Of the 25 cities most exposed to a 1-meter sea-level rise, about 19 of them are located in the Asia and Pacific region, according to a study co-produced by the Manila-based Asian Development Bank (ADB).
Curiously enough, seven of the 19 cities in the region are found in the Philippines. Four are from Luzon (Manila, Taguig, Caloocan and Malabon), two from Mindanao (Davao and Butuan) and only one from the Visayas (Iloilo).
“Under a business-as-usual scenario, a 6-degree Celsius temperature increase is projected over the Asian landmass by the end of the century,” said the study’s report, “A Region at Risk: The Human Dimensions of Climate Change in Asia and the Pacific,” which Potsdam Institute of Climate Impact Research co-produced.
“Coastal regions of Asia and the Pacific are among the most vulnerable to climate change-related SLR (sea-level-rise),” the report pointed out, adding that global flood losses are expected to increase to US$52 billion per year by 2050 from US$6 billion in 2005.
It must be recalled that a previous study published in Nature said that the world’s oceans are now rising far faster than they did in the past. The current sea-level rise rate – which started in 1990 – is 2.5 times faster than it was from 1900 to 1990.
The study found that for much of the 20th century, sea level rise was about 30% less than earlier research had figured. “But that’s not good news because about 25 years ago the seas started rising faster and the acceleration in 1990 turns out to be more dramatic than previously calculated,” wrote Seth Borenstein in a dispatch for Associated Press.
“We’re seeing a significant acceleration in the past few decades,” study lead author Carling Hay, a geophysical researcher at Harvard University, was quoted as saying.
According to the report written by Borenstein, previous research showed that between 1900 and 1990, the seas rose about two-thirds of an inch a decade. The new study recalculates the 1900-1990 rate to less than half an inch a decade. Old and new research both say that since 1990s seas are rising at about 30 millimeters a decade.
“The implications are troubling – accelerated ocean warming, ice sheet collapse and sea level rise – all point to more and more sea level rise in the future, perhaps at a faster rate than previously thought,” noted Jonathan Overpeck, co-director of the Institute of the Environment at the University of Arizona. “This will make adaptation to climate change more difficult and costly.”
As a consequence of climate change, project sea-level rise is a highly difficult, complex, and controversial scientific problem, according to a report released by the Washington, D.C.-based World Bank.
Using the analysis of “semi-empirical” approach – projecting global sea-level rise by taking into account the observed relationship between past sea-level rise and global mean temperature over the past millennium – a 50 centimeter sea-level rise by the 2050s “may be locked in whatever action is taken now.”
The World Bank report – entitled Turn Down the Heat: Climate Extremes, Regional Impacts and the Case for Resilience – maintained: “Limiting warming to 2⁰C may limit sea-level rise to about 70 centimeters by 2100, but in a 4⁰C world over 100 centimeters can be expected, with sea-level rise in the tropics 10-15% higher than the global average.”
A research conducted by the Philippine Country Study to Address Climate Change, the Manila Bay is already subjected to several hazards, including flooding and storms. “Shoreline changes due to reclamation for housing, ports, coastal roads, buildings and other urbanized development are high, adding to an increased threat of inundation,” the study said.
Let’s take Davao City as a case in point. The recent Business Risk Assessment and the Management of Climate Change Impacts, published by the World Wide Fund for Nature (WWF) and Bank of the Philippine Islands (BPI), said that sea-level rise may create problems for Davao City’s ports.
“Located along the relatively shallow channel between the city and Samal Island, these port facilities are a nerve center for Davao City’s economy, and serve a variety of ships handling both cargo and passengers,” the risk assessment said.
Is sea level rise for real? You better ask Secretary Jesus G. Dureza, the presidential adviser on the peace process. In his column, “Advocacy Mindanao” some years back, the former press secretary believes the constant flooding in the city was due to sea level rise.
“My calculation is that (the sea level) has risen by one foot over a period of 20 years,” he wrote. “Hence, rain waters and floods no longer easily flow or empty out into the sea. They are clogged in the waterways and spill out into the riverbanks.”
According to Dureza, when flood waters rush down during high tide, they get stuck, at times and worse, a “backflow” of seawater during high tide. When seawaters rise high, it flows back inland through rivers. Hence, low-lying areas or subdivisions or residential areas around or near riverbanks are in trouble.
“I know this because I personally witnessed how the sea level had gone up over the years,” he pointed out. “Our family lived for four years in our resort house by the sea in the 1990’s while we were slowly renovating our house in the GSIS area inland. Our beach house was in fact built over the water, jutting out into the sea, with stilt cement posts and under our floor was sea water rising and ebbing.”
Dureza said the highest water level during high tides left water traces on the cement posts. “I would notice because every time I woke up in the morning, I could see the water markings,” he pointed out.
Sea level rise is also expected to make groundwater becomes salty in taste. “Salinity intrusion into groundwater resources occur naturally to some extent in most coastal regions via the hydraulic connection between groundwater and seawater including through canals and drainage channels,” the World Bank report said.
A United States Agency for International Development study in 2013 projects changes in salinity intrusion under a 30-centimeter sea-level during the 2045-2069 period, “which are expected to be moderate during the wet season but significantly more severe during the dry season.”
Salt intrusion is bad news for those living in Davao City. “Davao has traditionally tapped surface water from its rivers as its main water source,” the WWF/BPI report said. “It prides itself in the relatively high quality of its drinking water. However, salt intrusion has already been reported in city districts to shore, especially in portions of the city where groundwater extraction continues. Sea level rise may aggravate this situation.”
Scientists claim that for every meter the sea level rises, some three kilometers of inland would be inundated. The sea will literally rise to flood the plains. “Are the people ready for such scenario?” someone asked.
