By Alex Laplaza
The Northeast Atlantic coast of the U.S., stretching from Virginia to Maine, is more likely to adapt than succumb to rising sea levels over the next century, according to a study led by the U.S. Geological Survey (USGS). The study, published in Nature Climate Change, posits, “Nearly 70 percent of this coastal landscape has some capacity to respond dynamically.” In other words, 70 percent of the ecosystems that make up the Northeast Atlantic coast of the U.S. have some capacity to change and adapt to rising sea levels over the next several decades.
The challenge of coastal adaptation to sea level rise (SLR) has significant implications for U.S. economy and population. According to the National Ocean Economics Program (NOEP), in 2014, northeastern shoreline adjacent counties comprised over 10 percent of the total U.S. population, over 10 percent of total U.S. employment, and nearly 15 percent of U.S. GDP.
The USGS study is based off a probabilistic model that evaluates the likelihood that an area will flood or adapt to sea level rise. Previous models calculated uniform responses to SLR across the Northeast’s varied landscapes. In academic circles, this is typically called “the bath-tub model” – a model that merely inputs rising sea levels across topographies. As a result, previous models tend to over-predict flooding of low-lying areas as sea levels progressively rise.
Developed in collaboration with Columbia University’s Earth Institute, the USGS model is much more innovative and nuanced than its predecessors. It’s the first of its kind to factor geological and biological forces that reshape coastal landscapes. The model includes the potential for dynamic coastal change across geographies of dry land, wetlands, and open water. Additionally, the USGS model is more expansive and long-term, calculating detailed projections of more than 9.4 million acres through the 2080s. The study argues, “This approach is well suited to guiding coastal resource management decisions that weigh future SLR impacts and uncertainty against ecological targets and economic constraints.”
The result is a much more dynamic Northeast U.S. coastline. For example, many barrier islands in this model may migrate inland, build dunes, change shape, or be split by new inlets as tides, winds, waves and currents sculpt sands. However, as author Erika Lentz, a geologist at the USGS, points out, “Our model suggests that even natural changes may pose problems. For example, the likelihood that barrier islands will change could impact the infrastructure and economies of coastal communities.
Ultimately, the new model provides a much more accurate and detailed picture of the Northeast coastline’s dynamism. Adaptation is complex, bringing with it an improved resilience and additional adaptation challenges.