Learn how plants respond to higher atmospheric CO2 concentrations

How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic


A Comparison of Modeled and Observed Sea Surface Temperatures

Paper Reviewed
Laepple, T. and Huybers, P. 2014b. Ocean surface temperature variability: Large model-data differences at decadal and longer periods. Proceedings of the National Academy of Sciences USA 111: 16,682-16,687.

Introducing their study of the subject, Laepple and Huybers (2014b) write that "variations in sea surface temperature (SST) have widespread implications for society and are the basis of most regional decadal prediction efforts." This relationship works fine at synoptic and interannual timescales, where they say there is overall agreement between observational and General Circulation Model (GCM) estimates of SST variability. But at decadal timescales they say instrumental records typically show greater regional SST variability than what is found to be the case with the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble of GCM simulations, as they themselves had recently demonstrated (Laepple and Huybers, 2014a) and as had earlier been shown would likely be the case by Stott and Tett (1998), Davey et al. (2002) and DelSole (2006).

Because of what had been learned from these short-term studies, the two U.S. researchers went on to analyze 33 high-resolution proxy temperature records that had been reconstructed, based on materials found in lengthy marine sediment cores, some of which extended back in time as much as 7,000 years. And these results, as they report, "indicate that centennial and millennial variations are substantially larger than those found at decadal timescales, as has been previously noted," citing the studies of deMenocal et al. (2000), Huybers and Curry (2006), Black et al. (2007) and Sachs (2007).

So just how big is substantially larger? Quoting Laepple and Huybers, the "discrepancies in variability are largest at low latitudes ... reaching two orders of magnitude for tropical variability at millennial timescales." And because a discrepancy of two orders of magnitude is difficult to ignore, they say their result "implies major deficiencies in observational estimates or model simulations, or both, and has implications for the attribution of past variations and prediction of future change."

And we still find people declaring that the science is settled????? In no way is this the case.

References
Black, D.E., Abahazi, M.A., Thunell, R.C., Kaplan,A., Tappa, E.J. and Peterson, L.C. 2007. An 8-century tropical Atlantic SST record from the Cariaco Basin: Baseline variability, twentieth-century warming, and Atlantic hurricane frequency. Paleoceanography 22: PA4204.

Davey, M., Huddleston, M., Sperber, K.R., Braconnot, P., Bryan, F., Chen, D., Colman, R.A., Cooper, C., Cubasch, U., Delecluse, P., DeWitt, D., Fairhead, L., Flato, G., Gordon, C., Hogan, T., Ji, M., Kimoto, M., Kitoh, A., Knutson, T. R., Latif, M., Le Treut, H., Li, T., Manabe, S., Mechoso, C. R., Meehl, G. A., Power, S. B., Roeckner, E., Terray, L., Vintzileos, A., Voss, R., Wang, B., Washington, W. M., Yoshikawa, I., Yu, J.Y., Yukimoto, S. and Zebiak, S.E. 2002. STOIC: A study of coupled model climatology and variability in tropical ocean regions. Climate Dynamics 18: 403-420.

DelSole, T. 2006. Low-frequency variations of surface temperature in observations and simulations. Journal of Climate 19: 4487-4507.

deMenocal, P., Ortiz, J., Guilderson, T. and Sarnthein, M. 2000. Coherent high- and low-latitude climate variability during the Holocene warm period. Science 288: 2188-2202.

Huybers, P. and Curry, W. 2006. Links between annual, Milankovitch and continuum temperature variability. Nature 441: 329-332.

Laepple, T. and Huybers, P. 2014a. Global and regional variability in marine surface temperatures. Geophysical Research Letters 41: 2528-25 34.

Sachs, J. 2007. Cooling of Northwest Atlantic slope waters during the Holocene. Geophysical Research Letters 34: 10.1029/2006GL028495.

Stott, P.A. and Tett, S.F.B. 1998. Scale-dependent detection of climate change. Journal of Climate 11: 3282-3294.

Posted 30 March 2015