How much is the ocean really warming?
Article first published online: 12 JAN 2007
Copyright 2007 by the American Geophysical Union.
Geophysical Research Letters
Volume 34, Issue 1, January 2007
How to Cite
2007), How much is the ocean really warming? Geophys. Res. Lett., 34, L01610, doi:10.1029/2006GL027834., and (
- Issue published online: 12 JAN 2007
- Article first published online: 12 JAN 2007
- Manuscript Accepted: 20 NOV 2006
- Manuscript Revised: 12 OCT 2006
- Manuscript Received: 10 AUG 2006
- global warming;
- instrumental bias;
- sampling errors
 We use a global hydrographic dataset to study the effect of instrument related biases on the estimates of long-term temperature changes in the global ocean since the 1950s. The largest discrepancies are found between the expendable bathythermographs (XBT) and bottle and CTD data, with XBT temperatures being positively biased by 0.2–0.4°C on average. Since the XBT data are the largest proportion of the dataset, this bias results in a significant World Ocean warming artefact when time periods before and after introduction of XBT are compared. Using bias-corrected XBT data we argue reduces the ocean heat content change since the 1950s by a factor of 0.62. Our estimate of the ocean heat content increase (0–3000 m) between 1957–66 and 1987–96 is 12.8·1022 J. Because of imperfect sampling this estimate has an uncertainty of at least 8·1022 J