Module C

Module C - Module C. The Earth Machine: Linking the Spheres...

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Unformatted text preview: Module C. The Earth Machine: Linking the Spheres Lesson 7. Introduction to Systems Science Introduction As we covered briefly in Lesson 1, Module A, the field of Earth System Science views our planet as the interaction of many interacting elements (or systems) - like the components of a large machine or the organs of a creature. In the figure below, the biosphere (life), the hydrosphere (including all Earth's water including oceans, rivers, lakes and ice), and the atmosphere are shown. Some scientists give ice its own separate "sphere", the cryosphere, while others define a separate unit based on the activities and presence of man, the "anthrosphere" (also called the "anthroposphere"). An understanding of the interaction of all these elements or spheres will help us in our studies of the Mesozoic atmosphere and oceans and perhaps put current climate change in more of a geological context. Systems Theory To properly use the paradigm of Earth System Science as a tool to investigate Mesozoic or present-day oceans and atmospheres, we need to understand what we mean by "systems". A system is defined as any portion of the Universe that can be isolated from the rest of the Universe for the purposes of observing and measuring. A system therefore can be whatever you chose it to be. For example, a leaf is a system that is part of a tree, a tree is part of a larger forest system and a forest is part of an even larger global ecosystem. Systems Theory aims to construct models that are universally applicable to the natural physical or social sciences. Figure C-1. Otway Fly Canopy Walk, Victoria, Australia A forest is a complex ecosystem composed of many integrated "systems". Photo by S. Sutherland. Let's use a glass of water as an example of a system (see figure below). If we place the glass of water into an airtight, heatproof container, we can consider it to be an isolated system: there is no exchange of matter or energy between the glass of water and the environment or systems outside the container. If we take the glass of water out of the container but keep an airtight lid on the glass then this is more like a closed system: there is an exchange of energy (in the form of light and heat through the glass) but no exchange of matter. If we take the blue lid off the glass of water we create an open system in which there is a free exchange of energy and matter between the glass of water and the external environment/systems. Figure C-3. Examples of systems in nature. The International Space Station (top left) is an isolated system, the Earth (right) is a closed system, while the Earth's ocean (bottom left) is an open system, as it continuously interacts with the terrestrial and atmospheric systems. In nature, it is very difficult to find isolated systems. Space stations or spacecraft may be considered isolated systems, as they have to be isolated from the external environment. These are not perfect isolated systems though as they still need to receive supplies from another system (Earth) to be maintained. receive supplies from another system (Earth) to be maintained....
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This note was uploaded on 11/18/2011 for the course EOSC 116 taught by Professor Randell during the Winter '09 term at UBC.

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Module C - Module C. The Earth Machine: Linking the Spheres...

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