Climate Change and El Niño Will Make Ocean Levels Swing Like a Seesaw

A warming planet will trigger much more frequent undulations in sea levels, especially for island communities in the Pacific.

(Photo: Joe Raedle/Getty Images)

Sep 30, 2015· 1 MIN READ
Padma Nagappan is a multimedia journalist who writes about the environment, renewable energy, sustainability, agriculture, and biotechnology.

The ups and downs experienced on a seesaw may be fun for kids in the park, but it’s alarming when climate scientists start comparing our ocean levels to the contraption.

But that’s exactly what oceanographers are predicting will happen as our planet heats up and stronger El Niño events trigger an even more extreme pendulum effect in sea levels.

“This is like climate change on steroids,” said Axel Timmermann, a climate researcher and oceanographer at the University of Hawaii, who along with other scientists analyzed these extreme swings in sea level.

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A typical El Niño event induces changes in wind patterns and causes changes in ocean currents, which redistribute warm water and result in sea levels dropping as warm water flows east. That leaves sea levels in the western Pacific lower than normal.

(Map: Matthew Widlansky, University of Hawaii)

With global temperatures rising, scientists expect El Niño events to become more pronounced and force sea levels to swing from one extreme to the other.

This is already happening on Pacific islands such as Guam and Samoa, which have seen coral reefs in shallow water become exposed and give off a stench as they decompose and die. This is often followed by a similar seesaw from north to south, exposing marine ecosystems in the southern hemisphere.

Guam. (Photo: Mark Lander)

“The shallow-water coral reefs used to be an amazing breeding ground for fish, and the seesaw is taking away this refuge,” said Timmermann, who has studied El Niño events for 20 years.

When La Niña follows, within a few months to a year, the water flows back from east to west and the same coastlines get flooded, reversing the pattern and endangering the vulnerable Pacific islands.

The researchers conducted computer simulations for four years and published a report that predicts these extremes will happen much more frequently 50 to 100 years from now. The changes in sea level, which range from six to 12 inches now, will escalate to 18 to 24 inches by 2100, they predict.

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In the past, extreme sea-level swings happened once every nine or 10 years in the Pacific islands, but Timmermann said what worries him most is that the incidents will happen closer to each other and will double in frequency, putting added pressure on ecosystems and islanders who will already be struggling to recover from previous weather disasters.

“These swings are going to intensify as the planet warms up, and the amplitude of the swing is going to be larger,” he said.