Oceans attack: Global flood risks in the 21st century

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Planet Earth should have been named planet Water. This popular joke among geographers contains more than a grain of truth: the world ocean covers two-thirds of the surface of our planet.

Planet Earth should have been named planet Water. This popular joke among geographers contains more than a grain of truth: the world ocean covers two-thirds of the surface of our planet. Its increasingly erratic behavior is one of the topics being discussed at the UN Climate Change Conference in Cancun (Mexico), which will run from November 29 through December 10. The question at the heart of the discussion sounds like an idea for a disaster film: what cities will be flooded first if the world ocean rises one meter by the end of the 21st century?

The threat of flooding will be the greatest in St. Petersburg, the Yamal Peninsula, Northern Germany, the Netherlands and the deltas of the Nile and Ganges, as well as in the world's other lowlands, predicts Sergei Dobrolyubov, head of the oceanography chair at the department of geography at Moscow State University. If sea level rises a meter and a half, nearly all of Bangladesh will be flooded, affecting 17 million people according to estimates. Florida and the Maldives are also considered high-risk zones.

A "growing" ocean

According to satellite data and coastal measurements, sea level is rising by 2 to 3 mm per year. There are two reasons for this.

First, continental glaciers are melting. According to Alexander Kislov, head of the meteorology and climatology chair at the department of geography at Moscow State University, mountain ice caps are retreating all over the planet. For example, Mount Kilimanjaro, the highest mountain in Africa (5895 meters), recently lost its ice cap.

Second, the water in the ocean is expanding due to global warming. We all know from physics classes that heat causes a body to expand.

A one-meter rise in the world ocean by the end of the 21st century may not seem significant at first glance, especially considering that the Caspian Sea has risen by 2.5 meters since 1997. But the change in the Caspian is a local factor.

A rising world ocean, on the other hand, is a global issue affecting many countries.

Killer waves

Over the past 60 years, oceanographers say that storm waves (or "killer waves") have been getting higher and, consequently, more devastating, especially in the northern Atlantic and northern Pacific. In the past decade alone, tidal waves have grown by 10 to 12 cm. The highest storm wave registered so far was 34 meters. But even a 20-meter killer wave can be extremely dangerous to ships and oilrigs.

The deadliest natural hazards involving the atmosphere and the ocean are tsunamis, typhoons and storm surges.

A 10-meter tsunami is much more dangerous than a 20-meter storm. Tsunamis are longer and move faster. Storm waves hit the coast at separate spots, whereas tsunamis strike the coast as a continuous kilometers-long wall of water. That powerful mass of water can kill people and crush coastal buildings and ships.

In 2004, a tsunami in the Indian Ocean claimed the lives of over 270,000 people. Leading oceanographers are drawing bleak parallels recalling other tsunamis that washed away entire civilizations. A tsunami triggered by a volcanic eruption on the Santorini Island is thought to have destroyed the Minoan civilization.

To understand the destructive force of a tropical cyclone, look no further than Hurricane Katrina, which descended on New Orleans in the autumn of 2005. Storm surges in deltas can be equally catastrophic. For example, the surge caused by the 1970 Bhola cyclone killed 300,000 people in Bangladesh.

But storms are becoming more frequent even in the Arctic Ocean as the area that is free of ice continues to increase. According to oceanographers, coastal ice in that region is retreating by 10 to 15 cm per year.

"And soon the islands flooded lay..."

St. Petersburg, which has survived 305 incidents involving rises in water level since its founding, is the most waterlogged city in Europe alongside Venice. Alexander Pushkin described St. Petersburg's worst flood of 1824 in his poem the Bronze Horseman: "...But the wind driving from the bay/ Dammed Neva back, and she receding/ Came up, in wrath and riot speeding/ And soon the islands flooded lay..."

According to Alexander Rybalko, chief researcher at the Sevmorgeo center for maritime geological exploration, even minor floods, when the water level rises by 1.5m or more, erode foundations and flood basements. Nature is on the offensive, and Rybalko believes the city needs facilities that will protect it from even the slightest changes in water level.

Valery Malinin, professor at the Russian State Hydrometeorological University, warns that the St. Petersburg Flood Prevention Complex can itself trigger a storm surge flooding vast areas of St. Petersburg and its suburbs.

This system of dams, which has been under construction since 1979, runs along the Gulf of Finland from Bronka to Sestroretsk through Kotlin Island, where Kronstadt stands. If a storm surge higher than 6 meters occurs "it would not be possible to express the damage in monetary terms," the professor says.

The revenge of Mother Nature

Oceanographers continue their costly and complicated research using 4,000 solar-powered buoys in the world ocean, satellites and research vessels such as Academician Joffe, Mstislav Keldysh and Academician Sergey Vavilov. And while predictions are not hard facts, continuous monitoring of the world ocean has led researchers to conclude that it is all but impossible to slow the rise of the sea level.

The ocean's climate system is inertial. Massive carbon dioxide emissions continue to heat up the atmosphere (the average temperature on Earth has risen by 0.76 degree Celsius over the past century). And as temperatures increase, so too will the volume of the water in the ocean and the sea level.

Researchers are unanimous in their conclusion: it's time for humanity to start adapting to the new realities and build structures to protect itself from the ocean's next attack.

The views expressed in this article are the author's and do not necessarily represent those of RIA Novosti.

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