Half of the world's beaches could disappear by the end of this century as a result of climate change-induced coastal erosion and rising seas, according to a study published Monday in thejournal Nature Climate Change.
As global temperatures continue to rise, driven by emissions of heat-trapping greenhouse gases, melting ice will raise sea levels and extreme weather events are expected to become more frequent and intensify, battering vulnerable coastlines around the world, according to the researchers at the European Union's Joint Research Centre in Ispra, Italy. If these processes are left unchecked, it could result in the "near extinction" of 50 percent of the globe's sandy beaches by the year 2100, they said.
The scientists used satellite images to measure how coastlines have evolved over the past 30 years. They then used various projections of sea level rise to model how beaches and shores could be affected in the future.
According to the U.N. Intergovernmental Panel on Climate Change, average global sea levels could rise by 0.95 feet to 3.61 feet by the end of this century.
But the researchers found that the severity of damage to the world's sandy beaches, which occupy more than one-third of global coastlines, was dependent on how much the global temperatures could rise, making the rate of greenhouse gas emissions a major factor.
"If you consider that in a high-emissions scenario, the expected sea level rise is around 80 centimeters [almost 3 feet], then it's not that surprising," said Michalis Vousdoukas, a coastal oceanography researcher at the Joint Research Centre and the lead author of the new study.
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Vousdoukas said most of the world's coastlines are already eroding, but parts of North Africa, Central America, West Africa, northern Australia and small island nations could be among the most at risk.
"A substantial proportion of the threatened sandy shorelines are in densely populated areas, underlining the need for the design and implementation of effective adaptive measures," the researchers wrote in the study.
The loss of beaches has important cultural and economic implications for countries, but there are also ecological concerns, according to Vousdoukas.
"Beaches are like the last barrier that protects inland areas from storms because they absorb energy from waves," he said, adding that many beaches host organisms that also contribute to an ecosystem's biodiversity.
Robert Young, director of the Program for the Study of Developed Shorelines at Western Carolina University in Cullowhee, North Carolina, said the findings are important, but that many beaches around the world are already in peril.
"There are probably hundreds of kilometers of the world's beaches that have already disappeared," said Young, who was not involved with the new research. "Places like South Beach in Miami, Myrtle Beach in South Carolina, Virginia Beach — there's really not a natural grain of sand left on them. They've already disappeared, but we keep them there by pumping in artificial sand."
This process, known as beach nourishment, involves transporting sand and other sediments from inland to replace what's lost along shorelines due to erosion.
Some degree of coastal erosion is natural, and shorelines have been constantly changing throughout history. But Young said climate change will wreak havoc along waterfronts that have been heavily developed, particularly if the effects of global warming outpace a community's ability to either relocate or build up resilience.
"Some 15,000 years ago, at the end of the last ice age, sea levels were 120 meters lower and all our beaches were miles offshore," he said. "They've now moved to where they are now, but when you put something in the way of that movement — houses, seawalls, hotels — then the beach is trying to move but we're expecting the shoreline to stay in place."
Vousdoukas and his colleagues did not outline specific solutions in their research, but emphasized that reducing greenhouse gas emissions will likely be an important factor. In the study, the authors estimate that up to 40 percent of beach erosion could be prevented by limiting global warming to 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, as is targeted by the Paris Agreement.