How three coastal communities are dealing with rising seas | Science News for Students

How three coastal communities are dealing with rising seas

There are many ways to react when the ocean encroaches
Jan 10, 2019 — 6:20 am EST
a photo at water level showing beachhomes on stilts next to the incoming ocean water

The beach that used to be in front of these North Carolina homes has eroded away. Such land loss can eventually undermine and destroy the buildings.

summersetretrievers/iStockphoto

Around the world, rising seas pose a major threat to coastal communities. Flooding will likely become worse, damaging buildings where people live and work. People who reside near the ocean have to change the way they live and build, or get out altogether. Here are how a few coastal communities are facing climate change by adapting to the new normal.

Losing ground in the “Venice of Africa”

People who live in Saint-Louis are in a daily race against the sea. Saint-Louis is in Senegal, on the west coast of Africa. It’s near where the Senegal River meets the Atlantic Ocean. The seaside city has a rich culture and history. Some people call this place the “Venice of Africa.” (Venice is an Italian city famous for its canals and culture.)

Climate change, however, is putting Saint-Louis in a precarious position. Rising seas and land erosion are bringing the ocean into the city. In 2008, an official with the United Nations called Saint-Louis “the African city most threatened by the rising levels of the sea.” He said this during a conference at a university in Saint-Louis.

On average, Senegal loses a meter (3.3 feet) or more of coastline every day! The encroaching water brings salt water inland. This makes the Senegal River more salty, and its fish have to swim farther upstream for fresh water. Salt water can also poison crops and trees on land. Small fishing villages near Saint-Louis have already vanished. People have left their homes and work behind to move away from the water.

In December 2017, the mayor of Saint-Louis asked other countries for help. The World Bank, which loans money to poor countries at low or no interest rates, provided $30 million in credit. This loan is designed to help the city find new ways to protect itself from the sea and to help the people of Saint-Louis who have had to flee their homes.

Repair, replenish, rebuild, repeat

Every year, thousands of beach-seeking tourists visit the U.S. Outer Banks. This narrow strip of sandy islands sits off the coast of North Carolina. These barrier islands naturally shift to the west as storms erode the shore and blow sand toward the coast.

Climate change is speeding this process. It’s also causing sea level to rise. A study published in August 2017 found that the ocean is rising about 2.5 centimeters (1 inch) per year along some parts of the U.S. East Coast. That’s faster than previous studies had predicted. Higher water levels wash away more sand, boosting erosion. Some homes have collapsed or been demolished as the rising water erodes away the sand beneath them.

Every year, the ocean takes away about 2 meters (6 feet) from the beaches of Nags Head, a popular tourist destination. Some beaches lose 3 meters. The city’s response has been to fight back. The government has hired construction firms to move sand from the ocean floor to the beach. This process is called “nourishing.” But it’s very expensive. Climate scientists also say it’s futile. 

An artificial island in a tropical paradise

Hulhumalé is being constructed as a place that’s resilient to climate change. It’s already unusual. The artificial island is part of the Maldives. This tropical nation in the Indian Ocean includes 26 atolls. (An atoll is a ring-shaped formation made of coral.) Atolls in the Maldives are made from thousands of coral islands.

Most land in the Maldives sits less than one meter (3.3 feet) above sea level. The highest natural point, atop a dune, is only 2.4 meters (about 8 feet) high. The Maldives is vulnerable to flooding or being washed away altogether. Computer models predict that sea level may rise by 50 centimeters (1.5 feet) within the next 80 years. If that happens, and nothing changes, nearly 80 percent of the land in the Maldives will disappear beneath the surface.

People in the Maldives are looking for solutions through geoengineering. That involves physically changing the land itself. Engineers created Hulhumalé by moving sand from the sea floor to higher ground. Its walls are being built 3 meters above sea level. The Maldives’ government plans to be done with construction in about five years. By then, the island’s sole city may provide homes to more than 100,000 people.

This video highlights the threat of sea level rise to low-lying island nations in the Pacific Ocean.
Conservation International/YouTube

Power Words

(more about Power Words)

Atlantic     One of the world’s five oceans, it is second in size only to the Pacific. It separates Europe and Africa to the east from North and South America to the west.

atoll     A ring-shaped island formed from a coral reef that surrounds a lagoon.

average     (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

barrier island     A low, narrow, sandy island that develops just off the coast.

climate     The weather conditions that typically exist in one area, in general, or over a long period.

climate change     Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.

computer model     A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event.

coral     Marine animals that often produce a hard and stony exoskeleton and tend to live on reefs (the exoskeletons of dead ancestor corals).

crop     (in agriculture) A type of plant grown intentionally grown and nurtured by farmers, such as corn, coffee or tomatoes. Or the term could apply to the part of the plant harvested and sold by farmers. 

culture     (n. in social science) The sum total of typical behaviors and social practices of a related group of people (such as a tribe or nation). Their culture includes their beliefs, values and the symbols that they accept and/or use. Culture is passed on from generation to generation through learning. Scientists once thought culture to be exclusive to humans. Now they recognize some other animals show signs of culture as well, including dolphins and primates.

engineer     A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.

erode     Gradual removal of soil or stone, caused by the flow of water or the movement of winds.

erosion     (v. erode) The process that removes rock and soil from one spot on Earth’s surface, depositing it elsewhere. Erosion can be exceptionally fast or exceedingly slow. Causes of erosion include wind, water (including rainfall and floods), the scouring action of glaciers and the repeated cycles of freezing and thawing that occur in many areas of the world.

model     A simulation of a real-world event (usually using a computer) that has been developed to predict one or more likely outcomes. Or an individual that is meant to display how something would work in or look on others.

resilient     (n. resilience) To be able to recover fairly quickly from obstacles or difficult conditions. (in materials) The ability of something to spring back or recover to its original shape after bending or otherwise contorting the material.

sea     An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.

sea level     The overall level of the ocean over the entire globe when all tides and other short-term changes are averaged out.

upstream     The direction from which water flows, or portions of a stream from which water has flowed.

Citation

Journal:​ M. Esteban et al. Adaptation to sea level rise on low coral islands: Lessons from recent events. Ocean & Coastal Management. Vol. 168, February 2019, p. 35. doi: 10.1016/j.ocecoaman.2018.10.031.

Journal:​ ​​ T. Vedeld et al. Climate adaptation at what scale? Multi-level governance, resilience, and coproduction in Saint Louis, Senegal. Natural Hazards. Vol. 82, June 2016, p. 173. doi: 10.1007/s11069-015-1875-7.

Sponsor