Sea level rise is a definite concern; but what is more worrisome sooner is that the land is sinking. Coastal cities are inducing several changes that are sinking the land faster than the water is rising, increasing the threat and damage to coastal infrastructure. Pumping water out of aquifers, which then shrink; diverting flood waters, which reduce the natural delta and land replenishment; maybe even the weight of all those buildings add up to many cities sinking by inches every year;
“The fastest subsidence rate, 250 millimeters or nearly 10 inches per year, was seen in China’s Huanghe Delta. Southeast Asia saw 30 to 60 millimeters (1.2 to 2.4 inches) per year, while Katrina-ravaged portions of New Orleans saw rates as high as 35 millimeters (1.4 inches) per year.” – NASA
To people living along coasts, the cause isn’t as important as the effect. Sea level rise + coastal land sinking = an immediate need to protect, adjust, or possibly move. River deltas alone account for 500 million people. The cost will be significant.
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