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The Unlikelihood of Climate Refugees Driven By Future Sea Level Rise

Paper Reviewed
Esteban, M., Jamero, M.L., Nurse, L., Yamamoto, L., Takagi, H., Thao, N.D., Mikami, T., Kench, P., Onuki, M., Nellas, A., Crichton, R., Valenzuela, V.P., Chadwick, C., Avelino, J.E., Tan, N. and Shibayama, T. 2019. Adaptation to sea level rise on low coral islands: Lessons from recent events. Ocean and Coastal Management 168: 35-40.

One of the great concerns associated with model-based predictions of future climate change is the possibility that warming temperatures will melt large portions of polar ice sheets, thereby raising sea levels by up to a meter or more by 2100. Such a rise is postulated by climate alarmists to cause widespread flooding of coastal regions all around the world, wreaking havoc among millions of inhabitants in such low-lying areas, and effectively turning their citizens into climate refugees.

Fortunately, the likelihood of this scenario ever occurring is quite low. As we have shown in a previous review (see Watson (2018)) observational trends of sea level rise over the past decade remain far below those predicted by models. What is more, the review paper by Duvat (2019) reveals that the vast majority of small islands surveyed to date are stable or gaining in area in response to the sea level rise that has occurred over the past few decades.

Now, there is a third reason to doubt the model-based projections of sea-level rise refugees; and that reason is elucidated in a new paper by Esteban et al. (2019).

Writing as background for their work, the sixteen researchers that authored this new study say "there have been fears that many low-lying atoll islands around the world could disappear as a consequence of climate change and sea level rise, leading to mass migration and threatening the existence of several island nations." However, they note that such fears ignore the power of human adaptation, writing that "humans have an innate and often underestimated capacity to adapt to changes in their environment." And thus it was their hypothesis that humanity would be able to "adapt and arrive at solutions even when confronted with cases of rapid rises in water levels" so as to avoid becoming climate refugees from future sea level rise.

In support of their thesis, Esteban et al. presented three case studies where geologic (tectonic/earthquake) or anthropogenic (groundwater extraction) events have caused rapid coastal subsidence in populated areas, utilizing them as proxies in understanding the human response to challenges caused by future sea level rise. The first location was the Tohoku coastline of Japan, which experienced an earthquake in 2011 that caused a 78-120 cm regional lowering of the land. As a result, much of the coastline is said by them to be "barely above mean sea level, with large portions of it being flooded at high tide." But, rather than abandon these homes and the surrounding infrastructure, the Japanese government initiated a large public works program to build up and "return the coastal areas to their original levels or even increase them, and ensuring that no ground was lost to the sea." In the end, therefore, over 200 km of coastline was reclaimed in a handful of years, demonstrating to the authors that "adapting to the much slower sea level rise that is projected to take place in the course of the 21st century is technically feasible and possible."

The second case study examined by Esteban et al. was located on the Tubingon Islands, Philippines. Again, a large-magnitude earthquake caused rapid and extreme subsidence (in excess of 1 m), resulting in inland tidal flooding during normal high tides. Measurements in 2016 revealed that the islands "became completely inundated during the highest tides of the year, with median flood levels reaching up to 20.5-43 cm, and partial flooding taking place between 44 and 135 days per year." Attempts were made by municipal authorities to relocate the island citizens to the mainland, yet most all of them chose to stay despite the flooding. These residents have rebuilt their homes by elevating them on coral rocks or stilts. What is more, they have adapted by constructing small elevated pathways across the islands to maintain mobility during high tides.

The final case study was from Jakarta, Indonesia. Due to high ground water extraction the land there has been subsiding at a rate of 9.5 to 21.5 cm per year, which has caused a large extent of the coastal area to be situated below sea level and which suffered extensive flooding in 2007 due to high tides. In response, however, the community built large dykes to hold back seawater and has elevated some port wharfs and other buildings.

In summing up the findings from these three case studies, Esteban et al. write that they "found no evidence that these areas will be abandoned, and it seems that many adaptation methods are possible through modern engineering methods or human ingenuity." Therefore, they conclude that "it is possible for coastal and island populations to adapt to rising sea levels, given that even the highest sea-level rise scenarios are projected to happen at much slower rates than the case studies outlined." And because those projected sea level rise scenarios are far and above that which is occurring in the observational record, it gives us all the more confidence that there will never be any true cases of climate refugees from future sea level rise.

References
Duvat, V.K.E. 2019. A global assessment of atoll island platform changes over the past decades. WIREs Climate Change 10: e557.

Watson, P.J. 2018. How well do AR5 sea surface-height model projections match observational rates of sea-level rise at the regional scale? Journal of Marine Science and Engineering 6: 11, doi:10.3390/jmse6010011.

Posted 8 April 2019