ABSTRACT
Fivemajorcomponentsarebelievedtodeterminetheclimate: theatmosphere(∼100kmblanketofgassesaroundtheearth), hydrosphere(encompassingallwaterbodiesfromaquifersto clouds,e.g.,lakes,streams,andoceans),lithosphere(upperpartof
the solid earth, containing sediments, rocks, and soil), biosphere (regions that sustain life, covering the lithosphere, portions of the hydrosphere, and the lower atmosphere), and cryosphere (ice, snow, glaciers, and permafrost; it holds ∼2% of the water supply, covering 5.7% of the earth’s surface). Common constituents, transformations, interactions, and feedbacks intertwine these spheres. For example, melting of the cryosphere would raise the sea level by tens of meters, shut o§ thermohaline circulation of oceans, and drastically change weather patterns and heat distribution in the atmosphere. Oceans, the major component of the hydrosphere, contain ∼97% of the world’s water supply. ›ey cover 75% of the earth surface with an average depth of 3.7km,maximumdepthof11km(Marianatrench),andamass of1.4×1021 kg (Gill 1982). Oceans are also the dominant reservoirsofcarbonandhencearecentraltotheunderstandingof climatevariability(SarmientoandGruber2002).›eintersectionofthebiospherewithothermajorclimaticspheres,with lithosphereastheplatform,iscalledtheecosphereorsimply put-ourEnvironment(Figure1.1).›ephysicalandbiological (humans,plants,animals,andmicroorganisms)aspectsofthe ecosphere are studied in Ecology (Odum 1971).
