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Can Naval War be ignored when the collected SST are “out of tune”?

Original Figure from:

Thompson, Kennedy, Wallace & Jones; 2008, Nature, V.453/P.246  (Summary)

A large discontinuity in the mid-twentieth century in observed global-mean surface temperature.

Data sets used to monitor the Earth's climate indicate that the surface of the Earth warmed from 1910 to 1940, cooled slightly from 1940 to 1970, and then warmed markedly from 1970 onward. The weak cooling apparent in the middle part of the century has been interpreted in the context of a variety of physical factors, such as atmosphere–ocean interactions and anthropogenic emissions of sulphate aerosols. Here we call attention to a previously overlooked discontinuity in the record at 1945, which is a prominent feature of the cooling trend in the mid-twentieth century. The discontinuity is evident in published versions of the global-mean temperature time series1, but stands out more clearly after the data are filtered for the effects of internal climate variability. We argue that the abrupt temperature drop of 0.3 °C in 1945 is the apparent result of uncorrected instrumental biases in the sea surface temperature record. Corrections for the discontinuity are expected to alter the character of mid-twentieth century temperature variability but not estimates of the century-long trend in global-mean temperatures.

COMMENT: The data have been discussed frequently (e.g. Wright 1986;  Folland & Parker, 1995), and the use of WWII data is highly questionable anyhow (Bernaerts, WWII-SST-Pacific 1997 & WWII-SST-Atlantic 1998). It surprises that Thompson et al. do not even consider the impact the naval war may have had on the SST. Bob Tisdale discusses their result and point to the increased cloudiness during WWII, concluding:

 Unless the datasets were used to infill one another during the 1940s, or unless the "bucket adjustments" also somehow magically apply to Marine Air Temperature and Cloud Cover data, the similarities in the shifts of the SST , the Cloud Cover and the Marine Air Temperature datasets would make one question the conclusions of the Thompson et al (2008) paper.

Chapter: 4_11

Book Page: 213a

File: none