Heat waves, flooding, ice storms and drought are some of the many currently foreseeable scenarios that many countries will face in coming decades and many experts are attributing this to climate change.
Many reports have repeatedly highlighted the risks and its potential impact to the lifestyles of those who are living along the coastal areas. Aside from the usual narrative that focuses just on the rise in seawater level, many experts are also trying to understand how the rise in seawater will impact livelihoods and how tolerable communities will get before they start to exhibit migration behaviours.
Property values in most coastal real estate markets do not reflect this risk at all. For better appreciation of the challenge, I highlight a study that was performed on the USA market and it showed that more than 300,000 of today’s coastal homes, with a collective market value of about USD$117.5 billion today, are at risk of chronic flood in 2045—a timeframe that falls within the lifespan of a 30-year mortgage issued today (Dahl, Cleetus, Spanger-Siegfried, Udvardy, Caldas, 2018).
The last thing that most planners might want is mass panic that is caused by frequent media reporting on high sea water level rise scenarios. This narrative only creates anxiety and confuses homeowners and migration patterns.
Forecasts serve as guiding beacons, and are built with predictive analytic techniques that depend heavily on historical records and other highly-correlated factors. It cannot be ignored but we must also understand that the predictions can change when the current condition changes.
We could stay passive throughout the entire 20 years period and wait for the potential future to arrive. Or we can refer to these forecasts for science-based policy making, create tools to better understand our environment and also contribute what we can to help the environment on other fronts.
Understanding how tolerable communities are to changing climate is a tiny shift in research perspective but if it is taken up by the reporting platforms, it could serve as a balancing voice by enabling a slightly more in-depth understanding of how flooding interacts with natural terrains and built environment elements and even perhaps spark more research on how one could live with water.
Because of my background in sustainable urban development, I’ve always been quite interested in understanding how climate change will affect coastal communities and low-lying islands. One of my research interests is Guam island which is about 540 km2 and its highest point to mean sea level is about 407 m. I like the island’s profile because it is quite similar to about 40% of the island countries that are existing currently.
This was a modelling that I recently performed on Guam island and when based on extreme scenarios, we can see that the flooding could become really bad:
Year 2040: 1.8 ft = 0.54864 metres
Year 2060: 3.9 ft = 1.18872 metres
Year 2080: 6.69 ft = 2.039112 metres
Year 2100: 10.47 ft = 3.191256 metres
Based on the visualisation presented by the modelling, it is clear that the communities that are living in the perimeters will be most affected. The entire area that I’ve highlighted in blue represents the potential land loss if the seawater level rose to around 0.55 metres. The modelling showed that this could be possible by 2040.
In another scenario, we can see that the situation becomes even worse when the seawater rises to about 3.2 metres. Most of the outlying land area get consumed and it is assumed that this would take place by 2100.
This gives me a better understanding of how the seawater will interact with the outermost perimeter of Guam island and certainly sets me rethinking about the much coveted coastal living.
So far, I’ve not seen much research on how the rise in seawater level will affect the geotechnical profile of the subsoil strata inland. If it does weaken the inland clayey strata, high-rise buildings that are built on soft ground might be at risk. Planners might have to delve into the intricacies of subsoil conditions to augment current urban planning methods – arranging for higher rise buildings to be built on stronger foundations that comprise mainly of rocks and granite.
I’d be very interested to learn more about this area.
References
Dahl, K., Cleetus, R., Spanger-Siegfried, E., Udvardy, S., & Caldas, A. (2018, December). Using the Quantified Risk of Sea Level Rise and Tidal Flooding to Coastal Real Estate Markets as a Tool for Engaging Communities and Financial Actors. In AGU Fall Meeting Abstracts (Vol. 2018, pp. PA41D-1359).
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