Global sea-rise: An early warning

Abstract

One of the most important problems facing coastal communities today is the effects of a global sea-rise on coastline habitat and infrastructure. Such a rise could inundate lowlands and wetlands, erode beaches, and exacerbate coastal flooding. Furthermore, rising sea level can influence the rate of salt-water intrusion into coastal aquifers, cause expansion of the salt-water wedge in estuaries, and increase the probability of damage from storm surges along coastlines. Predicting shoreline retreat and land loss rates is critical to planning future coastal zone management strategies and assessing biological impacts due to changes in or destruction of habitat. To date, long-term coastal planning has been done piecemeal, if at all (NRC, 1995). Consequently, facilities are being located and entire communities are being developed without consideration to the potential costs to relocate and/or protect them from the effects of sea-level rise, flooding, and/or loss of natural resources. An average rise in global ocean levels of just a few inches could have devastating effects on coastal towns, cities, and ecosystems worldwide. More than 100 million people live within 1 meter (3.28 feet) of the mean sea level (Douglas & Kearney, 2001). The problem is exceptionally urgent and serious for the low-lying small island nations of the world. The Intergovernmental Panel on Climate Change concluded in 2006 that by 2100 the sea-level could rise as much as 0.58 meters (23 inches) (Solomon et al., 2007). Current estimates of sea-level rise by 2100 range between 0.30-0.91 meters (1-3 feet). The range reflects uncertainty about global temperature projections and how rapidly ice sheets will melt or slide into the ocean in response to the warmer temperatures. Regardless of the future uncertainty, the current rate of sea-level rise is more than double the average sea-level rise seen over the past few centuries. Equally alarming is the fact that the rate of sea-level rise appears to have increased exponentially over the past few decades.