Tag Archives: Tuvalu

Reef islands (e.g. Tuvalu) respond naturally to sea-level changes

Megan E. Tuck, Paul S. Kench, Murray R. Ford, Gerd Masselink. Physical modelling of the response of reef islands to sea-level rise. Geology (2019), https://doi.org/10.1130/G46362.1

“Sea-level rise and increased storminess are expected to destabilize low-lying reef islands formed on coral reef platforms, and increased flooding is expected to render them uninhabitable within the coming decades. Such projections are founded on the assumption that islands are geologically static landforms that will simply drown as sea-level rises. Here, we present evidence from physical model experiments of a reef island that demonstrates islands have the capability to morphodynamically respond to rising sea level through island accretion. Challenging outputs from existing models based on the assumption that islands are geomorphologically inert, results demonstrate that islands not only move laterally on reef platforms, but overwash processes provide a mechanism to build and maintain the freeboard of islands above sea level. Implications of island building are profound, as it will offset existing scenarios of dramatic increases in island flooding. Future predictive models must include the morphodynamic behavior of islands to better resolve flood impacts and future island vulnerability.” click here

For more discussion click here.

Tuvalu and most Pacific islands have grown in size. They are not sinking into the sea.

“TIME titled it’s Thursday cover story, “Our Sinking Planet.” There’s just one problem: Scientific studies show Tavalu’s islands, indeed most Pacific islands, have actually grown in the face of sea level rise.” click here

Tuvalu is growing, not sinking

“The Pacific nation of Tuvalu—long seen as a prime candidate to disappear as climate change forces up sea levels—is actually growing in size, new research shows.” click here

South Pacific island shorelines expand

“the dramatic impacts of climate change felt on coastlines and people across the Pacific are still anecdotal” see discussion here

Michino Hisabayashi, John Rogan & Arthur Elmes. Quantifying shoreline change in Funafuti Atoll, Tuvalu using a time series of Quickbird, Worldview and Landsat data Journal GIScience & Remote Sensing Volume 55, 2018 Issue 3

Funafuti Atoll, Tuvalu is located in the southwestern Pacific Ocean, which has experienced some of the highest rates of global sea-level rise over the past 60 years. Atoll islands are low-lying accumulations of reef-derived sediment that provide the only habitable land in Tuvalu, and are considered vulnerable to the myriad possible impacts of climate change, especially sea-level rise. This study examines the shoreline change of twenty-eight islands in Funafuti Atoll between 2005 and 2015 using 0.65 m QuickBird, 0.46 m WorldView-2, and 0.31 m WorldView-3 imagery using an image segmentation and decision tree classification. Shoreline change estimates are compared to previous study that used a visual interpretation approach. The feasibility of estimating island area with Landsat-8 Operational Land Imager (OLI) data is explored using CLASlite software. Results indicate a 0.13% (0.35 ha) decrease in net island area over the study time period, with 13 islands decreasing in area and 15 islands increasing in area. Substantial decreases in island area occurred on the islands of Fuagea, Tefala and Vasafua, which coincides with the timing of Cyclone Pam in March, 2015. Comparison between the WorldView-2 shoreline maps and those created from Landstat-8 indicate that the estimates tend to be in higher agreement for islands that have an area > 0.5 ha, a compact shape, and no built structures. Ten islands had > 90% agreement, with percent disagreements ranging from 2.78 to 100%. The methods and results of this study speak to the potential of automated EoV shoreline monitoring through segmentation and classification tree approach, which would reduce down data processing and analysis time. With the growing constellation of high and medium spatial resolution satellite-based sensors and the development of semi or fully automated image processing technology, it is now possible to remotely assess the short and medium-term shoreline dynamics on dynamic atolls. Landsat estimates were reasonably matched to those derived from fine resolution imagery, with some caveats about island size and shape.

Pacific Islands growing, not sinking; populations unsustainable?

Tuvalu should be much more concerned about a tsunami or storm surge. In any case, this population is not sustaining itself and will not be around long enough to see a 3 foot rise in sea level whatever the cause. (click here)

“Tuvalu, a scattering of nine coral atolls that is home to about 11,000 people, is one of several Pacific nations threatened by rising seas blamed on global warming.”

“Many are barely one meter (three feet) above sea level and scientists warn that nations such as Tuvalu, Kiribati and Tokelau could disappear beneath the waves if climate change continues unabated.”

“Sounds dire. But a pesky thing called observable science keeps getting in the way of the the island nations actually sinking.” click here