1 00:00:02,040 --> 00:00:07,040 Speaker 1: Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff, 2 00:00:07,080 --> 00:00:10,479 Speaker 1: Lauren Vogel bomb Here in summer, there's nothing like feeling 3 00:00:10,480 --> 00:00:12,840 Speaker 1: the sun on your face and the sand between your toes. 4 00:00:13,400 --> 00:00:16,960 Speaker 1: But the rising sea levels and stronger coastal storms associated 5 00:00:17,000 --> 00:00:19,520 Speaker 1: with climate change pose a threat to the sands that 6 00:00:19,560 --> 00:00:22,720 Speaker 1: make up our beaches. A common approach to combating erosion 7 00:00:22,760 --> 00:00:26,040 Speaker 1: at u S coastlines is beach nourishment, which is literally 8 00:00:26,120 --> 00:00:28,760 Speaker 1: taking sand from one place off and off shore and 9 00:00:28,800 --> 00:00:32,760 Speaker 1: pumping it onto a sand depleted beach. The question is, 10 00:00:33,000 --> 00:00:36,240 Speaker 1: can beach nourishment keep up with the ever increasing forces 11 00:00:36,240 --> 00:00:39,680 Speaker 1: of climate change, or, like Sisyphus forever pushing his boulder 12 00:00:39,720 --> 00:00:42,640 Speaker 1: up the hill, is adding sand to beaches an expensive, 13 00:00:42,840 --> 00:00:46,519 Speaker 1: temporary fix to a long term problem. We spoke with 14 00:00:46,600 --> 00:00:50,120 Speaker 1: Bonnie Lutka, a post doc at Scripps Institution of Oceanography 15 00:00:50,159 --> 00:00:53,480 Speaker 1: at the University of California in San Diego. She said, 16 00:00:53,880 --> 00:00:56,400 Speaker 1: I think there's reason to be concerned, but I also 17 00:00:56,440 --> 00:00:58,720 Speaker 1: think there's still a lot we don't know about how 18 00:00:58,760 --> 00:01:01,680 Speaker 1: long the sand stays where it goes, and how much 19 00:01:01,720 --> 00:01:04,120 Speaker 1: sand you need to place on a beach to be effective, 20 00:01:04,560 --> 00:01:08,000 Speaker 1: or learning as we go. A study published by Luca 21 00:01:08,080 --> 00:01:11,880 Speaker 1: in the June issue of the journal Coastal Engineering examines 22 00:01:11,959 --> 00:01:15,039 Speaker 1: exactly what happened to sand deposited on four beaches in 23 00:01:15,080 --> 00:01:18,720 Speaker 1: San Diego County in California. She and her colleagues used 24 00:01:18,800 --> 00:01:21,000 Speaker 1: jet skis, a t v s, and other tools to 25 00:01:21,080 --> 00:01:24,400 Speaker 1: continuously monitor sand levels and sand movement at the beaches 26 00:01:24,680 --> 00:01:27,800 Speaker 1: over a period of about ten years. The research received 27 00:01:27,800 --> 00:01:30,240 Speaker 1: funding from the U. S. Army Corps of Engineers, the 28 00:01:30,319 --> 00:01:33,920 Speaker 1: California Department of Parks and Recreation, the National Science Foundation, 29 00:01:34,120 --> 00:01:37,839 Speaker 1: and the California Sea Grant. Among their findings, the team 30 00:01:37,920 --> 00:01:40,360 Speaker 1: learned that the entire amount of sand added to San 31 00:01:40,360 --> 00:01:43,440 Speaker 1: Diego's Tory Pines in two thousand one was washed away 32 00:01:43,480 --> 00:01:46,840 Speaker 1: during a single storm. At another beach, the addition of 33 00:01:46,840 --> 00:01:49,480 Speaker 1: a hundred and thirty eight Olympic swimming pools worth of 34 00:01:49,480 --> 00:01:52,560 Speaker 1: sand contributed to the clogging and eventual closure of a 35 00:01:52,600 --> 00:01:56,680 Speaker 1: nearby estuary. Among the team's more positive findings was that 