Manila Bay’s tides are increasing, scientists warn

A new study reveals that Manila Bay's tides have changed significantly since monitoring started in the 1980s, with an over 1 mm increase per year in average high water and over 5 mm per year in greater diurnal tidal range (GDTR).

This may not seem like much, but it will influence life along the coastline through factors such as access to ports, where buildings can be constructed, and distribution of species.  

 

Manila Bay is just one of the many sites around the world included in the study where tides have changed. The study was conducted by researchers from the University of Southampton and published in the journal Earth's Future.

Global concern
 

Tides were previously considered to be relatively constant over time and were not expected to change over the next 100 years as the astronomical forces that generate them are virtually constant. However, analysis of sea level data from 220 tide gauge sites around the world, with some data spanning over 100 years, showed that changes in tides are occurring worldwide. Some sites have tidal changes comparable to changes in mean sea level (MSL) due to sea level rise. But while the changes are global, the researchers did not find a global pattern.

 

“The magnitude and global distribution of changes in tides have been hinted at before,” said study co-author Ivan Haigh. “However, here we have been able to assess changes in different tidal levels, which are used for many practical applications. Tides exert a major influence on the coast, affecting coastal flooding and erosion, navigation, tidal energy extraction, sediment movement and the extent of species in coastal ecosystems. Therefore, the changes we have identified have wider ranging practical and scientific implications, particularly if they increase in the future.”

Climate change

 

Says co-author Neil Wells, “The cause of these changes is complex and appears to be a combination of mechanisms from local to global, with the primary driver being the rise in sea level associated with climate change. Further research is required to more fully understand the mechanisms causing these changes and to understand how tides might further change in the future.” — TJD, GMA News

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Macy Añonuevo earned her MS Marine Science degree from the University of the Philippines. She is a published science and travel writer and was a finalist in the 2013 World Responsible Tourism Awards under the Best Photography for Responsible Tourism category. Her writings and photographs may be found at www.theislandergirl.com.