Introduction to the Earth Basic Terminology and Concepts Spring 2012, Lecture 1.

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Transcript of Introduction to the Earth Basic Terminology and Concepts Spring 2012, Lecture 1.

  • Introduction to the EarthBasic Terminology and Concepts

    Spring 2012 , Lecture 1

  • *EcosphereThat part of the earth consisting of the atmosphere, hydrosphere, lithosphere, and biosphere

  • *AtmosphereThe gaseous layer which surrounds the earth, and which is held by gravitational attraction. It consists of layers, the bottom ones of which are:Thermosphere > 80 kmMesopauseMesosphere45 - 80 kmStratopauseStratosphere 12 - 45 km TropopauseTroposphere 0 -12 km

  • *HydrosphereEarth's water, in any physical state Gaseous LiquidSolid

  • *LithosphereThe outermost part of the solid earth, consisting of the entire crust and the upper mantle, from the surface to a depth of about 70 kilometers (km)It is stronger and mechanically more rigid than the asthenosphere (70 - 250 km), which lies under it

  • *Interior of the EarthCrust Continental (0-40 km, to a maximum of 100km) Oceanic (0-10 km)Mantle Upper (bottom of crust to 700 km, and includes the transition zone (350 to 700 km) Lower (700 - 2900 km)Core Outer (2900 - 4980 km - liquid iron-nickel)Inner (4980 - 6370 km - solid)

  • *BiosphereInterface layer between earth's crust, atmosphere, and hydrosphere where life is foundIncludes the total ecosystem of the earth

  • *EcosystemCommunity of interacting organisms, of all speciesIncludes interactions of this community with the chemical and physical systems of earth

  • *Human ActivitiesInteract with the natural world, causing changes in the ecosystemChanges vary in magnitude and temporal scale

  • *Environmental IssuesChanges in the ecosphere caused by:Natural processesHuman activitiesOften cause changeAffect the rate at which change occursOr both

  • *Changes By Other SpeciesHumans are not the only species to cause environmental change Cyanobacteria, the first organisms capable of photosynthesis, gradually changed the atmosphere of earth from one without oxygen to one with the present 21% oxygen content

  • *So What Makes Humans Different?Humans are the first species to be aware of their influenceHumans assume, to some extent, responsibility for wise management of the planetHumans affect change at rates unprecedented in the geological record

  • *Technology ImprovementsDuring the last fifty years Have greatly contributed to our awareness of environmental changeEspecially contributing to our knowledge of global scale processesGreatly enhanced out knowledge of the temporal scale of global change

  • *Examples of Technological ChangeSatellite observationsComputational powerRapid communication (Internet)

  • *Changes to the EcosphereMany examples of modification of ecospheric components have been describedRepresentative examples of these modifications are shown on the following slides

  • *Atmospheric ModificationsDepletion of ozone (O3) in the ozone layer (stratosphere) which affects UV light absorptionOzone holeLeads to increased rates of skin cancerAcid deposition introduction of pollutant gasses into the atmosphere leads to the formation of acid rain

  • *Atmospheric Modifications cont.Modification of the climate system by the introduction of greenhouse gasesMajor gases are carbon dioxide, freons, methane, nitrous oxideAre leading to a warmer earth, and will increase number and severity of major stormsMay affect short and medium term climate, and may modify the areas in which food can be grownMay create climate refugees

  • *Hydrological ModificationsDiagram shows a local example of the hydrological cycle

  • *Hydrological Cycle Modifications Withdrawal of waterPollution of waterImpoundment of water (dams) Modifications in erosion and depositional rates Silting of rivers and estuariesIncreased erosion below damsChanges in form of precipitation rain rather than snow

  • *Biosphere ModificationsMobilization and redistribution of chemical elements Most important carbon (C), nitrogen (N), and oxygen (O)Results in enrichment and depletion of various parts of the system, leading to problems like red tide, depletion of soil productivty, etc.

  • *Biosphere Modifications cont.Human activities change natural environmentOften results in changes in species distribution, especially in loss of biological diversity (biodiversity)Rapid expansion of urban and suburban areas decreases available habitatDeforestationExpansion of farming into marginal environmentsLand use that is insensitive to long term changesSalinization

  • *Results of Environmental ChangeSpecies reductionMass mortality - a large number of individuals die, which may lead to a new equilibrium distribution, with a smaller number of individuals of the species in question, or the original equilibrium may be approximately restored, to precatastrophe levels Extinction - A complete elimination of a species. Extinction can and does occur naturally - Man's activities have increased the rate of extinction

  • *Natural EventsNatural events often lead to mass mortality in many species - extinction may occur in severely geographically restricted speciesExamples:EarthquakesVolcanoesTsunamisHurricanes Small meteorite impacts

  • *Large Scale ExtinctionLarge meteorite impacts can result in mass extinctionsExample: Cretaceous-Tertiary event that wiped dinosaurs, and many other species, from the face of the earth Large scale nuclear war would probably have the same effect

  • *Environmental ActionAwareness of environmental change does not always translate to actions favorable to the stabilization of the ecosystemWhy?

  • *Political ProblemsPoliticians make most policy decisions, yet relatively few politicians have any training in science or technologySome overcome this by relying on science/technology advisorsPolitical considerations may cause them to rely more heavily on political or economic advisories, whose perspective is usually focused on a much smaller time scale

  • *Economic GainShort term economic gain is a powerful motiveExample: Drilling for oil in the Arctic Wildlife Preserve will provide profit, and will very temporarily stave off the decline in oil productionThis may make the final decrease in petroleum even more difficult for humans, since we will have built more automobiles, power plants, etc. It will also create immense difficulties for many Arctic species

  • *Sources of PollutionPollution may occur from a variety of sourcesGenerally we can divide pollution sources into two types:Point sources pollution emanating from a single source, such as a power plant smokestackNon-point sources pollution derived from a variety of sources, such as smog from automobile exhaust

  • *Scope of Environmental ProblemsEnvironmental problems are generally split into one of three groups, with the possibility of overlap between groupsLocal effluent introduced into a stream from an industrial plantRegional acid rain in the northeastern U.S., extending into CanadaGlobal Greenhouse gas warming of the planet

    *Pollution across jurisdictional boundaries is often more difficult to control than local pollution

    This is especially true of pollution across international boundaries

    Regulatory authorities need to be aware of this

    International treaties, including legal enforcement, may be required