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.
