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Sea level rise impact on coastal areas in Indonesia

A recent study described Jakarta as one of the cities threatened by rising sea levels due to climate change. Extreme weather, intense groundwater extraction and the destruction of mangroves are among the reasons of Indonesia areas sinking.
Report from Science Direct called “Climate change impacts on Indonesia costal areas” explains how climate change could affect the region in different ways. The report says that coasts are vulnerable to not only sea level rise, but also to intensity of wind speed or increasing wave height and ocean temperature. Coastal areas are already said to be facing many problems, as the rising concentrations of carbon dioxide became more intense and have impact on marine ecosystems.

The source says: “Coastal erosion, coastal flooding, and water pollution are common problems that affect man-made infrastructure and ecosystems in coastal areas”. In the report Indonesia is described as ‘the world’s largest archipelagic state’, with more than 17,500 islands and 81,000 kilometres of coastline. Report states:

“The coastline of Indonesia is highly populated because around 220 million Indonesians reside within 100 km of the coast, and of these over 150 million people rely on marine resources for their livelihoods.”

The report adds how important coastal activities for the Indonesian economy are, such as marine transportation or fish cultivation and tourism. It’s essential to study and develop strategies for future coastal development, considering the effects climate change will have on them. The study then moves to explaining sea levels in depth, describing that greenhouse gases have an impact on the rise and that on average sea level has risen by 2.5 millimetres annually. One of the mentioned methods in the study to monitor the condition of the oceans were remote sensing technologies- satellite altimeter technology as one of the techniques. That section of the report offered visual representation of the observations noted during the past two decades, as the significant wave height was noted. From 2009-2012 the sea level rise was monitored in 4 locations including Ambon, Medan, Pemangkat and Manokwari. Sea level anomaly in Medan was 12.9 mm/year, in Pemangkat 3.53 mm/year and in Ambon 1.18 mm/year. The highest see level rise was in Manokwari being 14.1 mm/year.

The study notes importance on monitoring the variations in wave height, because of the ‘need for accurate operational wave data for applications such as vessel design, design of offshore and coastal structures or naval operations.’ The section analysed the wave height for the 20-year period from 1984-2003 and the wind climate data from Japan Meteorology Agency. The results were described in the study saying: “The validation showed good agreement both wind and waves data. Normalita et al (2014) reported that from 1984-2003, the trend of annual mean significant wave height was depending on observation location and time (season).”

The increasing trend of significant wave height was presented in table 2 of the study: North Natuna- 0.38 cm/ year; Banda Aceh- 0.52 cm/year; South Jogyakarta and North Papua- 0.75 cm/year. The variation was noticeable between 2000 and 2002 becoming much higher comparing to previous years. Moreover the warming of coastal waters was described as the process that continues to affect and cause changes in oceanic circulation patterns and is was said it is ‘very likely to continue to warm by as much as 4 to 8°F in the 21st century.

The Jakarta Post article from 29th February 2020 by Budi Sutrisno says: “Scientists at the Intergovernmental Panel on Climate Change (IPCC) stated in their report last year that the sea level was rising 3.6 millimetres per year. Based on this rate, the sea level could rise between 30 and 110 centimetres by the year 2100.” In the article it is said that Jakarta is the fourth-highest risk city globally and the researches predicted that ‘a large part of Jakarta will be submerged by 2050.’ Those statistics make Jakarta one of the fastest-sinking cities in the world, as the article mentions that ‘Jakarta subsided about 1 to 15 cm per year.’

Another example could be one of the recent videos from BBC on 26th of May, that was filmed by Anindita Pradana and edited by Kevin Kim. The video described the conditions of the village of Bedono, Central Java. It is currently under water due to rising sea levels and before was a home to over 200 families. In the footage, the sinking area shown from above was once a farming land, but as the tides came in- the coast began to shift. Dr Heri Andreas- from Bandung Institute of Technology- who was interviewed in that video said: “People talk about this as if it’s some kind of a natural process, but human action has caused it. This is not a natural disaster, but a man-made one.” In East Java few shophouses collapsed after a river nearby overflowed and the article from The Jakarta Post by Nina Loasana from 3rd of March 2020 explains more about this phenomenon:

“The incident inflicted no casualties, as the shophouses had been left vacant for months. The incident, however, caused cracks [on the ground] and land subsidence around 94 meters long and 10 meters wide at the site. The road in front of the shops also subsided around 43 meters long and 10 meters wide.”

Overall Indonesia coastal area is very vulnerable to climate change and such intense sea level rise and warmer ocean temperature are only few examples that allow to visualise what effects they can have on the region. As the study from Science Direct says: “These problems should receive serious attention from government to develop adaptation and mitigation plans for future development associated with coastal areas.”

By Julita Waleskiewicz

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