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.
38 Naturally Kiawah