Modeling the future of sand beaches

Sand beaches are associated with sea level stillstands and may occur when waves have cut sufficiently wide shore platforms for them to repose upon. During the present near-stillstand lasting over the past 5000 years, waves have cut wide platforms, and wherever sufficient sand is available, beaches have formed along the world's coastlines. Global warming causes sea level to rise and there is good evidence that the present near-stillstand is being terminated and replaced by much higher rates of sea level rise. Models show that during rapid sea level rise the future of sand beaches largely depends upon the rate of development of new wave-cut platforms, a process that proceeds at much faster rates on gently sloping coasts than on steep coasts backed by sea cliffs. Sand beaches on gently sloping coasts such as the U.S. east coast will survive by washover and inland migration. Along steep coasts backed by sea cliffs, such as the U.S. west coast, sea level rise will more likely result in drowned platforms with cliffs plunging to the sea and a loss of sand beaches.