The weblog The Air Vent has an interesting post titled [h/t to Don Bishop]
The entire post is worth reading. He includes the text, for example,
“So we know increasing CO2 captures more heat in the lower atmosphere and we know that this heat is claimed to be the cause of global warming. Where everything gets real fuzzy is when the energy content of the ocean is taken into consideration. Models do use the ocean heat content, but in order to demonstrate warming, only the energy of the surface ocean layers can be considered. Of course there are layers and layers (pun intended) of papers that discuss the issues, but in reality very little is actually ‘known’.
Why is it important that climate models only look at surface layers? Because subsurface ocean temps exhibit little variance and even with the worst IPCC scenario’s would exhibit little variance from AGW. It is assumed that all ‘significant’ heat comes and goes from the ocean surface. I wonder though if anyone would be able to demonstrate a tenth of a degree change in the deep ocean over the last 100 years? The answer again is we don’t know if it did, but we do know that a 0.1C release of oceanic subsurface energy would measurably change the surface temperature of the earth in that time period. All that would be required would be ocean current changes but we really don’t have a clue if deep ocean current’s have changed. CO2 atmospheric temp change depends on the assumption of stability 0f heat flow from the deeper oceans. I’m not going to spend a lot of time on this but in case you wonder why many of us are skeptics of catastrophic global warming”
As noted by Sam in the first comment, we have raised this issue also including in our papers
Pielke Sr., R.A., 2008: A broader view of the role of humans in the climate system. Physics Today, 61, Vol. 11, 54-55.
Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331-335. https://pielkeclimatesci.files.wordpress.com/2009/10/r-247.pdf
The post on The Air Vent is worth adding to the reasoning why we need to move away from the use of the global average surface temperature anomaly as the metric to diagnose global warming and cooling.