Developing a Coastal Risk Indicator for Sea Level Rise

Coastal sea level rise is one the most important potential environmental risks. Multiple satellite altimeters flying on the same repeat orbit track have allowed estimation of global mean sea level for the past 20 years, and the time series has yielded information about the average rate of sea level increase over that time. Due to the duration, consistency, and inter-calibration of the altimeter measurements, the time series is now considered a climate record. The time series has also shown the strong dependence of sea level on interannual signals such as the ENSO and the NAO. But the most important sea level effects of climate change will be felt on the regional and local scales. At these smaller scales, local effects due to topography, tides, earth deformation (glacial isostatic adjustment (GIA), subsidence, etc.), and storm surges must also be considered when estimating the risks of sea level change to coastal communities. Recently, work has begun to understand the methods applicable to estimating the risks of expected sea level change to coastal communities (Strauss et al., 2012; Tebaldi et al., 2012). Tebaldi et al (2012) merged the expected global mean sea level increase from the semi-empirical model of Vermeer and Rahmstorf (2009) with historical local tide gauges to predict increases in storm surge risk posed by increasing sea level. In this work, we will further explore the currently available data and tools that can potentially be used to provide a sea level climate change indicator and local risk assessment along US coasts. These include global and regional sea level trends from the satellite altimetry climate record, in situ tide gauge measurements and the historical extremes at each location, local tide and storm surge models, topographic surveys of vulnerable coastlines, GIA models, and measurements of local subsidence and crustal deformation rates. We will also evaluate methods to estimate the increased risk to communities from sea level change coupled with storm surges and tides. Since large-scale ocean modes such the ENSO and NAO can have large temporary effects on local sea levels, we will also investigate whether the timing of these modes can be used in this risk assessment. The goal is to produce a climate indicator for use by planners, policy makers, and the general public, such as the National Climate Assessment, and as an ongoing effort to assess changing risks from expected sea level rise. References Strauss, B., R. Ziemlinski, J. Weiss, and J. Overpeck. "Tidally adjusted estimates of topographic vulnerability to sea level rise and flooding for the contiguous United States." Environmental Research Letters 7, no. 1 (2012). Tebaldi, C., B. Strauss, and C. Zervas. "Modelling sea level rise impacts on storm surges along US coasts." Environmental Research Letters 7, no. 1 (2012). Vermeer, M., and S. Rahmstorf. "Global sea level linked to global temperature." Proceedings of the National Academy of Sciences 106, no. 51 (2009): 21527-21532.