High Tide Rising: Our Vanishing Shores

By Kate Sheppard

(This post originally appeared on Mother Jones .)

Climate Central has released a new in-depth report on the combined impacts of rising seas and storm surges. With rising water levels, more people and property are at risk—especially during storms, which force water farther inland. Here’s an excerpt from the executive summary:

Global warming has raised sea level about eight inches since 1880, and the rate of rise is accelerating. Scientists expect 20 to 80 more inches this century, a lot depending upon how much more heat-trapping pollution humanity puts into the sky. This study makes mid-range projections of 1 to 8 inches by 2030, and 4 to 19 inches by 2050, depending upon location across the contiguous 48 states.

Rising seas dramatically increase the odds of damaging floods from storm surges. For more than two-thirds of the locations analyzed (and for 85% of sites outside the Gulf of Mexico), past and future global warming more than doubles the estimated odds of “century” or worse floods occurring within the next 18 years — meaning floods so high they would historically be expected just once per century. For more than half the locations analyzed, warming at least triples the odds of century-plus floods over the same period. And for two-thirds of the locations, sea level rise from warming has already more than doubled the odds of such a flood even this year.

As the report notes, five million people live less than four feet above current high tide levels. Climate Central found that three million acres of key infrastructure like roads, bridges, schools, farms, and hospitals are also at risk from flooding as sea levels rise.

The report also includes a closer look at heavily impacted states such as Florida, which is home to 8 of the 10 most-impacted cities. Some of the stats on how fast it’s happening are pretty shocking:

1. Odds of a 100-year flood or worse by 2030, with sea level rise from global warming: 25%
2. Odds without global warming: 10%
3. Bottom line: global warming multiplies the odds by 2.6x
4. Historic local sea level rise rate: 1.1 inches/decade
5. Projected new sea level rise by 2050: 13 inches

As are the figures on how much is at risk:

1. Population at risk: 2.4 million
2. Homes at risk: 1.3 million
3. Land area at risk: 1.8 million acres
4. Towns and cities where at least half the population is at risk: 107
5. Counties where at least 10% of the population is at risk: 8
6. Cities with the largest total exposed populations, ranked most to least: Hialeah, Pembroke Pines, Cape Coral, Miami Beach, Plantation, Miramar, Fort Lauderdale, Davie, St. Petersburg, Miami
7. Counties with the largest total exposed populations, ranked most to least: Miami-Dade, Broward, Lee, Pinellas, Collier, Hillsborough, Monroe, Charlotte, St. Johns, Brevard
8. Miami-Dade and Broward Counties each have more people living on land below 4 feet than any US state except Florida itself and Louisiana.