Residents in Msida and Birżebbuġa may have been alarmed in recent days as the sea rose above its usual levels, flooding low-lying roads.

The cause of the high waters was not climate change or tidal forces but a phenomenon referred to by experts as an “atmospheric tsunami”, technically known as seiche waves or locally as milgħuba.

The phenomenon is not uncommon and several instances of it have been recorded in coastal areas around Malta in recent years.

According to the Gozo Weather Page on Facebook, the seiche waves are caused by fluctuating atmospheric pressure that makes open sea waves rise and fall.

This is a result either of an area of high pressure out at sea or an area of low pressure at the coast causing the sea to rise. It can also be caused when the wind blows steadily from the same direction for a prolonged period of time.

The high sea level in Birżebbuġa yesterday.The high sea level in Birżebbuġa yesterday.

Due to the bay being enclosed, the water oscillates, like in a bathtub when sloshing from one side to the other, and, as a result, waves could be seen moving away and back into the bay.

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The waves are very similar to tsunami waves but are much smaller and the result of a completely different mechanism, with tsunamis the result of tectonic activity such as earthquakes.

While the phenomenon is unrelated to global sea level rises resulting from climate change, it could offer a snapshot of the challenges Malta could face in this regard in the coming decades.

Experts have warned that a rise in sea levels would affect the whole country, with coastal areas ex-posed to increased flooding and, eventually becoming submerged.

A recent environmental study in Marsaxlokk, for example, referenced projections that, within this century, the coastline was expected to expand onto the terraced agricultural slopes beyond the current waterfront.

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