The daily rise and fall of the tides are intimately familiar to those
living on the coast. However, due to sea-level rise, what communities in
the United States now experience as the highest, lowest, and average
water levels on a typical day no longer corresponds to the official
definitions of high tide, low tide, and mean sea level, respectively.
Water levels now regularly exceed official high tide along parts of the
Chesapeake Bay, Gulf Coast, and Puerto Rico. In other words, yesterday's
high tide is becoming today's new normal. This demonstrates how
sea-level rise is radically redefining the American shore.