title: The earth and its life: systems perspective.
abstract: From the planetary point of view, the Earth can be imagined as a system comprised of interwined natural populations propagated through time via recycling. This recycling, or 'birth/death' process, imposes age patterns on natural populations of the solid earth, hydrosphere, atmosphere and living entities. Mathematically, the concept is analogous to that of population dynamics in living systems. The populations of the Earth system form a hierarchical structure. The hierarchy of geological tectonic realms contains populations of less than or equal to 10(24)-10(26) gr in size, with half-lives in the 10(7)-10(9) yr time range. The approximate parameters for the oceans are less than or equal to 10(24) gr and 10(2)-10(7) yr, for the atmosphere less than or equal to 10(21) gr and 10(-2)-10(7) yr, and for living systems less than or equal to 10(14)-10(19) gr and 10(-3)-10(-2) yr, respectively. In this perspective, and in departure from the GAIA hypothesis, the subordinate populations, such as those of living systems, are constrained to operate within limits imposed by the larger, and slower, hierarchies. They can overstep the imposed limits only on time scales shorter than the response time of the dominant populations. Isotopic record of past sea water shows that on time scales of 10(7) yr the solid earth, hydrosphere, atmosphere and life act as a unified system controlled by tectonics, that is by the hierarchy of the solid earth.
authors: Derry Laboratory, Department of Geology, University of Ottawa, Ontario, Canada.
authors: J
authors: J
authors: Veizer
mesh_terms: D005075:Biological Evolution; D055593:Geological Phenomena; D005844:Geology; D000069497:Origin of Life; D012623:Seawater