French Poynesia - Climate
French Polynesia enjoys a tropical climate characterized by two seasons: a wet season from November to April and a dry season from May to October. The climate of French Polynesia is tropical, oceanic, hot and humid. Tempered by the trade winds, the climate is pleasant throughout the year. The water temperature of the lagoons oscillates between 23° and 26°. The warm season lasts from December to February with temperatures of 27 to 35° C. From March to November, the temperature oscillates between 21° and 27°. The rainy season is usually during the warm season.
Rainfall amounts over the period 1961-2011 shows no significant trend related to climate change, but highlight the interactions between ENSO, the South Pacific Convergence Zone (SPCZ) and rainfall during the latest positive phase of the Inter-decadal Pacific Oscillation (IPO) (1977-1999). During this particular phase, the SPCZ is closer to Tahiti and induces positive large-scale precipitation. On interannual time scales, more frequent and strong El Nino events favour a northward SPCZ migration. This northern position causes a surface flux over Tahiti Island, which forces orographic precipitation on the windward side.
Climate change is a major global problem. Over the coming decades, the international scientific community predicts increasing average annual temperatures, changing rainfall patterns, rising sea levels, ocean acidification, and intensification of tropical cyclones. Due to its geographical characteristics and main economic activities, French Polynesia is particularly vulnerable to all of these likely impacts.
With its South Pacific neighbors (mostly small island developing states), French Polynesia is one of the most sensitive countries in the world to the increasing concentration of greenhouse gases. In spite of French Polynesia's high vulnerability, there is limited data on the local impacts of climate change, and what knowledge exists is very fragmented.
Rising sea levels are an imminent threat to island nations around the globe, especially small islands in the Pacific. Even the largest of the French Polynesian islands, Tahiti, is under threat of losing coastline. The Intergovernmental Panel on Climate Change’s 5th Assessment Report published in 2013 describes the primary contributors to sea-level change as (1) the expansion of the ocean as it warms due to increased atmospheric temperatures, and (2) the transfer of water currently stored on land as ice, to the ocean.
A December 2011 conference in Tahiti said some of French Polynesia's islands will be wiped off the map due to global warming. The effects of rising tides in the region were part of discussions involving politicians and scientists from France, the European Union and the Pacific Island region in Papeete. Delegates heard that French Polynesia's 270 thousand inhabitants spread over an area the size of Europe will be affected before the end of the century by higher sea levels. It was estimated the level will rise by about 50 centimetres if global warning doesn't speed up. Scientists said the Tuamotu archipelago which rises one to two metres above sea level could disappear.
With the coastal areas of the island drawing tourists with visions of a tropical paradise combined with the difficulty of building further inland, the large number of hotels and resorts along the coast will be the front line for future erosion and loss of shoreline to sea-level rise. The response of the tourism industry to these environmental challenges will be critical to the future economic stability of French Polynesia.
Strong tropical lows and cyclones are rare in French Polynesia since the waters in this area of the Pacific are relatively cold. Tahiti is currently most prone to experience cyclones from November to March, but the storm systems that form in the region usually pass south of the island. There is an expected poleward expansion of the reach of storm tracks, however, which would likely contribute to a dampening of sea level rise in the mid to low latitudes. Considering this shift in weather patterns accompanying climate change, Tahiti is expected to experience fewer storms and perhaps decreasing effects of sea-level rise over time, though there is still a great deal of uncertainty in terms of future impacts.
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