Letter: Clarifying ‘sea level rise’
In his Nov. 17 article "Study addresses concerns about saltwater intrusion in region," Bill Nachman presents his "cherry picked" portions of a four-page report from the Virginia Institute of Marine Science. His readers would benefit from knowing that not all "sea level rise" is the same.
There is global sea level rise, and is measured by tidal gauges and more recently by satellites. The numerical values depend where, and over what period of time the measurements are taken. Portions of the oceans can be rising as other portions are falling. The most recent data quoted are for a global average rise of about seven inches over the past 100 years, and a deceleration in the rate of rise.
Local sea level rise is the relative rise measured in a particular region, once such factors as land mass rebound and subsidence are factored in. Chesapeake Bay is an active geological region reflecting the original meteor impact and ice coverage and retreat when the last ice age resolved. The ongoing geological activity there makes it imperative that the simplistic term "sea level rise" be better qualified.
The article makes reference to "various sea level scenarios." The term scenario is the code word for computer model results. Thus the reader should understand that the results depend upon the validity of the model to predict accurately changes out to the year 2100. The computer model will take in whatever number you wish and crank out what your program constrains it to do. The unqualified "sea level rise" input ranged from the historic norm of about half a foot to an arbitrary five feet. Why not ten feet, 20 feet? Pick the number you want to give the most frightening story?
The computer exercise gave a 30 to 1 ratio of bay salinity; how meaningful is this? The report uses "can," "if," and "might." A meteor might strike the Earth; it could happen; if it happened it would be "problematic."
The bay area has real problems; it does not help to muddy the waters further.
Charles Battig, M.D.
President, Piedmont Chapter
Virginia Scientists and Engineers for Energy and Environment