Japan’s new sea defences could be “overwhelmed” by future tsunamis as sea levels rise, warn researchers

  • Japanese government should consider rising sea levels when constructing new sea walls after devastating tsunami in 2011
  • Extreme tsunamis expected to become more frequent as global heating melts polar regions
  • University of Sheffield findings have implications for coastal and low-lying regions at risk of destructive tsunami worldwide

Taro, north east Japan

The Japanese government’s “failure to imagine the future” means brand new sea defences could be overwhelmed in the face of extreme tsunamis made more destructive by rising sea levels, according to academics at the University of Sheffield.

Experts at the University’s School of East Asian Studies found that the Japanese government did not account for global heating-driven sea level rises in its recommendations after the devastating earthquake and tsunami of 11 March 2011.

In a paper published in The Asia-Pacific Journal, the academics studied the seawall under construction in Tarō, north east Japan – where sea defences were destroyed by the 2011 tsunami. They found that, while the new wall represents an “incremental improvement on pre-2011 defences”, it risks being overwhelmed by a future tsunami of a similar scale.

The findings have implications for coastal and low-lying regions around the world that are at risk of destructive tsunami, as recent research shows arctic permafrost is already melting at levels not expected until 2090. The University of Sheffield experts showed that the resulting rise in sea levels could make tsunamis on the scale of 2011 more common.

The academics likened the Japanese government’s post-2011 recommendations to France’s catastrophic mistake in constructing the Maginot line in the 1930s. The fortifications were built to defend against the type of assault Germany carried out in 1914, but resulted in the encirclement and near annihilation of the allied forces at Dunkirk, and effectively allowed France’s defeat and occupation. Instead of looking to the past when planning for future disasters, they are calling on Japan to “imagine the future”.

Dr Peter Matanle, Senior Lecturer and Director of Research and Innovation at the University of Sheffield’s School of East Asian Studies, said: “By failing to include the consequences of climate breakdown in its disaster prevention strategy, the Japanese government may be putting future communities at elevated risk of a devastating tsunami.

“Sea levels are likely rising faster than scientists’ earlier predictions – and our research shows that the government should consider including sea level rise as an additional risk factor in tsunami disaster risk reduction planning.

“Instead of preparing for the past by failing to imagine the future, governments around the world must live up to their obligations in the Paris climate agreement and adopt a transformational approach suitable for an era of increasingly severe ‘mega disasters’.”

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