Scientific Visuals: Land Loss due to Sea Level Rise
As climate change heats up the world, coastlines and communities are impacted by rising sea levels. Melting ice caps and the thermal expansion of water raise the level, eroding shorelines and causing increasing storm surges and inland flooding. Communities living on the coast, particularly of small island countries, face threats to their homes and livelihoods with the unprecedented rate of sea level rise.
A variety of visuals can be used to present this scientific topic and show not only the statistical facts of what is happening but the impacts on people and the land.
Rising Sea Level
Throughout history, the global sea level has risen and fallen multiple times due to environmental shifts such as ice ages and warming periods, says the World Economic Forum. However, the current rate and speed of which the water is rising has never been seen before and holds drastic ramifications for countries all over the world.
Satellites are used to measured the sea level with radar signals. This graph by NASA is a line chart used to clearly show an increase over time. As Bill Dennison explains in his article Practical Visual Literacy for Science Communication, “A variety of different graphing styles (e.g., line, bar, stacked bar, pie, two dimensional, three dimensional) can be used to display data” in scientific communication and “Different graph styles can be selected for different data types” (Dennison).
The chart is clearly labeled and clean. It uses greenish shades for the data with a dark line for the average and a lighter color for high and low points. A red dot shows location of present time. The graph also has a large number in the top corner that provides a summary of the information at a glance. According to this, since 1993 the sea has risen by 100 millimeters or 10 centimeters. Though this seems like a miniscule amount of change, small disruptions can have major effects. In addition, 10 cm on a global scale differs from changes on a regional scale; WEF says that “relative sea level rise can vary significantly depending on local factors such as land subsidence and ocean currents” (WEForum).
Coastal Erosion
Nature exists through a series of cycles that deplete and restore nutrients and resources over time. Human activity has interrupted these cycles, preventing natural areas from replenishing themselves.
Beaches are formed by wind and water breaking down parts of land into rocks and eroding them into sand. The tide pulls sand away but also comes in and deposits new sediment. National Geographic says that the season affects the size and shape of beaches as well. They explain, “During the winter, storm winds toss sand into the air. This can sometimes erode beaches and create sandbars […] During the summer, waves retrieve sand from sandbars and build the beach back up again. These seasonal changes cause beaches to be wider and have a gentle slope in the summer, and be narrower and steeper in the winter” (National Geographic).
This diagram by LibreTexts shows the shape change of beaches during different seasons. It has simple labels that provide the basic information necessary without overcrowding. It also uses shades of blue to show the depth of the water and textures to highlight and differentiate the rock from the sand.
Although beaches change over time, due to human interference, they are not allowed to do so naturally. Dams prevent river sediment from being added to beaches, causing them to recede. Beachfront buildings and houses impact the shore and lead to the creation of structures like seawalls.
These photographs from 2008 and 2021 of San Clemente, California demonstrate the devastating change due to erosion by providing a direct comparison.
This effect can be amplified with the use of movement; Geoscience Australia used satellite images to create GIFs that showcase the gradual but steady retreat of the coastline from 1988 to 2019.
The use of motion catches attention and emphasizes the fact that significant change has occurred over time.
Impacts
Many groups of people are especially vulnerable to the loss of coastline. Those who depend on shoreline-related revenues like “tourism, fishing, and agriculture” (WEForum) face threats to their livelihood while others are pushed out of their homes.
Small island nations are at risk of being swallowed by the ocean entirely. Tuvalu is a tiny chain of nine islands between Hawaii and Australia. It has a population of only 11,000 people who mainly live on the largest island, Fongafale.
A photo of Tuvalu and its main island shows how small it truly is. Seeing the scale of the houses and land to the surrounding ocean puts into perspective how vulnerable they are to a rising sea level.
What Do We Do?
To protect buildings and infrastructure, various methods have been used and explored to rebuild beaches and reduce storm damage.
Seawalls are commonly built to block waves from crashing into beachside buildings and houses. However, they may prevent sand from being transported to other areas, reducing the size of those beaches. They may also increase erosion instead; National Geographic says, “When tides and waves hit massive seawalls instead of beaches, they bounce back to the ocean with more energy. This tidal energy causes the sand in front of a seawall to erode much more quickly than it would without the seawall” (National Geographic). This seawall graphic displays the long-term effect with a simple step-by-step format.
Other places rely on artificially replacing sand. Beach replenishment or beach nourishment is the act of taking sand dredged from offshore and bringing it back to the beach. This temporarily restores the beach until the sand is washed away once more. According to Explore Beaches, this kind of flexible “soft armoring” method is preferable to a “hard armoring” one like seawalls. The unmoving nature of seawalls means that waves are not allowed in and the beach eventually fully disappears. With nourishment, the original beach is preserved.
There are consequences to this method too, though. For one, it requires heavy machinery to place the new sand. Second, the new sand must match the existing sand in size and composition to not affect the ecosystem. Finally, the disturbance to animals and habitats can be great and cause lasting damage (Explore Beaches).
Managed Retreat
Besides the much larger changes to how humans are impacting the climate, what can be done to address the disappearing beaches?
One concept is called managed retreat. This is the movement of buildings further inland to allow room for the ocean to interact with the land. Rather than fight the waves, the idea is to give them space to do what they naturally will.
Sources:
Australia, Geoscience. “Satellite Imagery Reveals Three Decades of Coastal Change.” Geoscience Australia, 14 Apr. 2021, www.ga.gov.au/news/digital-earth-australia-coastlines-tool.
Dennison, Bill. “Practical Visual Literacy for Science Communication | Blog | Integration and Application Network.” Ian.umces.edu, 28 Mar. 2017, ian.umces.edu/blog/practical-visual-literacy-for-science-communication/.
Explore Beaches. “Beach Nourishment | Explore Beaches.” Explorebeaches.msi.ucsb.edu, 2022, explorebeaches.msi.ucsb.edu/beach-health/beach-nourishment.
Masterson, Victoria, et al. “Sea Level Rise: Everything You Need to Know.” World Economic Forum, 20 Sept. 2024, www.weforum.org/stories/2024/09/rising-sea-levels-global-threat/.
NASA. “Which Areas of the World Will Be Most Affected by Sea-Level Rise over the next Century, and after That?” NASA Sea Level Change Portal, 2023, sealevel.nasa.gov/faq/17/which-areas-of-the-world-will-be-most-affected-by-sea-level-rise-over-the-next-century-and-after-that/.
National Geographic. “Beach | National Geographic Society.” Education.nationalgeographic.org, 2023, education.nationalgeographic.org/resource/beach/.
Roy, Eleanor Ainge, and Sean Gallagher. ““One Day We’ll Disappear”: Tuvalu’s Sinking Islands.” The Guardian, The Guardian, 20 June 2019, www.theguardian.com/global-development/2019/may/16/one-day-disappear-tuvalu-sinking-islands-rising-seas-climate-change.
