2011-01-14 14:18:49New paper on deep ocean warming
John Cook


I asked Catia Domingues (local Aussie ocean heat expert) re the ocean warming issue and she pointed me to a paper that's currently in press that raised my eyebrows. I've bolded the eyebrow lifting part of the abstract.

Deep ocean warming assessed from altimeters, Gravity Recovery and Climate Experiment, in situ measurements, and a non-Boussinesq ocean general circulation model, Song, Y. T., and F. Colberg (2011)
Observational surveys have shown significant oceanic bottom-water warming, but they are too spatially and temporally sporadic to quantify the deep ocean contribution to the present day sea-level rise (SLR). In this study, altimetry sea surface height (SSH), GRACE ocean mass, and in-situ upper-ocean (0-700m) steric height have been assessed for their seasonal variability and trend maps. It is shown that neither the global mean nor the regional trends of altimetry SLR can be explained by the upper-ocean steric height plus the GRACE ocean mass. A non-Boussinesq ocean general circulation model (OGCM), allowing the sea-level to rise as a direct response to the heat added into the ocean, is then used to diagnose the deep-ocean steric height. Constrained by sea-surface temperature data and the top-of-atmosphere (TOA) radiation measurements, the model reproduces the observed upper-ocean heat content well. Combining the modeled deepocean steric height with observational upper-ocean data gives the full-depth steric height. Adding a GRACE-estimated mass trend, the data-model combination explains not only the altimetry global mean SLR but also its regional trends fairly well. The deep ocean warming is mostly prevalent in the Atlantic and Indian Oceans, and along the Antarctic Circumpolar Current, suggesting a strong relation to the oceanic circulation and dynamics. Its comparison with available bottom-water measurements shows reasonably agreement, indicating that deep-ocean warming below 700 m might have contributed 1.1 mm/year to the global mean SLR or one-third of the altimeter-observed rate of 3.11±0.6 mm/year over 1993-2008.

It's always been my understanding that deep ocean warming can only have contributed a small portion of sea level rise. So this new result is a bit surprise (or maybe I just had it wrong this whole time). If anyone wants the full paper, email me at john@skepticalscience.com

2011-01-14 18:18:46
Ari Jokimäki

With a quick glance this seems to support very well the Purkey & Johnson (2010) study. The spatial distribution of the warming seems to be similar as in P&J.
2011-01-14 19:12:03
Rob Painting

Ken Lambert will not be happy...... not happy at all. I know what he'll say though, "How did the heat get down there when the top 700 meters is so well monitored?"......cue fudging data etc.

Glad that progress is being made on this, OHC is one of those "skeptic" memes that has always bugged me.  

2011-01-14 21:29:19

You won't stop skeptics for a while. The problem is that we know that the heat is probably there but no one has figured out how it can go there. It is important, though, to measure it and provide the necessary evidence.
2011-01-15 00:50:14
Ari Jokimäki

Both Purkey & Johnson and this new study seem to suggest the same thing - that the deep ocean is warmed by the ocean circulation. The warm surface water is going deep in Southern Ocean and spread elsewhere from there.
2011-01-18 10:23:08
Glenn Tamblyn



I wonder how well this fits into Kevin Trenberth's missing energy?