RAPID: Impact of ENSO Climate Shifts on Atoll Islets

沿海系统是动态和不断变化的，其行为对低洼岛国特别重要，如赤道太平洋的基里巴斯共和国，这些国家容易受到气候变化引起的海平面上升的影响。该项目的目的是检验一种假设，即厄尔尼诺/南方涛动造成的天气模式和气候变化导致基里巴斯环礁岛海岸线形态发生重大变化。这项研究将利用遥感数据比较上一个厄尔尼诺阶段结束时的海岸线特征和目前正在减弱的拉尼娜阶段。将通过实地观测对遥感数据进行检查，以确定拉尼娜基线，并据此评估未来变化的详细情况。预计结果将表明：1）稳定的海岸线与地质因素、泻湖的大小和深度直接相关; 2）在最近的拉尼娜阶段，由于来自东部的信风较强，西向海岸线较为稳定，但随着气候转向厄尔尼诺阶段，风向转向西部，它们将成为更明显的侵蚀地点; 3）通过遥感数据绘制的植被健康变化的可变性与岛屿和海岸线地形密切相关。 这项试点研究是首次尝试将遥感和详细的实地数据结合起来，系统地揭示厄尔尼诺/南方涛动对赤道小岛稳定性和动态的潜在重要作用。海平面上升是许多沿海国家关注的问题，但对于位于太平洋中部的珊瑚岛来说，这是一个巨大的问题，这些珊瑚岛仅高于海平面几米。风暴潮很容易淹没这些地区，即使相对海平面略有上升。有些地方，例如基里巴斯共和国，不必过度担心台风，但这里的天气模式与厄尔尼诺-南方涛动（ENSO）周期密切相关。可以想象，沿海过程在很大程度上取决于这一周期，而这一周期本身在未来可能在持续时间和强度上发生重大变化。因此，必须记录沿海环境如何对目前的厄尔尼诺/南方涛动水平作出反应，以便为今后的分析建立合理的模型。该项目将收集在拉尼娜现象转变为厄尔尼诺现象之前的现有阶段海岸线的即时状态数据，这可能在未来几个月内发生。

Coastal systems are dynamic and changing, and their behavior is particularly important to low-lying island nations,such as the Republic of Kiribati in the equatorial Pacific, which are vulnerable to sea-level rise from climate change. The aim of this project is to test the hypothesis that shifts in weather patterns and climate caused by El Nino/Southern Oscillation (ENSO) lead to significant changes in shoreline morphology on Kiribati atoll islets. This study will use remote-sensing data to compare shoreline characteristics at the end of the last El Nino phase with the present waning La Nina phase. The remote sensing data will be checked by field observation in order to establish a La Nina baseline against which the details of future changes can be evaluated. Results are expected to show that: 1) stable shorelines are directly linked to geologic factors, lagoon size and depth; 2) west-facing shorelines have been more stable during the recent La Nina phase because of stronger trade winds from the east, but that as climate shifts to an El Nino phase and winds shift to the west, they will become locations of more pronounced erosion; and 3) variability in changes of vegetation health as mapped through remote sensing data is intimately linked to island and shoreline topography. This pilot study represents a first attempt to integrate remote sensing and detailed field data to systematically unravel the potentially important role of ENSO on equatorial islet stability and dynamics. Sea-level rise is a concern for many coastal nations, but it is a huge problem for coral islands in the middle of the Pacific that are barely a few meters above sea level. Storm surges could easily inundate these locations with even a small rise in relative sea level. Some locations, such a the Republic of Kiribati, do not have to be overly concerned about typhoons, but here weather patterns are closely linked to the El Nino-Southern Oscillation (ENSO) cycle. It is conceivable that coastal processes are heavily dependent upon this cycle, which itself may undergo significant changes in duration and intensity in the future. Consequently, it is very important to document how the coastal environments are responding to the present levels of ENSO in order to develop rational models for future analysis. This project will gather data on the immediate state of the shoreline during the extant La Nina phase before it shifts to an El Nino pattern, which is likely in the next few months.