What is sea level and why is it rising?
Sea level (or ocean level) is a measurement of the height of the ocean surface. Sea level has globally risen by approximately 20 cm since 1901, threatening many coastal regions around the world with inundation. Morocco will likely not be spared.
Climate change causes an increase in average sea level for two main reasons: the melting of land ice and thermal expansion.
The melting of land ice is the most intuitive. Rising temperatures cause glaciers and polar ice sheets to melt. The melted ice enters the ocean and contributes to rising sea level. This effect must be distinguished from the melting of sea ice, which is already in the water, and therefore does not contribute to rising sea level, contrary to what one might think.
Moreover, rising temperatures cause the oceans to warm. However, at a higher temperature, the same amount of water occupies more volume. This effect, called thermal expansion, is also a significant contribution to rising ocean levels. It is responsible for approximately one-third of the current sea level rise.
Projections for 2100 in Morocco
In the latest IPCC report, it is projected that by 2100, global sea level would increase by 0.34m for 1.5°C of warming and by 0.81m for 3°C of warming. For reference, we are currently headed toward 2.7°C of warming.
For a rise of 0.44m, it is projected that in Morocco 1.82 million people would be affected. For a rise of 0.39m, it is projected that approximately half of the beaches between Saidia and Ras el Ma would be eroded. For a rise of 0.89m, virtually all of Tangier's beaches would disappear, as would more than three-quarters of the tourism infrastructure in the area.
Consequences of rising sea level in Morocco for different elevation levels by 2100
Coastal infrastructure (ports, warehouses, shops) and waterfront homes are directly threatened by rising water levels. If no adaptation measures are undertaken, the estimated average cost of damage is 191 million dollars in 2050 for Casablanca alone!
In Morocco, more than 60% of the population and more than 90% of businesses are located in major coastal cities. These cities — such as Casablanca, El Jadida, and Agadir — and their populations are therefore directly exposed to rising sea level. The chart below shows the shares of the population that would be below water level in 2100 and in the long term for warming of 1.5°C and 3°C.
By 2100, less than 4% of the populations of the main urban agglomerations are directly threatened by rising sea levels, with little difference between 1.5°C and 3°C of warming. This figure drops below 1% for Agadir, Rabat, Safi, and Tangier.
Since ocean dynamics are very slow, sea level rise will continue long after 2100. In the long term, the difference in population exposure based on warming levels is more marked. In particular, we note that for 3°C of warming (we are currently headed toward 2.7°C), the city of Dakhla is destined to completely disappear.
Share of the population of different urban agglomerations that will be below sea level for global warming of 1.5°C and 3°C (2010 population used as reference). Source: u003ca href=u0022https://iopscience.iop.org/article/10.1088/1748-9326/ac2e6bu0022u003eStraus et al. 2021 u003c/au003e
Visualization of Submerged Lands
Using the online tool Climate Central, it is possible to visualize submerged lands in 2100 for different warming levels.
For example, you can compare below in red the lands that will be submerged in 2100 for warming of 1.5°C and 3°C around Kenitra and Tétouan.
You can observe that Essaouira is particularly threatened by a rise in water levels that would submerge all lands facing the ocean and a large part of the city.
What is sea level and why is it rising?
Sea level (or ocean level) is a measurement of the height of the ocean surface. Sea level has globally risen by approximately 20 cm since 1901, threatening many coastal regions around the world with inundation. Morocco will likely not be spared.
Climate change causes an increase in average sea level for two main reasons: the melting of land ice and thermal expansion.
The melting of land ice is the most intuitive. Rising temperatures cause glaciers and polar ice sheets to melt. The melted ice enters the ocean and contributes to rising sea level. This effect must be distinguished from the melting of sea ice, which is already in the water, and therefore does not contribute to rising sea level, contrary to what one might think.
Moreover, rising temperatures cause the oceans to warm. However, at a higher temperature, the same amount of water occupies more volume. This effect, called thermal expansion, is also a significant contribution to rising ocean levels. It is responsible for approximately one-third of the current sea level rise.
Projections for 2100 in Morocco
In the latest IPCC report, it is projected that by 2100, global sea level would increase by 0.34m for 1.5°C of warming and by 0.81m for 3°C of warming. For reference, we are currently headed toward 2.7°C of warming.
For a rise of 0.44m, it is projected that in Morocco 1.82 million people would be affected. For a rise of 0.39m, it is projected that approximately half of the beaches between Saidia and Ras el Ma would be eroded. For a rise of 0.89m, virtually all of Tangier's beaches would disappear, as would more than three-quarters of the tourism infrastructure in the area.
Coastal infrastructure (ports, warehouses, shops) and waterfront homes are directly threatened by rising water levels. If no adaptation measures are undertaken, the estimated average cost of damage is 191 million dollars in 2050 for Casablanca alone!
In Morocco, more than 60% of the population and more than 90% of businesses are located in major coastal cities. These cities — such as Casablanca, El Jadida, and Agadir — and their populations are therefore directly exposed to rising sea level. The chart below shows the shares of the population that would be below water level in 2100 and in the long term for warming of 1.5°C and 3°C.
By 2100, less than 4% of the populations of the main urban agglomerations are directly threatened by rising sea levels, with little difference between 1.5°C and 3°C of warming. This figure drops below 1% for Agadir, Rabat, Safi, and Tangier.
Since ocean dynamics are very slow, sea level rise will continue long after 2100. In the long term, the difference in population exposure based on warming levels is more marked. In particular, we note that for 3°C of warming (we are currently headed toward 2.7°C), the city of Dakhla is destined to completely disappear.
Visualization of Submerged Lands
Using the online tool Climate Central, it is possible to visualize submerged lands in 2100 for different warming levels.
For example, you can compare below in red the lands that will be submerged in 2100 for warming of 1.5°C and 3°C around Kenitra and Tétouan.
You can observe that Essaouira is particularly threatened by a rise in water levels that would submerge all lands facing the ocean and a large part of the city.
Go to Climate Central to explore Morocco's coasts of 2100 yourself.