Sea level rise and the dangers of living in coastal cities

The new Intergovernmental Panel on Climate Change’s (IPCC) 5th assessment report has upgraded their predictive models to increase the reliability and confidence of future climate change scenarios. As a temporary resident of Miami, which is largely at or just above sea level, I was particularly interested in the new sea level rise projections. The IPCC is now 95% confident that sea levels will rise somewhere between 0.25 to 1 meter (~1 to 3 feet) by the year 2100. This may not sound like a lot but if we consider that many of the world’s largest cities are located at or below sea level then the repercussions of even a 1 ft increase in sea level rise can be devastating.

Projections of global mean sea level rise over the 21st century relative to 1986–2005 from the combination of the CMIP5 ensemble with process-based models, for RCP2.6 and RCP8.5. The assessed likely range is shown as a shaded band. The assessed likely ranges for the mean over the period 2081–2100 for all RCP scenarios are given as coloured vertical bars, with the corresponding median value given as a horizontal line. For further technical details see the Technical Summary Supplementary Material

Projections of global mean sea level rise over the 21st century relative to 1986–2005 from
the combination of the CMIP5 ensemble with process-based models, for RCP2.6 and RCP8.5. The assessed likely range is shown as a shaded band. The assessed likely ranges for the mean over the period 2081–2100 for all RCP scenarios are given as coloured vertical bars, with the corresponding median value given as a horizontal line. For further technical details see the Technical Summary Supplementary Material

According to the Organization for Economic Co-operation and Development’s 2007 report on coastal flooding, Miami ranks as the number 9 city worldwide in terms of population exposed to coastal flooding, but Miami is the number one ranked city in the US, followed by New York. For Miami alone it is expected that almost 4.8 million people will be affected by coastal flooding by 2070, but this number is a drop in the bucket when we consider that the top 8 cities on this list, all outside of the US, project having a combined population of 71+ million people affected by coastal flooding related to sea level rise.

What happens when 71 million or even 4 million people are displaced by sea level rise? Rolling Stone provides one possible scenario in this recently published article that simulates what might happen in Miami. The article paints a grim picture for South Florida but I imagine situations will be much worse in less economically developed countries such as India, Bangladesh, and Thailand. The social unrest and economic losses due to even modest increases in sea level are staggering. If we consider only the top 20 cities worldwide (Miami is #1) in terms of assets exposed to coastal flooding, we are looking at a $3 trillion global loss by 2070. This was about 5% of global GDP in 2005.

Millions of displaced Bangkok residents went without food or clean water for weeks after devastating floods swept through the city in 2011. Photo courtesy of washingtonpost.com

Millions of displaced Bangkok residents went without food or clean water for weeks after devastating floods swept through the city in 2011. Photo courtesy of washingtonpost.com

These projections do not even begin to tell the story of how our ecosystems and the services those systems provide to humans will be changed. Coastal wetlands, which protect us from large storm surges will be submerged and likely lost because they cannot migrate inshore due to human development. Coral reefs, which depend on light for growth and serve as nurseries for several economically important fish species, will be further submerged, receiving less light and degrading over time. At coastal cities, salt water is already intruding into freshwater aquifers, contaminating our drinking water and this trend will only get worse with further rises in sea level.

No matter how you put it sea level is rising and the negative aspects of sea level rise are downright frightening. My advise, buy property in Colorado.

A cool but scary webpage let’s you play around with different sea level scenarios for cities in the US. I encourage you to go to this webpage and see how your city or favorite beach vacation spot fares against rising sea levels. However, results should be interpreted with caution as population estimates are based only on the city population itself and ignores the greater metropolitan area, which means actual number of people impacted by sea level are much greater than displayed on the webpage.

 

 

 

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