Human-induced sea level rise portends more typhoon risks

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  • Study shows a global average rise in sea level of 1 centimetre a year
  • Philippines and Australia have the highest annual sea level rise at 3 centimetres
  • Storms moving over higher seas increase the threats of storm surge and flooding

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[MANILA] Countries in the Pacific should brace for increased risks from typhoons after a research study shows that human-induced sea level rise trends higher in the Pacific Ocean than in any other parts of the world.
“The impact of typhoons on coastal populations will be much greater if sea levels continue to rise. Storms moving over higher seas increase the threat from storm surge and the possibility of significant coastal flooding,” says Ben Hamlington, assistant professor at the Department of Ocean, Earth and Atmospheric Sciences at Old Dominion University, a public research institute in Virginia, United States, and lead author of the research published in Nature Climate Change (20 July).
In particular, the coasts of Australia and the Philippines are said to have the highest annual sea level rise at three centimetres (cm) — compared with the global average of one cm a year — based on satellite altimetry that measures the altitude of an object above a fixed level. Worldwide, for the past two decades, sea level rose 20 cm (8 inches).
The scientists arrived at the conclusion that human activities are causing sea level rise in the Asia-Pacific region, by estimating and removing the Pacific Decadal Oscillation (PDO) in the equation.
The PDO, a temperature pattern similar to the El Niño phenomenon, can significantly contribute to regional and global sea levels trends as the event lasts for up to 30 years. In effect, the PDO tends to “hide or mask” underlying human-induced climate change and sea level rise impact, Hamlington tells SciDev.Net.
Their research, according to Hamlington, highlights a strong need to integrate climate adaptation with disaster mitigation, especially as the world prepares for 2015 climate talks in Paris and the post-2015 sustainable development agenda.
“Finding strategies to curb sea level rise in the short term is difficult. Many countries are already experiencing the impacts and effects of sea level rise, and these areas must take steps to adapt and mitigate,” says Hamlington.
In November 2013, the Philippines was hit by super typhoon Haiyan, which brought record storm surges of 5-7 metres in height. Changes in climate patterns and currents in the Pacific — where most typhoons form — can cause more severe weather events that occur once in 50 to 100 years.
“For some, the future predicted by models is happening now,” adds Koko Warner, author of a policy brief on human mobility and climate change published by the UN University Institute for Environment and Human Security and the Nansen Initiative.
Warner warns that coastal erosion is one of the effects of sea level rise that would directly impact communities living along shorelines, leading to loss of habitat and local sources of livelihood.
Sea level rise will also increase the pressures of migration and forced displacement of populations in vulnerable areas. Migration should thus be woven into national adaptation plans using evidence-based assessment, reiterates Warner.

Sea level rise can also impact culture and heritage as seen in Micronesia, which had to destroy centuries-old ports to build sea walls to protect communities from big waves, notes Warner.

The Fifth Assessment of the UN Intergovernmental Panel on Climate Change said it best, says Warner: ”’The decisions we made today have multi-century implications.’ We can’t go back to the normal as we used to know it.”

Link to abstract in Nature Climate Change

This article has been produced by SciDev.Net's South-East Asia & Pacific desk


Nature Climate Change doi:10.1038/nclimate2307 (2014)