Global sea levels continue to rise as the world warms and the ice caps melt, and Singapore is not spared from this.
According to the annual climate assessment report 2019 released by the Meteorological Service Singapore (MSS) on Monday (23 March), the average sea level around the island now is 14cm higher than the pre-1970 levels.
As water expands when heated, which causes sea level to rise and thus “warming oceans cause sea level to rise… Similarly, melting of glaciers, Greenland and Antarctica ice sheets ultimately reach the ocean, thus further increasing sea level,” the MSS report stated.
Based on data from tide gauges included in the MSS report, global sea level has been increasing at a pace of 1.2mm to 1.9mm each year in the 20th century.
Benjamin Horton, a sea level rise expert from the Nanyang Technological University, stated that the primary driver of sea level rise in the 20th century is the thermal expansion of water.
However, situation in the 21st century has been deteriorating due to the increasing rates of ice melting from the world’s ice sheets.
MSS reported that since 1993, global average sea level increased at a rate of around 3.24mm annually in the period where high-precision data became available for monitoring sea level.
In 2019, sea levels reach the highest level recorded so far, which was 90mm higher than the level in 1993, MSS report highlighted.
“If all of Greenland is melted, it will contribute 6m to sea level rise,” Professor Horton remarked. He added that Antarctica faces greater impact because sea levels could increase by around 60m if the Antarctic Ice Sheet melts entirely.
Prior to this latest MSS report, the United Nations climate science body also released a report in September 2019. Similarly, the United Nations report found that sea levels may increase by several metres in the next centuries if warming continued without stopping. Sea levels could increase by around 1m by 2100, according to earlier estimates.
The impact of sea levels on coastlines is a complex field of study because sea level rise varies regionally, is not uniform and occurs at different time scales.
For instance, Singapore’s rates of sea level rise might be above the global mean, Prof Horton noted. He further elaborated that “if an ice sheet melts, its gravitational attraction decreases and sea levels around it can go down…Conversely, regions far from a melting ice sheet, such as Singapore, will see a rise in sea level greater than the global average.”
Furthermore, sea levels may vary over shorter periods. For instance, MSS report noted that sea levels can increase by up to 0.2m during the north-east monsoon, which is the region’s yearly rainy season.
Variations in sea levels can also happen due to natural climate phenomena like the El Nino events, which can take place once two to seven years. The 2015 El Nino event was the last major one that occurred.
Aside from studying how sea levels around the country were impacted by El Nino 2015, the MSS is also studying the positive phase of the Indian Ocean Dipole. The Indian Ocean Dipole is a climate event similar to El Nino which took place in 2019 in the Indian Ocean.
MSS spokesman, who remarked that more details will be made available later, also noted that “this is currently being studied and will be part of a soon-to-be published journal paper.”
As a low-lying country with around 30 per cent of the island less than 5m above the mean sea level, Singapore is very much aware of its vulnerability to rising sea level and so it is actively curbing the impact.
Prime Minister Lee Hsien Loong pointed out in August 2019 that S$100 billion in spending is required in the long term to protect Singapore’s coast from the rising tides. According to the Deputy Prime Minister Heng Swee Keat in February, the initial investment of S$5 billion will be provided to the country’s new coastal and flood protection fund.
Also, research in this scientific field is progressing. “The National Sea Level Programme will use this information to better understand the sea level variability. This is crucial in order to better assess future projections of sea level rise, since the long-term trends are superimposed onto this variability,” MSS spokesman concluded.
