ASTORIA - As the Earth warms, scientists predict that polar ice caps and glaciers will continue to melt, raising the sea level around the world.
Although the amount may vary from place to place, an intergovernmental panel of scientists has predicted that by 2100, sea level will rise by between four and 35 inches.
If the maximum holds true, by 2100 the Astoria neighborhood of Alderbrook and other low-lying areas in Clatsop County might not be the best place to be.
Normal weather doesn't pose a problem, said Astoria Public Works Director Ken Cook. But high tides during the winter, when the rivers are high and winds from a storm hold the tide up, could cause damage,.
Any substantial rise in sea level would mean that the city would have to examine how to protect the low-lying areas of Astoria, with options such as dikes and tide gates, Cook said. "It would be an engineering challenge, if you had to raise the waterfront three feet higher. There would be a lot of changes necessary."
Where's the beach?Warrenton, with the ocean on one side and the river on another, would be affected by a rise in sea level as well, said its city manager, Ed Madere. The shore would probably experience more erosion, and there would be "certainly less of a beach," he said.
On the river side, a 3-foot rise in sea level would mean that the dikes along the Columbia and Skipanon rivers would need attention.
"The thing that comes first to mind would be the need to improve the dike structure on the river side," Madere said. The dikes are sufficient with the high tides now, he said but could need to be raised to hold back a few extra feet of water. While the beach areas are at sea level, most of the city of Warrenton is around 30 feet.
Fear of erosion in Cannon BeachIn Cannon Beach, "the most immediate effect would be a lot more coastal erosion hazards," said Rainmar Bartl, Cannon Beach's city planner, though he added that it is difficult to say what exactly would happen.
"The ocean-front houses could have a lot more risk of the land between themselves and the ocean eroded away."
The downtown area is protected by old seawalls and a dike along Ecola Creek that Bartl said was "not very high. If sea level keeps going up, it would take less and less of a severe storm to basically come either across the seawalls or, more likely, run up the creek and overtop the dike."
Strengthening the dike would be a significant and costly undertaking, however, and he doesn't know where the money to do so would come from.
"There's so much demand on people's resources now for immediate needs."