NOAA predicts that the 2012 hurricane season, which began June 1 and lasts for six months, will be of average activity, consisting of about 12 named storms, with six of those developing into hurricanes.
The seasonal outlook does not predict how many of these storms will actually make landfall, or where they will hit.
But if and when they strike the Virginia coast and move up the Chesapeake Bay and its tributary rivers, low-lying areas near the water's edge will experience costly, devastating floods, as they have for hundreds of years.
Virginia sea level rising
Depending on a storm's timing, it may hit when coastal water is already at high tide, pushing the storm surge, generated by the storm's high winds and low atmospheric pressure, far above normal sea level. This makes sea level an important factor in how much damage a storm will cause.
Tide gauges along the Atlantic Coast and the Chesapeake Bay, including one at Sewell's Point in Norfolk, Va., have recorded the relative sea level for decades. These gauges all show a gradual sea level rise from the beginning of the data until now.
For example, during the years between during the deadly Hurricane of 1933 and Hurricane Isabel (2003), the relative sea level in the lower Chesapeake Bay rose 1.35 feet.
Global warming accelerating sea level rise?
Some climate scientists blame global warming for the sea level rise along the Virginia coast, and they believe the rise will accelerate as the world warms, increasing the flooding and destruction caused by seasonal hurricanes.
Climate modelers have predicted sea level rises for the East Coast from 1-1/2 feet to 8 feet or more by the year 2100, due to global warming. One study said that Washington, D.C., on the Potomac River upstream from the Chesapeake Bay, might be inundated by a 21-foot rise in sea level, if the Antarctic Ice Shelf collapses.
More recent research from the Virginia Institute of Marine Science (VIMS) has shown that these drastic seal level changes are not very likely, and that more probably, the rise would be around 1/4 inch per year:
“From the evidence these stations provide, local rise rates are expected to be nearly twice the global rate, or about 4 mm per year, and may prove to be as high as 5 to 7 mm per year. This equates to up to one foot (0.3 m) of sea level rise, relative to the land, by 2050.” (VIMS, Planning for Sea Level Rise and Coastal Flooding, 2008)
Virginia is slowly sinking
In fact, scientists at VIMS believe that at least part of the relative sea level rise is due to the mid-Atlantic region slowly sinking. This subsidence might be caused by:
- Melting polar ice caps following the last Ice Age, causing land under the ice to bounce back up when the weight is released, moving it down in other areas.
- Shifting subterranean faults associated with the Chesapeake Bay Impact Crater, located almost directly in the middle of the Bay.
- Local groundwater withdrawals for use by a growing population.
Of these causes, only the last can be controlled by changes in human activity. And according to VIMS, this subsidence isn't likely to change significantly.