Jakarta city administration’s recent raid on 80 high-rise buildings along the Indonesian capital’s main business thoroughfare, which showed that 37 buildings are not equipped with infiltration wells and are alleged to have failed to comply with regulations on the use of groundwater, is another confirmation of what experts have warned that the city is well on its way to become an underwater metropolis.
The 2017 World Ocean Review, which was published in November last year in Berlin, reports that Jakarta is currently the fastest sinking city in the world, subsiding at a rate much faster than other coastal metropolis of over 10 million inhabitants in Southeast Asia such as Bangkok, Ho Chi Minh and Manila.
According to the report, Jakarta, which is partly built on peaty soils, is an “extreme example of a sinking city” with many of its high-rise buildings and the commercial center are sinking in the soft subsurface by up to 10 centimeters annually.
The abstraction of groundwater for drinking water supply is also contributing to this effect and it is feared that the sinking will accelerate. Groundwater normally acts as a natural abutment that counterbalances the weight of built-up areas bearing down on the substrate, while another factor that contributes to Jakarta land subsidence is compaction of the ground.
“Without countermeasures and a reduction of groundwater abstraction, by the year 2025 parts of Jakarta are likely to have sunk by a further 180 centimeters,” the World Ocean Review reports.
To come up with resolutions on how coastal metropolis can adapt to the land subsidence and sea level change, scientists at Leibniz Center for Tropical Marine Research (ZMT) and University of Bremen’s Institute of Sociology in Germany are working on research projects in Jakarta, Singapore and Manila.
Chief sociologist Dr. Anna-Katharina Hornidge, who is one of the scientists behind the World Ocean Review, said they are seeking to find answers on how policies and standardized practices for living with sea level rise, which are communicated by international donors can be translated into local context and are politically legitimized.
“Our recent findings so far are that the relative sea-level change serves as a floating signifier to justify investment in infrastructure to transform the coastal areas and acculturation to living with water,” Hornidge told a group of international journalists during a visit to the institution in Oct. 2017.
The evil twin of global warming: ocean acidification
But sea level rise, which is rising by around 3 millimeters annually according to the World Ocean Review, is not the only problem faced by people living in coastal areas. Those that are driven by climate change, such as ocean warming and ocean acidification, are adding to the coastal inhabitants’ woes.
Ocean acidification or the rising acid in seawater because the ocean partly absorbs the carbon dioxide that humans pump into the atmosphere, poses another threat to ocean life and marine ecosystem, impairs life in the ocean, and compromises important ecosystem services it provides to humankind, such as fish, which serve as the primary source of protein for a billion people, mainly in developing countries, and the fisheries industry that provides jobs for millions of people, especially those living in coastal areas.
Scientists have coined the terms “the other carbon dioxide problem” or the “evil twin of global warming” for ocean acidification, which has increased by 30 percent since 1850, according to Dr. Ulf Riebesell, a marine biologist at GEOMAR Helmholtz Centre for Ocean Research in the northern German seaside town of Kiel.
Riebesell, who led more than 250 scientists from a network of 20 German research institutions to conduct an eight-year research on ocean acidification called Biological Impacts of Ocean Acidification (BIOACID), said the changes in seawater acid is happening 10 times faster than it would have been if it was happening due to natural process.
Findings of the research, which was conducted from 2009 to 2017, were presented at last year’s United Nations climate change conference COP23 in Bonn. Some of the findings show that many organism are able to withstand ocean acidification but may lose the ability if also exposed to other stressors such as warming, loss of oxygen or pollution. Ocean acidification and warming reduce the survival rates of some fish species’ early life stages, which will likely reduce fish stocks and yields. Climate change also alters the availability of prey for fish and as a consequence may affect their growth and reproduction.
Scientists involved in BIOACID research found that ocean acidification reduces the ocean’s ability to store carbon and will change the distribution and abundance of fish species. The change will have a significant impact on economic activities such as small-scale coastal fisheries and tourism. This calls for therefore, the scientists said it is crucial to consider ocean acidification and warming in fish stocks and marine areas management.
Hans-Otto Portner, co-coordinator of BIOACID and marine ecophysiologist at Alfred Wegener Institute (AWI), Helmholtz Center for Polar and Marine Research said for scientists to be able to project the steady level of ocean acidification based on historical events would depend on political decisions.
“The oceans are warming, just like the rest of the planet. They are losing oxygen and acidifying. The overarching trend is marine life now is being depleted,” he added.
Riebesell said the global community needs to understand the many ways in which humans depend on the ocean and its services and it will be for humans’ own benefit if carbon dioxide emissions are reduced that it could limit global warming to less than 2 degree Celsius.
“The future of this planet depends on us. Wouldn’t it be a great achievement if the age of human dominance on earth goes down in history as an era of rethinking and changing behavior?” Riebesell added.
Portner said all countries need to reduce their carbon dioxide emissions drastically by the middle of the century if they want to meet the Paris climate targets.
“The current world climate report indicates that net-zero emissions are a precondition for limiting global warming to well below 2 degrees Celsius. However, reducing carbon dioxide emissions alone may not be sufficient,” Portner said.
Coral reef restoration
Keeping global warming further down to below 1.2 degrees Celsius with limited concentrations of carbon dioxide emissions could help to preserve about half of the tropical coral reefs, the BIOACID research found, adding more attestation on how ocean acidification will impact humans.
“Coral reefs provide habitat for millions of species, coastal protection, revenues from tourism and biodiversity heritage for the future,” Riebesell said.
According to Marine Policy journal published in August 2017, coral reefs around the world is one of the most notable examples of nature-based tourism spurred by a single ecosystem, which attract tourists and generate revenues in 100 countries and territories, including Indonesia.
Coral reef tourism is estimated to generate roughly US$35.8 billion dollars globally every year or over 9 percent of all coastal tourism value in coral reef countries around the world. Indonesia ranked second among the 10 jurisdictions in the world that have the highest total reef tourism value, amounted to US$3,098 million annually, while neighboring Thailand and the Philippines ranked fourth and seventh, generating US$2,410 million and US$1,385 million per year respectively.
Dr. Sonia Bejarano, head of the reef systems workgroup at Leibniz Centre for Tropical Marine Research (ZMT) in Bremen, said coral reefs are biodiversity treasure in need of science for sustainability.
Bejarano and a group of scientists at ZMT has been conducting research projects on coral reefs in various parts of the world, including in Indonesia, where they found that a receding destructive fishing practice in an Indonesian marine park has led to a rise in herbivorous fish.
“There is a high social and economic dependence on coral reefs,” Bejarano said, adding that their research is directly applicable in coral reef restoration.