The oceans are the only thing keeping atmospheric temperatures and its oxygen content within habitable limits.
Oceans moderate the temperature two ways. First water has very high heat capacity, which is the ability to absorb heat energy while resisting temperature change. The ocean’s heat capacity also allows the thermohaline circulation to move large quantities of heat from the equator, where it is accumulated, towards the poles, where until man started adding greenhouse gases to the atmosphere average global temperature equilibrium was maintain, for the most part, by radiating the heat back to space.
Indicative of the kind of heat that is moved in this process; in the Atlantic the thermohaline moves about 1.2 petawatts of heat, about 100 times the global demand for energy, northward.
The Earth’s poles are warming twice as fast as the rest of the planet because of energy in the atmosphere carried by large weather systems also moving heat from the warm to the cold in accordance with the laws of thermodynamics.
Heat capacity is measure in terms of joules per gram per degree Celsius. The greater the mass of a body the more heat is required to raise the temperature of that body one degree.
The atmosphere has a mass of about 5.15×1018 kilograms.
The total mass of the oceans is about 1.37×1021 kilograms and since the heat capacity of water is 4 times that of air they have over 1000 times the capability to absorb heat that the atmosphere does.
The Paris climate summit set the limit for global warming at 2 degrees Celsius over pre-industrial temperatures with aspirations for an even lower 1.5 degree increase.
When measuring climate change the temperature is taken or reconstructed for the Earth’s surface, and that of the seas.
Three quarters of the atmosphere lies within 11 kilometers of the Earth’s surface and it becomes increasingly thinner and colder with altitude. Even with its limited heat capacity in comparison to the oceans it is warmest at the surface where temperatures are taken and above that it has increasingly less and less capacity to hold heat.
The average depth of the oceans is 3.7 kilometers and as can be seen from the following diagram its density increases to a depth of 1 kilometer and remains constant beyond that.
The following NOAA diagram shows the typical seawater temperature profile of the ocean.
The thermocline is the red line showing the rapid temperature decrease below 200 meters to 1 kilometer below which the temperature ranges from near freezing to just above the freezing point of water.
It should be clear from these two diagrams that beyond the surface, where its temperature is taken, the oceans have a huge and untapped capacity to absorb the heat of global warming and the thermodynamics as shown in the following diagram dictate that the movement of that heat into this void through a heat engine allows for the production of at least as much energy as is currently derived from fossil fuels.
The alternative to taking this action is foretold in the following headlines:
In the first instance water is delivered concurrently with energy when the energy from the ocean heat engine is converted to the energy/water carrier hydrogen by electrolysis.
In the second case atmospheric temperatures are maintained within life sustaining limits by moving the excess heat into the ocean abyss.
Finally the oxygen threat stems from the demise of phytoplankton deprived of the nutrients they need to survive by thermal stratification and the unsustainable heat buildup in the euphotic zone, or layer near the surface that receives enough sunlight for them to produce oxygen through photosynthesis. Both of these conditions are also remedied by moving heat away from the ocean’s surface and into the deep.
And if these prospects aren’t enough to precipitate the action necessary to address climate change, a recent study by James Hansen and 17 colleagues suggests that the thermohaline circulation and its capacity to ventilate heat to the atmosphere and space can be altered by freshwater injection from ice sheets which put a lid on the process.
Here too much of the heat that is causing the ice sheets to melt can be productively sequestered in the deep.
A number of scientists, here and here have faulted the Paris conference for making commitments in the absence of a plan to reach the stated goals and in fact committing the parties and their political capital to half measures. The pre-submitted plans of the parties to the agreement currently add up to a 2.7 degree increase by the end of the century, at best.
An even greater problem however is that there are some who believe that because the oceans absorb 90% of the excess heat of global warming and 25% of the carbon produced by burning fossil fuels and are the source of oxygen and much of the world’s food supply they should be ring fenced and cut off from the very actions that could save them, the life forms that reside within them and ourselves from irreparable harm.