In order to catch a glimpse of the current balance and complexity of feedback loops, we look at the coccolithophore, a marine algae, resident of the layer of the ocean plankton. This thin layer of tiny, drifting creatures in the top several feet of the ocean, is the beginning of the ocean food web, where incoming sunlight is turned into food for all the succeeding levels of life in the ocean. The plankton has a wide variety of members, from a host of viruses and bacteria up through larval forms of much larger sea creatures.
The coccolithophores, however, are a large part of the oxygen producing algae, and can form nation-sized blooms in a matter of days. Individually they are covered with intricate shields of calcite. Each shield is secreted in vesicles in the algae cell and then transported to the surface of the cell. The purpose of these circular calcite disks is still debated.
These cells both use and emit CO2, as well as O2 and dissolved acid. They also give off a gas called dimethyl sulfide. Since they occur in large numbers, they are studied for their effect on the large scale cycles of all of the above chemicals. On the geological scale of time, they deposit about half of the calcite which later becomes limestone and marble. As such, they are a major player in the temperature control system that sees lichens and bacteria on the land digesting rock to produce carbonate ion that is washed to the ocean, which is deposited by these same coccolithophores. Thus over time, CO2 leaves the atmosphere. This cycle has kept us cool for hundreds of millions of years. (To be clear, the coccolithophores have only been active for the last 65 million years, and other algae had the same role before.) These cells are also part of shorter-term cycles of oxygen and carbon dioxide in the atmosphere, and the acidity of the water. Because all these processes occur simultaneously within the same cell, scientists are not yet clear on their net effect on the larger systems. Beyond affecting the CO2 concentration, which influences the temperature, coccolithophores also produce a gas called dimethyl sulfide which encourages cloud formation. This contributes to a negative feedback cycle. More dimethyl sulfide is produced as the temperature rises, which encourages more clouds. This shields the ocean from incoming sunlight, and thus causes the temperature to fall.
The illustration of the coccolithophores is useful to show the complexity and the fine tuning that may result from interlocking feedback loops. Acknowledging that these loops are not, in fact, separate but influence each other, can lead to an almost vertiginous acknowledgement of an interlocking complexity that is far beyond logical comprehension. We saw that a similar incomprehensible complexity inside the human body does not prevent us from knowing about and relating to the emergent identity of the whole person.
Having looked at several larger scale balances and emergent properties in this book, it is proposed that the action of cooperation produces an entity at the largest level. It is also possible that, as humans, we may need to search for other ways to understand an entity on this scale.