Ron Pulliam lists several possible consequences of climate change in his April 22 letter, “Future cleanup cancels any benefit.” I will focus on sea level rise.
From the National Oceanic and Atmospheric Administration’s Dec. 6, 2012, report Global Sea Level Rise Scenarios for the United States National Climate Assessment: “Since 1900, global mean sea level has been rising at a rate of approximately between 1.7 mm/yr and 3.2 mm/yr (Ablain et al 2009, Church and White 2011).” That’s millimeters folks: 1 mm equals 0.0393701 inch, 3 mm equals 0.11811 inch — that’s per year. The causes for this are numerous: land subsidence, winds, ocean currents, melting glaciers, warming oceans, dam building, deteriorating marsh lands, climate change, the list is endless.
The word used in the title of NOAA’s paper is “scenarios.” Now, scenarios and probabilistic projections are two different things. Scenarios are “what if” and projections are “what will” happen.
NOAA sets four possible scenarios of sea level rise: highest 2.0 meters; intermediate highest 1.2 meters; intermediate low 0.5 meter; and lowest 0.2 meter. “The Intermediate High Scenario is an average of the high end of ranges of global mean SLR reported by several studies using semi-empirical approaches.” (Their words, not mine). “The Intermediate Low Scenario (half of a meter) is the global mean SLR projection from the IPCC (U.N. International Panel on Climate Change) AR4 at the 95 percent confidence interval.”