36 00:01:56,840 --> 00:01:59,640 Speaker 1: larger grained sand appeared to have better staying power than 37 00:01:59,720 --> 00:02:03,080 Speaker 1: fine grained sand, and in some cases, the amount of 38 00:02:03,080 --> 00:02:06,360 Speaker 1: sand deposited to a beach by natural forces was comparable 39 00:02:06,440 --> 00:02:10,880 Speaker 1: to any mechanically added sand Luca said, there is quite 40 00:02:10,880 --> 00:02:13,359 Speaker 1: a bit of natural variability, so it's hard to pick 41 00:02:13,360 --> 00:02:16,200 Speaker 1: out trends, but at our longest recorded site, we did 42 00:02:16,280 --> 00:02:20,400 Speaker 1: see an overall pattern of erosion. The pattern of erosion 43 00:02:20,400 --> 00:02:23,280 Speaker 1: that Luca's team observed at ground level is what's alarming 44 00:02:23,320 --> 00:02:26,600 Speaker 1: to researchers assessing the long term future of US beaches. 45 00:02:27,520 --> 00:02:30,119 Speaker 1: With climate change, sea level has risen by about eight 46 00:02:30,160 --> 00:02:34,560 Speaker 1: inches that's twenty since nine, according to the Intergovernmental Panel 47 00:02:34,600 --> 00:02:37,480 Speaker 1: on Climate Change, and could rise three to five feet 48 00:02:37,560 --> 00:02:40,399 Speaker 1: higher that's point nine to one point five meters by 49 00:02:40,440 --> 00:02:43,960 Speaker 1: the end of this century. More frequent coastal storms, also 50 00:02:44,000 --> 00:02:47,120 Speaker 1: associated with climate change, take a further toll on beaches 51 00:02:47,160 --> 00:02:49,760 Speaker 1: by unleashing rough waves that eat away at the shore. 52 00:02:50,720 --> 00:02:53,440 Speaker 1: We also spoke with Michael or Back, Professor Emeritus of 53 00:02:53,480 --> 00:02:57,320 Speaker 1: Marine Affairs and Policy at Duke University. He said, any 54 00:02:57,360 --> 00:03:00,840 Speaker 1: beach nourishment is forever. It's like painting house. Once you 55 00:03:00,919 --> 00:03:03,760 Speaker 1: start it, you have to keep doing it forever to maintain. 56 00:03:04,400 --> 00:03:06,919 Speaker 1: The problem is with climate change, in rising sea levels, 57 00:03:07,080 --> 00:03:09,640 Speaker 1: there's going to be even more demand by orders of 58 00:03:09,680 --> 00:03:13,320 Speaker 1: magnitude because the beaches are going to erode more and faster. 59 00:03:14,040 --> 00:03:17,560 Speaker 1: Western Carolina University's Program for the Study of Developed Shorelines 60 00:03:17,680 --> 00:03:20,920 Speaker 1: hosts an interactive database of beach nourishment projects across the 61 00:03:21,000 --> 00:03:25,000 Speaker 1: US and their costs. As the data show, beach nourishment 62 00:03:25,040 --> 00:03:28,560 Speaker 1: today is not cheap. Or Bach estimates the average cost 63 00:03:28,639 --> 00:03:31,560 Speaker 1: of supplementing sand at beaches comes out between one and 64 00:03:31,639 --> 00:03:35,400 Speaker 1: two million dollars per mile of sand. As the demand 65 00:03:35,440 --> 00:03:38,440 Speaker 1: for sand four beach nourishment increases, the cost will rise 66 00:03:38,480 --> 00:03:41,520 Speaker 1: even higher. Or Bach predicts. He said, in the end, 67 00:03:41,640 --> 00:03:44,720 Speaker 1: there may not be enough sand that's economically recoverable to 68 00:03:44,840 --> 00:03:48,360 Speaker 1: nourish every beach that people want to nourish. There's also 69 00:03:48,400 --> 00:03:51,840 Speaker 1: an ecological cost. Studies have shown that dredging and depositing 70 