BONN, Germany —
Along the coast, the country has been spouting huge amounts of sand in strategic locations offshore and allowing the natural motion of waves to strengthen defensive dunes.
VENICE, Italy. Sea level rise is a particular concern for this flood-prone city. It’s in the process of realizing an expensive and oft-delayed system of underwater barriers that would be raised in the event of flooding over 43 inches (110 centimeters), higher than the 31-inch (80-centimeter) level that floods the famed St. Mark’s Square.
Venice, a system of islands built into a shallow lagoon, is extremely vulnerable to rising seas because the sea floor is also sinking.
The constant flooding puts the city’s considerable architectural treasures at risk. Venice has experienced 10 events over 4 feet 7 inches (140 centimeters) since 1950, including a devastating 1966 flood. Plans for the new so-called Moses barriers will cost more than 4 billion euros. The first of these have been moved into place in recent days. Many Venetians remain skeptical of the project due to the high costs and concerns over environmental risks.
LONDON. The low-lying capital of a perpetually soggy country, London has long been vulnerable to flooding — particularly when powerful storms send seawater racing up the River Thames.
But Londoners already have a powerful flood defense: the 570-yard-long (half-a-kilometer-long) Thames Barrier, composed of 10 massive steel gates, each five stories high when raised against high water.
Some have called for Thames Barrier — in operation since 1982 — to be replaced or supplemented by an even more ambitious flood defense system farther down the river. But Britain’s Environment Agency says the defenses should hold until 2070.
Meanwhile, environmentally conscious Londoners have made plans to battle some of the other predicted effects of global warming by promoting better water management, expanding the city’s Victorian sewage network, and “urban greening” — the planting of trees and rooftop gardens to help manage the urban heat island effect.