Data from the tide gauge in Charleston harbor since 1900 shows the sea level is trending upward at a rate of 12.4 inches per century . However , as global warming increases with the attendant warming of sea water , the rate of increase is expected to accelerate . The most conservative estimates of the increase lead to the green curve in the chart , and the least conservative to the red trend line . Much of the sea level increase thus far is from ocean water expansion from warming , but going forward ice melt from Greenland , glaciers around the world , and from Antarctica will play an increasingly significant role .
To design a response to sea level rise and its effects , the City of Charleston has decided to look out about 50 years . The city assumes a sea level increase of about 1.5 feet when thinking about short-term investments such as the cost of a parking lot . On the other hand , a 2.5-foot rise will be assumed when thinking about longer-term investments such as public buildings and emergency routes .
One thing clear from all of the scientific information available is that the sea level is rising inexorably in the short term and communities must plan for it . Any global changes to ameliorate the effect will not change the upward trend in the short term , only in the longer term . After about 50 years the rising sea level scenarios increasingly diverge , and amelioration will be more difficult .
The most important action to take now is to think about adaptation , strategic planning , and resiliency . The NOAA Office of Coastal Management has a U . S . Climate Resilience Toolkit in which they suggest areas focus on climate “ stressors ” that most threaten people , buildings , and the economy . Next , communities should determine what would be most affected by climate change and sea level rise , and begin to draw up a list of potential solutions . The fourth step is to analyze the costs and benefits of the various steps , and finally to implement the plan .
The City of Charleston is well along in their planning , and Folly Beach and Beaufort have begun planning . The City of Charleston recently appointed Mark Wilbert as Director of Emergency Management and Resilience . Wilbert said , “[ T } idal flooding is one of the top challenges facing the city now .” Projects already underway include multimillion-dollar drainage projects along Market Street and the Crosstown . This work involves digging deep tunnels and installing pump systems that siphon water from the tunnels back into the harbor , and a rebuilt wall along the Battery is being planned .
Finally , the city is undertaking a number of other initiatives such as clearing storm drains and encouraging different landscaping plans .
A committee of the Town of Kiawah Island has been meeting for the past year with a number of scientists and local engineers and architects . The committee spent considerable time learning about Kiawah ’ s infrastructure : the stormwater pond system , the roads , and the water and sewage disposal systems . A report from the committee is expected in fall 2018 .
One particularly interesting report was issued by the Union of Concerned Scientists ( UCS ) in the summer of 2017 ( When Rising Seas Hit Home ). This was followed by an article in the Post & Courier by Tony Bartleme ( July 2017 ) in which he said “ By 2060 , under moderate sea-rise scenarios , [ UCS ] predicts 16 percent of peninsular Charleston will see debilitating floods at an average rate of every other week . By then , chronic floods also will affect roughly 17 percent of James Island and 41 percent of Kiawah Island .” This is of obvious concern to Kiawah Island , and the committee is looking carefully at the data that underlies this scenario .
Global warming and the attendant sea level rise , with all of its consequences , is “ baked into ” our near future . It is incumbent on us to prepare for this future in responsible and meaningful ways . NK
Useful Sources of Information
1 . www . charlestonresilience . net . In that website , see “ Primer on Sea Level Rise and Future Flooding ,” D . Marcy and R . Jackson . ( www . charlestonresilience . net / wp-content / uploads / 2017 / 03 / flooding _ primer _ marcy . pdf )
2 . City of Charleston , flood maps and sea level rise maps : gis . charleston-sc . gov
3 . coast . noaa . gov 4 . toolkit . climate . gov
5 . Union of Concerned Scientists , When Rising Seas Hit Home : www . ucsusa . org / global-warming / global-warming-impacts / when-rising-seas-hithome-chronic-inundation-from-sea-level-rise #. WnnAUGaZPOQ
6 . Global Sea Level Rise Scenarios for the U . S . National Climate Assessment : scenarios . globalchange . gov / sites / default / files / NOAA _ SLR _ r3 _ 0 . pdf
7 . scenarios . globalchange . gov / sites / default / files / NOAA _ SLR _ r3 _ 0 . pdf
8 . Tony Bartelme , Post & Courier , “ Slowly but surely , South Carolina ’ s incredibly complex shoreline is losing ground ,” February 12 , 2018 .
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