In the next 30 years, sea level in the U.S. will rise as much as it did in the last 100 years, increasing the frequency of high-tide flooding, pushing storm surge to extremes, and inundating vulnerable coastal infrastructure with saltwater.
Scientists are increasingly certain that the U.S. coasts will witness another 10 to 12 inches of sea level rise by 2050, according to an interagency report led by the National Oceanic and Atmospheric Administration.
"This report is a wake-up call for the US, but it's a wake-up call with a silver lining," NOAA chief Rick Spinrad said at a news conference on Tuesday. "It provides us with information needed to act now to best position ourselves for the future."
The ramifications of that prediction are enormous. According to scientists, the projected sea level rise will result in a significant increase in the frequency of coastal flooding, even on sunny days. High-tide flood events in coastal cities such as New York, Washington, and Miami have already doubled in annual frequency since 2000, researchers say, transforming what was once a "rare event" into a "disruptive problem."
Every inch of sea level rise increases hurricane storm surge, coastal erosion, and wetland loss - effects that U.S. coasts are already well acquainted with.
The amount of sea level rise experienced by the U.S. after 2050 is highly dependent on how much the world reduces fossil fuel emissions and limits global temperature rise.
For example, NOAA believes that sea level rise in the U.S. might be limited to 2 feet by the end of the century if global warming is kept to roughly 2 degrees over pre-industrial levels. If temperatures continue to rise, the projection will rise to 7 feet.
The uncertainty about future changes in the world's greatest ice sheets and how they will adapt to rapid temperature rise is part of the reason for the wide range. By the end of the century, faster melting of the Greenland or West Antarctic ice sheets could result in catastrophic sea level rise in the U.S.
Ben Hamlington, the lead of NASA's Jet Propulsion Laboratory's sea level change team and a co-author on the report, highlighted the potential collapse of Antarctica's Thwaites glacier, also known as the "Doomsday glacier," which scientists have said would cause irreversible changes around the world.
Tens of millions of people already live in flood-prone coastal areas in the U.S., and with more people migrating to the coasts each year, partly due to ongoing land development, researchers predict a dramatic increase in human exposure as well as the country's critical infrastructure.
However, researchers believe that by reducing fossil fuel emissions, we can limit the worst long-term outcomes. High-end projections for 2100 can be avoided if fossil-fuel emissions are reduced.
"It's collectively in our hands to determine what our future scenario will actually be," researchers concluded.
