The ocean heat graph (Part 1)

This issue was discussed at Judith Curry’s blog, and Lucia’s Blackboard, referring to this post by Lubos Motl, following a post by Stefan Rahmstorf at RealClimate, all before the release of the AR5 report.

In the SPM, the upper ocean heat graph is Figure SPM.3c,

with the caption (on page 6)
(c) change in global mean upper ocean (0–700 m) heat content aligned to 2006−2010, and relative to the mean of all datasets for 1971 …  All time-series (coloured lines indicating different data sets) show annual values, and where assessed, uncertainties are indicated by coloured shading. See Technical Summary Supplementary Material for a listing of the datasets.
[My screen-grabber seems to have changed the colour scheme].

A first stumbling block is that I cannot find anything called “Technical Summary Supplementary Material” – there is a Technical Summary, but it does not have any supplementary material and does not list the datasets. Is this a mistake in the SPM, or is there some more material that has not been released yet? I have asked some IPCC authors; one says he doesn’t know.

In Chapter 3 there is the following version of the figure

which seems to show the same data, and indicates the sources. Here is the caption:
Figure 3.2: a) Observation-based estimates of annual global mean upper (0–700 m) ocean heat content in ZJ (1 ZJ =10^21 Joules) updated from (see legend): (Levitus et al., 2012), (Ishii and Kimoto, 2009), (Domingues et al., 2008), (Palmer et al., 2007), and (Smith and Murphy, 2007). Uncertainties are shaded, and plotted as published (at the one standard error level, except one standard deviation for Levitus, with no uncertainties provided for Smith). Estimates are shifted to align for 2006–2010, five years that are well measured by Argo, and then plotted relative to the resulting mean of all curves for 1971, the starting year for trend calculations.

Spot the difference in wording between the SPM and the main report.

Anyway here are the papers:

Levitus et al 2012,  World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010

Ishii & Kimoto 2009,  Reevaluation of historical ocean heat content variations with time-varying XBT and MBT depth bias corrections

Domingues et al 2008, Improved estimates of upper-ocean warming and multi-decadal sea-level rise

Palmer et al 2007, Isolating the signal of ocean global warming

Smith & Murphy 2007, An objective ocean temperature and salinity analysis using covariances from a global climate model


2 thoughts on “The ocean heat graph (Part 1)

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s