Will we lose all our beaches underwater as sea levels rise? Won’t it take years for new beaches to form?
In: Earth Science
We will lose a lot of our beaches, despite what many people on here seem to think. If the coastline was a gently rising plane of substrate the sand could continue moving inland as the seas rises, preserving a beach at the edge of the water, but this simply isnt the case.
Large waves breaking hear shore in shallow water tend to remove sand from beaches and drag it off shore. Increasing storm frequency is leading to more of these large wave events that remove sand. This will shift the balance in many places from beach formation to beach erosion.
Sand gets deposited when breaking waves can slow as they run up a gentle slope, allowing the sand to settle out. In order to protect coastline development, we build sea walls and other barriers that prevent this, causing the waves that break into them to scour more sand and preventing sand from being deposited inland. On the west coast, many of the beaches are narrow and end at the base of cliffs. Sea level rise will reduce the width of the beach even further, making the cliffs into seawalls, regularly being hit by breaking waves, which will remove the rest of the beach. For example, I used to live near [this beach.](https://i1.wp.com/southocbeaches.com/wp-content/uploads/2016/12/strands-beach-march-8-2016-by-southocbeaches-com.jpg?resize=656%2C492&ssl=1) Then they built a housing development by terracing the cliff, put up a rock sea wall about 20 feet closer to the beach than the base of the cliff was, and within two years the sand along a large stretch that was closer to the high tide line was gone for much of the year, hence the walkway along the top of the wall.
Barrier islands and wetlands absorb storm energy and reduce flooding, while being a source of new sand. We are paving wetlands and barrier islands. In addition, when barrier island are topped by storm surge, they can rapidly be eroded away. Sea level rise couple with increasing storm frequency will make this more common.
Finally, increased inland flooding will pollute water and fill it with trash. Increased nutrient pollution tips the balance of the near shore scosystem towards blooms of toxic algae and increased jellyfish population. This will reduce the quality of beaches, even if the sand remains.
If you’re a young adult, by the time you retire your favorite beach will likely not be a place that you will find enjoyable to spend time at, if it exists at all.
In a lecture I attended by Neil deGrasse Tyson, he stated in a opinion/analogy that global warming really won’t be tackled until the beach resorts of the ultra-wealthy are endangered. Until then inaction would be paramount.
So, there are plenty of sources of beach or shore erosion that are exacerbated by sea-level rise.
If you’re slowly losing land in a river estuary due to channelization, dredging, loss of silt and so on sea level rise will accelerate that. Large chunks of the gulf coast particularly Louisiana are experiencing this.
Construction of sea walls and other barriers concentrates the energy of wave action and shifts it around so the places that didn’t previously experience flooding or pounding surf now do. This is implicated in significant damage to New York and Long Island during hurricanes. New sea walls means you old flood surveys and models no longer work in dramatic ways which make planning hard.
Low lying barrier islands may no longer provide the shore with as much protection as the did previous thereby increasing erosion in places not previously prone to it. Barrier islands in the Carolinas Texas and Florida are being less effective over time.
It’s not so much that we lose beaches entirely though we do lose some, it’s more that we lose our current shoreline, the built environment that assumes the old boundaries, the habitat along our shores, and a lot of low lying islands including inhabited ones. Places like Kiribati or costal Bangladesh aren’t going to be inhabitable.
Ideally, no, the rates are slow enough that the beaches will migrate with the change in sea level. There are situations where we humans have developed the near back-shore zone where the beaches ought to migrate if/when water rises, but the presence of human infrastructure will interfere with the natural migration. People won’t be all that complacent about beaches migrating onto their property (or later, the ocean migrating onto their property).
It is possible, likely even in many places, that the beaches will relocate laterally (like if there are rocky headlands that won’t allow sand accumulation, the sand will migrate downshore somewhere). These sorts of things already happen.
Some beaches and barrier islands will get lost and become off-shore bars rather than beaches, but how each and every situation will modify in response to changing sea level is very much dependent on the specific circumstances of the location.
There is a story a read where a beach disappeared overnight due to change in currents or a storm. And then years later it reappeared when another storm or hurricane came in.
The forming of the sand takes ages but the tides and currents and storms can move sand beds very quickly.so as the oceans rise the beaches will just be pushed inland most likely.
There’s no one answer-in some cases we’ll lose beaches, in some cases the beaches will move higher than before, in some cases conservation efforts to save them will work and the original beaches will be protected. Overall though, yes, there will be a large loss of beach ecosystems as beaches do take years to form.
You won’t have to worry. We are going into a grand solar minimum in the next few years and it will last for decades, cooling the earth.
Beaches in urban areas that are delimited by streets with buildings and roads are probably going to disappear unless those streets are removed
No. Disease, famine, and extreme weather events will kill most of us decades before our beaches recede in any noticeable way
Many beaches have sand that’s been dredged. Some communities will be able to move more sand where it’s needed, but others won’t have the resources to do that.
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