In the Real Climate post
in answer to the question by Dan H.
“……any comment as to why the ocean heat content has appeared to level off during the post 2003 period?”
“As for OHC, it is likely to be a combination of internal variability, not accounting for heat increases below 700m, and issues with the observing system – compare to the Lyman et al analysis. More time is required for that to become clear.”
Gavin, unfortunately, too cavalierly dismisses this issue. First, if the leveling off of OHC is due to internal variability, than the GISS, and other models have failed to skillfully simulate this behavior. Where have the models predicted this muting of upper ocean heating over a six year time scale (and counting).
Second, if the heating has increased below 700m, why was the transfer of this heat through the 0-700m depths not seen in the Argo data?
Finally, perhaps there are remaining problems with the observing system. Neither Gavin or I are an expert on this subject. However, I do have expertise in the assessment in the long term monitoring of surface air temperature trends; e.g. see
Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.
Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2009: An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841.
Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2010: Correction to: “An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841″, J. Geophys. Res., 115, D1, doi:10.1029/2009JD013655.
Gavin is selective in the validation information he uses to compare with the GISS model results. He used the surface temperature trend data since it bolsters his conclusions, but fails to discuss the systematic warm bias that has been found in that data.
What is needed are independent assessments of the skill at these models at predicting climate metrics including upper ocean heat content .