Since 1880, climate change and global warming have caused sea levels to rise about eight inches. Evidence points to that rate of rise accelerating, and higher sea levels mean a greater risk of destructive floods from storm surges. Some models show the likelihood of these devastating 100-year floods doubling by the year 2030, which could put a huge number of people at risk. Nearly five million people are living in homes that are less than four feet above high tide, which is lower than the 100-year flood line for most locations. In addition, scientists are predicting a sea level rise of two to seven more feet in this century, depending on how much more greenhouse gases are added to the atmosphere.

But, how does this play out for people living near the coasts? And what will pictures of sea level rise actually look like?

Global Sea Level Rise Maps 

We’ve already seen unusually strong hurricanes and storm surge flooding along the Texas coast, Louisiana, Florida, the eastern seaboard and even New York and Long Island. A study from the Union of Concerned Scientists shows that continued sea level rise could bring catastrophic flooding to nearly 670 coastal communities, with 26 floods per year or more.

This would mean chronic flooding from Maine all the way around to Texas, as well as parts of the West Coast, affecting communities like Cambridge, Oakland, Miami, St. Petersburg, Galveston, Houston, New Orleans and all five boroughs of New York City.

Granted, for many people in these areas, strong storms and flooding have been a fact of life for a long, long time. The question is, however, at what point does chronic flooding become intolerable? How many times can vehicles be destroyed or houses be damaged by first-floor flooding? How long can things be disrupted before properties become uninsurable and possibly un-sellable?

Just consider that, if sea level rise goes unchecked, this type of flooding could swallow up the Jersey shore, the South Carolina low country, North Carolina’s Pamlico Sound, the Chesapeake and Tidewater areas of Virginia and possibly all of New Orleans.

Colorado Sea Level Studies 

Some of the most intensive and well-researched studies in global sea level rise maps have come from the University of Colorado. Since 1993, they have used a system of satellite radar altimeters to gauge global mean sea level, then taken these measurements in context with a network of tide gauges. After figuring in seasonal variations, they’re able to arrive at a global mean sea level rate.

Their empirical data showed that in the 90s, there were reductions in heat content in the oceans, believed to be linked to the 1991 eruption of Mt. Pinatubo. Despite that dip, heat content has been accelerating and is likely to continue to accelerate over the next decade.

Their map and models show a worrisome trend, with a great deal of vulnerability along the Atlantic coast. Researchers have pointed to an El Nino meteorological pattern and shifts in atmospheric pressure over the ocean, but others have noted a direct tie-in between melting Antarctic ice sheets, heat-trapping greenhouse pollution and rising sea levels.

The Bottom Line 

Between now and 2050, global average sea level is expected to rise by one foot, and possibly by several more feet by the century’s end if greenhouse gas emissions go unchecked. That would undoubtedly mean a map of the United States that looks very different than how it looks today. On the other hand, if action is taken soon to curb greenhouse gases, sea level rise could be limited to less than two feet.

Even under the latter scenario, it would mean nearly two million Americans exposed to risk from flooding and inundation by the year 2100. In Bangladesh, that would mean eight million people, with nearly 12 million in Vietnam and 27 million in China being exposed to chronic, catastrophic flooding. In the worst-case scenario, it could mean as many as 153 million people worldwide being permanently inundated and forced to relocate inland.

It’s important to remember that the science and statistics on global warming sea level rise maps are still incomplete and subject to debate. As research methodology and models continue to improve, the numbers and projections are likely to change, making it difficult to assign probabilities to these outcomes. For instance, earlier models from the 90s didn’t take into account the rate at which the polar ice caps and glaciers are melting. Still, the information that’s available now points toward trends and median values that are all pretty alarming.  The good news is that this research also points the way toward steps that can be taken to mitigate a devastating rise in sea levels before it’s too late.