DOES ACCELERATION MATTER?

While there is no significant debate within the scientific community regarding the likelihood of an acceleration in the rate of sea level rise during this century, there has been a rising degree of political consternation regarding both this prediction and its potential economic impacts. One result of this political wrangling in North Carolina is a recent bill passed by the state legislature requiring state agencies to ignore rising sea level for a number of years, and for the state’s Science Panel (advising the Coastal Resources Commission) to write another report in a few years. Those advocating for this bill seemed to suggest (or even believe) that if sea level does not rise at an accelerating rate, as predicted, there is no need to change current coastal management practice nor will there be a need to consider increasing vulnerability to infrastructure as a result of sea level rise. We are always amazed at the strength of the desire amongst some segments of the coastal community to pretend that change is not occurring. The current rate of global, eustatic sea level rise as measured from satellite altimetry is approximately 3.1 mm/yr. Even without an acceleration in the rate of rise, we will be guaranteed 31 cm over the next 100 years. For many coastal areas in the USA and around the world, this will be enough. None of our coastal erosion problems are going to get better, only worse. Land loss in coastal Louisiana is only going to become harder to address. 31 cm of sea level rise will cause major problems for south Florida, Tidewater Virginia, and the North Carolina Outer Banks. This amount of sea level rise will change the nature of agriculture in many low-lying areas. This is with no acceleration. For many coastal communities and the coastal engineering firms that serve them, this means increasingly costly beach nourishment projects with shortened project durability. What we all must come to grips with is this: whether sea level rises 31 cm or 1 m over the next 100 years, the coast will look differently at the end of the century than it does now. Anyone seriously interested in the long-term preservation of a viable coastal economy and a viable coastal environment needs to be willing to acknowledge this fact, and begin to plan wisely for this transition.