Letter: Sea level rise is indeed accelerating
A recent letter to the editor (“What is sea level rise all about?,” July 31 Readers Write) provides arguments that sea level, while continuing to rise, is not rising at the accelerating rates reported by the U.N. Intergovernmental Panel on Climate Change Assessment Report 5 and, in fact, accuses the IPCC of fraud.
To support these arguments, the author cites recent NOAA data from its Global Network Stations that purport to show a constant linear trend in sea level rise. It is stated that the “tidal station at Sewells Point has shown constant sea level rise of 0.17 inch per year for many years.” A recent paper from the Virginia Institute of Marine Science (John D. Boon, Journal of Coastal Research, November 2012) provides evidence that the rate of sea level rise is accelerating at Sewells Point as well as many other mid- and north-Atlantic tidal stations, based on NOAA tidal station data. To quote Boon’s paper, “The observational data support the claim that sea level rise is now accelerating at locations from Norfolk, Virginia to Halifax, Nova Scotia, at rates as high as 0.30 mm/y squared, rates that justify concern over this region of the U.S. East Coast.”
This result means that the rate of sea level rise increases by 0.30 millimeters (0.012 inches) per year, each and every year. There could be many reasons for this acceleration, including changes in ocean dynamics, as well as climate change. The paper also points out that this acceleration was not evident at stations south of Norfolk along the East and Gulf coasts.
The letter goes on to state that there is “no evidence that shows that melting glaciers and polar ice cause any rise.” In fact, there is too little water bound up in land glaciers to make a large difference in sea level were they all to melt, while polar ice cannot contribute to sea level rise as it melts, as it is floating ice. Arctic sea ice is also not recovering from its losses that have occurred in recent decades as implied in the letter, as data from the University of Washington Polar Science Center through July 31, 2014 shows a net loss of ice volume of 3,000 cubic kilometers per decade consistently since 1980 (Washington.edu…research sea-ice-volume-anomaly).
Finally, the author’s statements about Antarctic ice mass is not consistent with published data showing the entire Antarctic ice sheet (along with the Greenland ice sheet) to be in a state of net mass loss for over a decade with mass losses between both ice sheets of over 300 million metric tonnes per year and a net contribution to sea level rise of 0.82 mm/year (or 0.032 inch per year) from 2000 through 2011, almost double the rate of the previous decade (Hanna et al., Nature, June 2013).
The author does acknowledge that “a small peninsula on the western coasts has experienced some melting.” This small peninsula, part of the West Antarctic ice sheet, contains enough ice to raise sea level over six feet if fully melted. Recently published results have confirmed that the West Antarctic ice sheet has begun an irreversible collapse (Science, May 16, 2014), but it is not possible yet to state how long this will take.
From these data, as well as hundreds of other peer-reviewed studies, I think it is quite clear that the IPCC is fully justified in its statements about accelerating sea level rise. All of the IPCC Working Group reports are produced by hundreds of leading scientists from around the world and are vetted only by scientist-run review panels, with each reviewer’s comment or criticism responded to.
Calling these scientifically developed reports, which are totally based on peer-reviewed scientific literature, a fraud is indeed a disservice to the IPCC participants and the public at large. It is just one more nonfactual argument from the climate-change denier community that attempts to deceive the public and draw attention away from reality.