Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff, Lauren Vogel bomb Here in summer, there's nothing like feeling the sun on your face and the sand between your toes. But the rising sea levels and stronger coastal storms associated with climate change pose a threat to the sands that make up our beaches. A common approach to combating erosion at u S coastlines is beach nourishment, which is literally taking sand from one place off and off shore and
pumping it onto a sand depleted beach. The question is, can beach nourishment keep up with the ever increasing forces of climate change, or, like Sisyphus forever pushing his boulder up the hill, is adding sand to beaches an expensive, temporary fix to a long term problem. We spoke with Bonnie Lutka, a post doc at Scripps Institution of Oceanography
at the University of California in San Diego. She said, I think there's reason to be concerned, but I also think there's still a lot we don't know about how long the sand stays where it goes, and how much sand you need to place on a beach to be effective, or learning as we go. A study published by Luca in the June issue of the journal Coastal Engineering examines exactly what happened to sand deposited on four beaches in
San Diego County in California. She and her colleagues used jet skis, a t v s, and other tools to continuously monitor sand levels and sand movement at the beaches over a period of about ten years. The research received funding from the U. S. Army Corps of Engineers, the California Department of Parks and Recreation, the National Science Foundation,
and the California Sea Grant. Among their findings, the team learned that the entire amount of sand added to San Diego's Tory Pines in two thousand one was washed away during a single storm. At another beach, the addition of a hundred and thirty eight Olympic swimming pools worth of sand contributed to the clogging and eventual closure of a
nearby estuary. Among the team's more positive findings was that larger grained sand appeared to have better staying power than fine grained sand, and in some cases, the amount of sand deposited to a beach by natural forces was comparable to any mechanically added sand Luca said, there is quite a bit of natural variability, so it's hard to pick out trends, but at our longest recorded site, we did
see an overall pattern of erosion. The pattern of erosion that Luca's team observed at ground level is what's alarming to researchers assessing the long term future of US beaches. With climate change, sea level has risen by about eight inches that's twenty since nine, according to the Intergovernmental Panel on Climate Change, and could rise three to five feet higher that's point nine to one point five meters by
the end of this century. More frequent coastal storms, also associated with climate change, take a further toll on beaches by unleashing rough waves that eat away at the shore. We also spoke with Michael or Back, Professor Emeritus of Marine Affairs and Policy at Duke University. He said, any beach nourishment is forever. It's like painting house. Once you start it, you have to keep doing it forever to maintain.
The problem is with climate change, in rising sea levels, there's going to be even more demand by orders of magnitude because the beaches are going to erode more and faster. Western Carolina University's Program for the Study of Developed Shorelines hosts an interactive database of beach nourishment projects across the US and their costs. As the data show, beach nourishment today is not cheap. Or Bach estimates the average cost of supplementing sand at beaches comes out between one and
two million dollars per mile of sand. As the demand for sand four beach nourishment increases, the cost will rise even higher. Or Bach predicts. He said, in the end, there may not be enough sand that's economically recoverable to nourish every beach that people want to nourish. There's also an ecological cost. Studies have shown that dredging and depositing sand is disruptive to creatures living in the sand and
the animals that eat them. While the research suggests those animals tend to recover after eighteen months to two years, beaches that undergo repeated nourishment to see significant declines in animal life. Despite the economic and ecological costs of beach nourishment, it may be among the few available options for preserving
beaches in the future. Sean Vita, sec and engineer specializing in ocean modeling at the University of Illinois and Chicago points out that natural sources of beach sand, including rivers and eroding cliffs, have been suppressed by human built dams
and protective coverings. Vita Sex served as lead author of a March seventeen modeling analysis from the U S Geological Survey that concluded that if no measures are taken, up to sixty seven percent of California's beaches could be completely eroded back to sea, cliffs or coastal infrastructure by the
year twenty one hundred. The U S Geological Survey models showed that beach nourishment could protect some larger beaches that have undergone nourishment for decades, but that overall beach nourishment will have to be stepped up to a much faster pace to continue to be at all effective. Vita Sex said, if you dump sand on a beach, that sand is not going to stay there forever, the current methodical rate of beach nourishment is insufficient against the coming sea level rise.
Ludca said there is quite some debate about how climate change will influence the frequency and intensity of storms, and these storms will be more responsible for beach evolution than sea level rise in the next few decades. It may become, she says, a matter of choosing between investing in ever pricier efforts to preserve beaches or standing back and allowing nature's forces to redraw the lines of where the ocean meets the land. Today's episode was written by Amanda Onion
and produced by Tyler Clang. For more on this and lots of other alarming but important topics, visit our home planet, how stuff Works dot com.