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Joseph F. Donoghue[dagger] and Randall W. Parkinson[double dagger]
[dagger]Department of Earth
Ocean and Atmospheric Science
Florida State University
108 Carraway Building
Tallahassee, FL 32306, U.S.A.
jfdonoghue@fsu.edu
[double dagger]RWParkinson Consulting, Inc.
2018 Melbourne Court, Suite 205
Melbourne, FL 32901, U.S.A.
rwparkinson@cfl.rr.com
DOI: 10.2112/JCOASTRES-D-11-00098.1 received 16 May 2011; accepted in revision 22 May 2011.
Published Pre-print online 18 July 2011.
© Coastal Education & Research Foundation 2011
INTRODUCTION
In a recent article, Houston and Dean (2011) attempted to quantify acceleration in the rate of historical sea-level rise (SLR) by analyzing monthly averaged, long-term, tide-gauge records for 57 U.S. tide stations. The data were extracted from the Permanent Service for Mean Sea Level (PSMSL) at the National Oceanography Centre in Liverpool, U.K. The investigation involved the calculation of accelerations for each station for the period of record, plus accelerations for the 25 stations whose records extended back to 1930. The authors calculated decelerations, i.e., a slowing in the rate of SLR, for 16 of the 25 selected long-term gauge records. The authors stated that there is no evidence of acceleration in 20th century SLR, despite rising atmospheric temperatures. Therefore, they contended the accelerations forecasted to accompany continued warming are highly suspect. They concluded that researchers must now determine why global warming has not produced an acceleration in SLR. We believe the authors' conclusions are erroneous for a variety of reasons, including those argued in the accompanying rebuttals. We will focus our criticism on three issues in the sections that follow.
GEOGRAPHIC AND TEMPORAL LIMITITATIONS OF THE TIDE-GAUGE DATA
There are approximately 1800 global tide stations with reasonably long records in the PSMSL database that the authors accessed. The authors initially selected just 57 stations, and later reduced the number analyzed to 25 stations. The gauge locations were only in the United States. Additionally, the authors used data collected between 1930 and 2009, despite the fact that many of the PSMSL data sets extend back well beyond 100 years. Jevrejeva et al. (2006) employed advanced statistical analyses to examine the PSMSL tide gauge database and found that determining the rate of SLR was highly dependent on the time period chosen. They further noted large decadal-scale and regional variability in the global tide-gauge record, a variability that has increased toward...