“Differences between ocean circulation and climate more generally” by Carl Wunsch 2010

Judith Curry raises the part to the sociology of
climate science only. The oceans are what matters most.

Post July 25th, 2018

Talking about the difference between ocean circulation and climate more generally is per se a strong massage that there is a strong correlation. Back in 1984 Carl Wunsch discussed the matter already lengthy in: ”The Global Climate”, ed. John T. Houghton, Cambridge p.189-203).  He raises a number of topics, saying for example: “The role of the ocean in climate and climate change is unlikely to be demonstrated and understood until observations become meaningful in terms of physics being tested” (p.189); and “There is no substitute for adequate data”, (p.200).

More recently Carl Wunsch published the paper “Towards Understanding the Paleocean” (Quaternary Science Review, 2010, p. 1960-1967).  Almost a decade late the paper surfaced due to Prof. Judith Curry while doing a literature survey for a paper on Climate Uncertainty and Risk. As she regarded the paper by the esteemed oceanographer for a fascinating perspective on paleo-oceanography and paleoclimatology, she used it for a post on her blog Climate Etc.; titled: ”The perils of ‘near-tabloid science’” on July 22, 2018. Unfortunately she chooses a one-sided approach by selecting only excerpts of relevance to the sociology of climate science. The oceanic part is completely neglected, although the Wunsch paper expresses the view understanding the dynamics and physics of the ocean is a perquisite for predicting future climate. Merely concentration on the sociology of climate science indicates to the fundamental problems in the climate change debate is distracting from the core issue of climate: the oceans. One need only to read the comments to Curry’s post at Climate Etc. & WUWT. The ocean issue is not discussed.

Carl Wunsch has raised the need for ocean observation throughout his career as oceanographer (see above). In his essay of 2010 he mention inter alias:

__ Myriad hypotheses have been put forward as rationalizing some elements of the oceanic role in

influencing climate–ranging over essentially all possible time scales out to the age of the ocean. One cannot begin to discuss all of these, and so I will here take as a not-untypical example, the hypothesis that the North Atlantic circulation largely controls the climate system, and in particular, the notion that the surface salinity is the determining influence.

­­___ As with future climate, where no data exist at all, the models promise descriptions of climate change –past and future– without the painful necessity of obtaining supporting observations.

­­___ The study of paleoclimate encompasses such a huge range of problems, methods, regions, phenomena, time and space scales, that no one has mastered it all. With that complexity, any science runs the risk of becoming so abstract, or so devoted to particular stories, or both, that they lose relevance to the physical world.

In his previous essay “OBSERVATIONAL NETWORK DESIGN FOR CLIMATE”, 2009, the list of requirements is even more detailed (excerpts):

(1)  The  problems  of  climate  are  global:  understanding of the nature of the mean ocean, and its variability cannot  ultimately  be  isolated  from  even  remote  regions. Dependence on distant regions is only weakly a function of the space-time scale of any particular disturbance —in many  cases,  signals  of  change  are  transmitted  globally extremely  rapidly,  but  with  final  equilibrium  requiring decades to thousands of years.

(2) Any true global observing system will be an amalgam of disparate elements such as altimeters, drifters, gliders, floats, and moorings.

(3)  True understanding of the climate system can be claimed only if all the observations are considered (….).

(4) True understanding of the climate system requires a synthesis of the disparate data types with the dynamics believed to govern the system.  (5)  ….

(6) Quantitative use of data and models cannot be done without adequate knowledge of the likely errors of both. (7…; 8….)

 (9) Any useful ocean observation system must be open ended in time—there is no low-frequency cut-off to the time scales over which the system is capable of change, and  new  physics  always  enters  as  the  time  scale  increases.  Much  of  what  we  see  today  may  well  be  the result  of  changes  and  forces  acting  in  the  distant  past. Design considerations must thus include the ability to sustain a high quality system indefinitely so that those long times are ultimately observed.

Carl Wunsch’s message is explicit. Without an in-depth, profound and long lasting ocean observing system the climate change debate remains an unsolved and shaky debate.

While working on this post Ron Clutz referred to a report in May 2015 The Atlantic is entering a cool phase that will change the world’s weather by Gerald McCarthy and Evan Haigh of the RAPID Atlantic monitoring project.
The oceans are what matters most.

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