The Earth System

This book also tracks the changes in the Earth from its primordial state to the time at which modern processes were established. Whilst this time is not exactly known there is 

Forty years ago, our understanding of how the Earth works was revolutionized by the theory of Plate Tectonics. This theory, however, only described the workings of the solid Earth, with a particular emphasis on the origin of ocean basins and active mountain belts. In contrast, Earth System Science is about much 

Lovelock s great insight was to recognize that life affects the global environment and profoundly affects surficial processes on the Earth. Thus when the Earth System is perturbed, either from outer space or from the interior of the Earth, the Earth s self-regulatory systems come into play, eventually restoring the system to its original conditions. This makes the Earth Surface System resilient to all but the most extreme perturbations. Lovelock and subsequent workers have illustrated this process with a simple model which they called Daisyworld.  

Daisyworld is a computer model of a simplified Earth in which variation in the Earth System is described by one parameter, surface temperature, which in turn is affected by a 

Systems approach not only includes solid Earth processes such as the origin and motion of continents and the creation and destruction of ocean basins, but also the origin and evolution of life and the changing pattern of the Earth s climate through time. 

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The earth systems associated with high-voltage substations must satisfy the following conditions ... 

The Philosophy of Integration as a Basis for Understanding the Earth System... 

It is often important to know how long an element spends in one environment before it is transported somewhere else in the Earth system. For example, if a time scale characterizing a chemical or physical transformation process in a region has been estimated, a comparison with the time scale characterizing the transport away from the region will tell which process is likely to dominate. 

Before proceeding through a hierarchy of examples, a word about the term equilibrium is in order, particularly as it applies to the dynamically changing components of the Earth system. It is a fact that any particular chemical system itself will rarely be in true equilibrium, just as the physical systems of Earth are not ever really in a perfect steady state. The equilibrium conditions are extremely relevant because they describe the tendency of the system to which termodynamically favorable reactions tend. That is, no matter what the condition is, all systems are moving toward equilibrium. 

Not surprisingly, the acid-base balances within the Earth system almost all involve elements of high abundance, i.e., elements that have low atomic number. In many cases, the acidic molecule is an oxygen-containing oxidation product of an element. Table 16-1 lists the main acids and bases in the global environment. The sources of these acids are chemical reactions of reduced forms of the element involved. Both gas and aqueous phase reactions exist for production of acids. 

Table 16-1 Dominant acids and bases in the Earth system...

Recent revisions to the boundary conditions (ice-sheet topography and sea surface temperatures) have added uncertainty to many of the GCM calculations of the past two decades. Moreover, all of these calculations use prescriptions for at least one central component of the climate system, generally oceanic heat transport and/or sea surface temperatures. This limits the predictive benefit of the models. Nonetheless, these models are the only appropriate way to integrate physical models of diverse aspects of the Earth systems into a unified climate prediction tool. 

Human Modification of the Earth System Global Change... 

I apply these computational methods to various aspects of the Earth system, including the responses of ocean and atmosphere to the combustion of fossil fuels, the influence of biological activity on the variation of seawater composition between ocean basins, the oxidation-reduction balance of the deep sea, perturbations of the climate system and their effect on surface temperatures, carbon isotopes and the influence of fossil fuel combustion, the effect of evaporation on the composition of seawater, and diagenesis in carbonate sediments. These applications have not been fully developed as research studies rather, they are presented as potentially interesting applications of the computational methods. 

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