00:03:51,880 --> 00:03:54,480 Speaker 1: sand is disruptive to creatures living in the sand and 71 00:03:54,640 --> 00:03:57,839 Speaker 1: the animals that eat them. While the research suggests those 72 00:03:57,880 --> 00:04:00,680 Speaker 1: animals tend to recover after eighteen months to two years, 73 00:04:01,000 --> 00:04:04,440 Speaker 1: beaches that undergo repeated nourishment to see significant declines in 74 00:04:04,480 --> 00:04:09,640 Speaker 1: animal life. Despite the economic and ecological costs of beach nourishment, 75 00:04:09,880 --> 00:04:12,640 Speaker 1: it may be among the few available options for preserving 76 00:04:12,680 --> 00:04:16,720 Speaker 1: beaches in the future. Sean Vita, sec and engineer specializing 77 00:04:16,760 --> 00:04:19,640 Speaker 1: in ocean modeling at the University of Illinois and Chicago 78 00:04:19,960 --> 00:04:23,159 Speaker 1: points out that natural sources of beach sand, including rivers 79 00:04:23,160 --> 00:04:26,200 Speaker 1: and eroding cliffs, have been suppressed by human built dams 80 00:04:26,200 --> 00:04:29,760 Speaker 1: and protective coverings. Vita Sex served as lead author of 81 00:04:29,760 --> 00:04:33,320 Speaker 1: a March seventeen modeling analysis from the U S Geological 82 00:04:33,320 --> 00:04:36,480 Speaker 1: Survey that concluded that if no measures are taken, up 83 00:04:36,480 --> 00:04:39,880 Speaker 1: to sixty seven percent of California's beaches could be completely 84 00:04:39,920 --> 00:04:43,000 Speaker 1: eroded back to sea, cliffs or coastal infrastructure by the 85 00:04:43,080 --> 00:04:47,040 Speaker 1: year twenty one hundred. The U S Geological Survey models 86 00:04:47,080 --> 00:04:49,839 Speaker 1: showed that beach nourishment could protect some larger beaches that 87 00:04:49,880 --> 00:04:53,640 Speaker 1: have undergone nourishment for decades, but that overall beach nourishment 88 00:04:53,640 --> 00:04:55,640 Speaker 1: will have to be stepped up to a much faster 89 00:04:55,720 --> 00:04:59,200 Speaker 1: pace to continue to be at all effective. Vita Sex said, 90 00:04:59,560 --> 00:05:01,839 Speaker 1: if you dump sand on a beach, that sand is 91 00:05:01,880 --> 00:05:04,800 Speaker 1: not going to stay there forever, the current methodical rate 92 00:05:04,839 --> 00:05:08,440 Speaker 1: of beach nourishment is insufficient against the coming sea level rise. 93 00:05:09,560 --> 00:05:12,640 Speaker 1: Ludca said there is quite some debate about how climate 94 00:05:12,720 --> 00:05:15,960 Speaker 1: change will influence the frequency and intensity of storms, and 95 00:05:16,000 --> 00:05:18,920 Speaker 1: these storms will be more responsible for beach evolution than 96 00:05:19,040 --> 00:05:22,400 Speaker 1: sea level rise in the next few decades. It may become, 97 00:05:22,480 --> 00:05:25,279 Speaker 1: she says, a matter of choosing between investing in ever 98 00:05:25,400 --> 00:05:28,760 Speaker 1: pricier efforts to preserve beaches or standing back and allowing 99 00:05:28,800 --> 00:05:31,680 Speaker 1: nature's forces to redraw the lines of where the ocean 100 00:05:31,839 --> 00:05:39,640 Speaker 1: meets the land. Today's episode was written by Amanda Onion 101 00:05:39,680 --> 00:05:42,240 Speaker 1: and produced by Tyler Clang. For more on this and 102 00:05:42,400 --> 00:05:46,000 Speaker 1: lots of other alarming but important topics, visit our home planet, 103 00:05:46,120 --> 00:05:58,640 Speaker 1: how stuff Works dot com.