The rise in sea level in Metro Manila’s coastlines is much higher than the global average.
The National Mapping and Resource Information Authority (NAMRIA) revealed this in a coastal engineering summit held recently in Batac, Ilocos Norte.
Based on NAMRIA’s findings, sea level in Metro Manila has risen by an average of 8.4 millimeters a year from 1901 until 2022, almost three times the global average of 3.4 mm/year in the same period.
Namria attributed this in part to the “coupling effect” of sea level rise and land subsidence — the gradual sinking of the earth’s surface.
Even the National Aeronautics and Space Administration (NASA) has attributed the rise in sea level around the world to the warming atmosphere and ocean, causing ice sheets and mountain glaciers to melt; and land water storage — through groundwater extraction and dam building.
In Metro Manila, for instance, more groundwater extractions are done through deepwells, and more buildings rise as it becomes more populated. These factors contribute to land subsidence because of the extracted water and sheer weight of the buildings and the population.
NAMRIA also cited land reclamation and deforestation as contributing factors to the rise in sea level.
The revelation on the rising sea level should be a cause for concern considering the 22 reclamation projects in Manila Bay and the perennial flooding in Metro Manila and in the neighboring provinces of Cavite, Laguna, Rizal, and Bulacan as well as Pampanga farther north.
President Marcos has already suspended the 22 reclamation projects to give way to a cumulative impact assessment that will be conducted by the Department of Environment and Natural Resources (DENR). The agency, headed by Secretary Maria Antonia Yulo-Loyzaga, should look closely and deeper into the overall effects of these reclamation projects.
The DENR should also keep in mind the continuing mandamus issued by the Supreme Court in 2008, which directs it and 12 other government agencies “to clean up, rehabilitate, and preserve Manila Bay, and restore and maintain its waters to SB level.” The mandamus issued by the highest court of the land is clear — there is no room for misinterpretation.
And with the rising sea level now a global phenomenon, the DENR needs to look closely on how these reclamation projects will impact low-lying areas. As of now, these areas are already vulnerable to flooding.
Through dump-and-fill, these reclamation projects in Manila Bay are certain to contribute to the rising sea level — that is the Archimedes principle in which any body completely or partially submerged in a fluid is acted upon by an upward force, or what is called a buoyant force. Under this principle, there is no other way for water in Manila Bay to go, but up with these reclamation projects.
If sea level in Manila Bay rises, this will pose a threat to coastal and inland communities which are already vulnerable to flooding.
How to mitigate this is a responsibility not solely in the hands of the government, but all responsible citizens of the country.
We hope everyone will contribute his or her own share in keeping the rise in sea level to a bare minimum. Let’s help keep our environment safe.