.
The two strands of challenges are categorised below into three environmental threats and one, multifaceted economic/social threat. It should be noted that these threats often overlap and/or compound one another, as was the case in 2015 when Tropical Cyclone Pam was preceded by a mere two weeks by both a volcanic eruption and an earthquake.
Earthquakes, and volcanic activity. The Vanuatu archipelago is located within the New Hebrides Subduction Zone where the Australian and Pacific Plates overlap. Volcanic activity is also present in the area, which can also trigger tsunami wave action events. Seismic events are often connected to liquefaction and landslides. Small seismic events are commonly recorded in Port Vila with larger events having occurred every 5-10 years over the past quarter century.
Extreme rainfall and flash flooding. Flash flooding around Port Vila is predominantly driven by lack of effective drainage, localised flooding can occur even with average rainfall, and is not restricted to severe storm events of prolonged wet periods. However, there is a high frequency and intensity of extreme 1-in-20 year rainfall events will increase across Vanuatu. Specifically, the intensity of these extreme rainfall events is projected to increase by approximately 8-9 mm under both very low (RCP2.6) and high (RCP8.5) emissions scenarios by 2030, while by 2090 a high emissions scenario is projected to increase the intensity of heavy daily rainfall events by 40mm. Along with flash flooding, Port Vila experiences coastal, and river flooding. While coastal and river flooding are more likely to occur during cyclone seasons or la Niña years, with the former exacerbated by sea-level rise, localised flash flooding can occur following average rains.
Cyclones. Port Vila is located within the South Pacific Convergence Zone (SPCZ) and within the Pacific cyclone belt. In 2015, Vanuatu was severely damaged by Tropical Cyclone Pam, which was recorded as the second most intense tropical storm in the Pacific Ocean in terms of sustained winds and is regarded as one of the worst natural disasters ever experienced in Vanuatu. The storm took the lives of between 11 and 16 people and displaced thousands, crippled the archipelagos infrastructure (in particular its cellular and electrical grid), and destroyed an estimated 90 percent of the country’s crops. Vanuatu is exposed to an estimated 2.4 cyclones per year with 1 per year being classified as severe.
Wave action including tsunami and storm surge. Sea-level rise compounds an already vulnerable environment that is subject to some natural subsidence as well as tectonic activity and shoreline changes with successive earthquakes and tsunamis. Vanuatu is prone to tsunamis and these have in recent years caused loss of life and property damage20. According to data from the SEAFRAME gauging station, seven tsunamis were recorded in Port Vila between 1993 and 2006
Drought. (Related to El Niño) – El Nino brings with it prolonged dry season resulting in drought. Whilst it would be difficult predicting droughts or its intensity, a predicted occurrence of El Nina is an indication that drought is eminent. Wet season rainfall provides the majority of water supplies to the smaller islands of Vanuatu. However, El Niño conditions in this part of the Pacific can shift rainfall patterns, causing significant decrease in rainfall and leading to drought conditions, causing significant declines in agricultural productivity and exports to Port Vila, which the majority of the population rely upon. More frequent El Niño events could increase the intensity and occurrence of droughts, with important implications for disaster management in Vanuatu
Sea-level rise, coastal erosion. While less susceptible to sea level rise than nearby Kiribati, sea-level rise in Vanuatu is exacerbated by the advent of climate change and hydro-meteorological hazards. Moreover, as Port Vila is located on a tectonically active area, vertical land movements cause the island of Efate to ‘sink’ at a rate of approximately 4 mm per year, thus roughly double sea-level rise impacts.
Ocean acidification. Ocean acidification and warming are immediate threats to Vanuatu’s marine ecosystems and coral reefs, which underpin Port Vila’s tourism economy, as well as being the source of a range of traditional food and material products. Damage to coral reefs and fisheries, including depletion of fish stocks. Under both high (RCP8.5) and medium (RCP 4.5) emissions scenarios, coral reef health will reach marginal conditions (as measured by aragonite saturation state dropping below 3.5) at some point between 2020 and 2030. Even under a low emissions scenario (RCP 2.6), it is possible that this threshold will be reached by 2040. In addition to the threat represented by acidification, warming of the ocean increases the risk of coral bleaching events.
Health hazards. As with other Pacific Island nations, Vanuatu’s public health sector is vulnerable to climate variability and change, particularly with regard to the increased incidences of nutritional deficiencies, and diarrheal and vector borne diseases. Outbreaks of many diseases, including conjunctivitis, are common during droughts. Limited information is available on the extent and frequency of any health issues, let alone on those with a significant link to climate variability and change. However, increased temperatures, projected flooding, and anecdotal evidence on reduced water quality point to a potentially deteriorating condition in the health sector under a changing climate.
Financial crisis: economic isolation and dependence. As discussed briefly in the Economy & Livelihood section, Port Vila, and Vanuatu more generally, maintains a large trade imbalance and lacks local economic complexity. Port Vila’s dependence on imported fuel, high-value goods, food, and tourism leaves it vulnerable to economic reverberations in the global market. Such vulnerabilities are especially acute regarding global energy costs as Vila must rely both on international shipping and diesel fuel. Therefore, a regional or global economic crisis, or energy market volatility, will cause extensive damage to the local Port Vila economy and those who depend upon it.