The ocean plays a fundamental role in the establishment of our climate. The meaning of fundamental is clear: a central or primary base or core on which something is based. Michele Fieux et al acknowledge in their essay “Ocean-atmosphere exchanges and water mass formation” that the ocean is a core player to establish climate. That is a clear statement but unfortunately not reflected in the essay. Too superficial, and too little focus on the oceans dimension (Fig.1).
On one hand it is certainly necessary to mention that ‘the ocean is heated from above’. But if the ocean covers 71% of the Earth’s surface and represents more than 96% of the Earth’s free water, it is incredible negligent not to elaborate on the fact that the mean ocean temperature is a low as 4° Celsius.
It is of course correct to mention that the ocean-atmosphere fluid ensemble is an immense thermal machine fueled by the sun, resulting in particular strong thermal stratification in the surface layer, but a failure not to discuss that the immediate sun induced sea surface layer comprise at maximum only few dozen meters, neither to mention the role of salinity, which may vary significantly due to precipitation. The aspect of rain is important as it is fresh-water, which usually ‘swim’ above saltier and colder water for some time, until wind and ocean human uses (shipping, fishing etc) start mixing the surface layer.
The essay is close to wrong when stating that these heat and water losses (at the sea surface) have significant consequences, particularly for deep-ocean circulation, as by far the main criteria are differences in temperature and salinity. Even the smallest differences contribute to the motion of the huge ocean water body, which results in a global deep-ocean circulation system that requires up to thousands of years to complete a global circumnavigation.
Michele Fieux et al conclude their essay asserting that:
The ocean plays a fundamental role in the establishment of our climate. It stores solar energy, transports it, and transmits it to the atmosphere. It thus helps diminish climate contrasts. Ocean circulation is the main climate-regulating process on the surface of our planet. The ocean provides the short, medium and very long term ‘memory’ of the atmosphere.
The last sentence reveals that the authors understanding of our global climate system is fuzzy. The atmosphere and its influence (although important for man due to weather conditions) is a mere appendix in this system, while the ocean provides the short, medium and very long term climatic condition on this planet. Not being very clear leads to the often heard dumb notion that “Predicting Climate is Easier than Predicting Weather”, or more detailed:
Climate is average weather, which is more predictable than day-to-day and hour-to-hour weather changes. Weather behaviour is chaotic and often difficult to predict beyond a week or so into the future. By comparison, climate is largely determined by global and regional geophysical processes that change slowly. Hence, if these factors are properly understood and predictable, then the climate can be forecast far into the future with a significant degree of confidence.*)
Anyone who is willing and able to recognize how little is known about the ocean and how little data are available for any reliably assessment, will reject the statement as unreasonable chatter.
According to the United Nation’s Intergovernmental Panel on Climate Change (IPCC), the atmosphere accounts for only 1% of the heat energy change in the Earth system, whereas the 0-2000 meter layer of the ocean is where 93% of the globe’s overall heat/temperature change has occurred in recent decades.