MISREPRESENTATIONS OF SARGASSO SEA TEMPERATURES BY ARTHUR B. ROBINSON ET AL

Keigwin (Science 274:1504–1508, 1996) reconstructed the SST record in the northern Sargasso Sea to document natural climate variability in recent millennia. The annual average SST proxy used δ¹⁸O in planktonic foraminifera in a radiocarbon-dated 1990 Bermuda Rise box core. Keigwin’s Fig. 4B (K4B) shows a 50-year-averaged time series along with four decades of SST measurements from Station S near Bermuda, demonstrating that the Sargasso Sea is now at its warmest in more than 400 years, and well above the most recent box-core temperature. Taken together, Station S and paleo-temperatures suggest there was an acceleration of warming in the 20^th century, though this was not an explicit conclusion of the paper. Keigwin concluded that anthropogenic warming may be superposed on a natural warming trend.

In an unpublished paper circulated with the anti-Kyoto “Oregon Petition,” Robinson et al. (“Environmental Effects of Increased Atmospheric Carbon Dioxide,” 1998) reproduced K4B but (1) omitted Station S data, (2) incorrectly stated that the time series ended in 1975, (3) conflated Sargasso Sea data with global temperature, and (4) falsely claimed that Keigwin showed global temperatures “are still a little below the average for the past 3,000 years.” Keigwin’s Fig. 2 showed that δ¹⁸O has increased over the past 6000 years, so SSTs calculated from those data would have a long term decrease. Thus, it is inappropriate to compare present-day SST to a long term mean unless the trend is removed. Slight variations of Robinson et al. (1998) have been repeatedly published with different author rotations. Various mislabeled, improperly-drawn, and distorted versions of K4B have appeared in the Wall Street Journal, in weblogs, and even as an editorial cartoon—all supporting baseless claims that current temperatures are lower than the long-term mean, and traceable to Robinson’s misrepresentation with Station S data removed. In 2007, Robinson added a fictitious 2006 temperature that is significantly lower than the measured data. This doctored version of K4B with fabricated data was reprinted in a 2008 Heartland Institute advocacy report, “Nature, Not Human Activity, Rules the Climate.”

Sandia is a multiprogram laboratory operated by Sandia Corp., a Lockheed Martin Company, for the US Dept. of Energy under Contract DE-AC04-94AL85000.