A study of coral beds off the Texas coast suggests sea level rise as a result of climate change may not proceed in a slow and steady fashion over centuries—but may come in bursts of several metres of vertical rise over a matter of just a few decades.
The faster timeline would challenge most cities’ ability to adapt infrastructure and land development to sea levels that could be metres higher—and reach many kilometres further inland—by the end of the facilities’ planned life than when they were designed.
The study, published this week in Nature Communications, suggests that at the end of the last ice age between 12,000 and 14,000 years ago, “water rose rapidly, in punctuated bursts, rather than gradually over time, likely driven by uneven pulses of meltwater from the world’s collapsing glaciers,” writes E&E News [subs req’d], in a report republished by Scientific American.
Sampling long-dead coral that grew in what is now deep water off the coast of Texas, researchers identified “fossil reefs arranged in a series of six stair-like shelves, or terraces—a classic signal of past sea level rise,” the news outlets report. The spacing and height of the terraces “suggest several metres of sea level rise may have occurred on the scale of just decades during this time.”
“It opens up the door to this possibility that as ice sheets retreat quickly, maybe they do so in a stepwise fashion,” said Andrea Dutton, a paleo-climatologist at the University of Florida who did not participate in the research. She cautioned, however, that “it’s not clear the mechanisms will be exactly the same” in the current round of global warming triggered by human releases of greenhouse gases. “That’s something to be determined.”
Even without such sudden bursts of rapidly rising ocean, scientists have warned that incremental increases in sea level could displace more than 13 million people in the United States alone by 2100, incurring relocation costs of US$14 trillion.