Empirical evidence for a global atmospheric temperature control system: physical structure

There is evidence that a natural control system influences global atmospheric surface temperature (Leggett and Ball 2020). The present paper sets up and tests a hypothesis concerning the physical makeup of the sequential elements of the control system and its outcomes. The final outcome that the control system influences is defined as global atmospheric surface temperature. The terms used for the control system element types in the hypothesis are, in sequence: leading element, controller and actuator. Actuators are hypothesised to affect, in turn, the final outcome – either directly, or via penultimate outcomes. The existence of the control system is evidenced by demonstration of statistically significant one-way Granger causality across each step of the hypothesised control system sequence. Evidence is presented that the leading element of the control system, represented by the Normalized Difference Vegetation Index, is the global biosphere. The biosphere as a control system has previously been referred to as Gaia (Lovelock and Margulis 1974). A fourth, second-derivative, term is found to enhance the Proportional, Integral and Derivative process terms of the control system shown in Leggett and Ball (2020). The main actuators of the control system found are shown to be wind speed and cloud cover. Cloud cover is shown to influence the final outcome, global surface temperature, directly. It and wind speed also influence the penultimate outcomes found, those of enhanced ocean heat uptake and enhanced outgoing longwave radiation. These together lead to control system output to the final outcome, global atmospheric temperature. Overall, evidence for the activity of the control system is shown to be present across many major physical dimensions of the Earth’s atmosphere.