Environmental Problems, Their Causes, and Sustainability 1

changes that lead to an increasingly interconnectedworld. It involves increasing exchanges of people,products, services, capital, and ideas across internationalborders.Factors accelerating globalization include informationand communication technologies, human mobility,and international trade and investment. Moderncommunication via cell phones and the Internet alsoallows powerless people throughout the world toshare ideas and to band together to bring about changefrom the bottom up.This decentralized network, where everyone hasaccess to everyone else, represents a democratization oflearning and communication that is unprecedented inhuman history. A sustainable community or countryrecognizes that it is part of a larger global economicand ecological system and that it cannot be sustainableunless these larger systems are also sustainable.DirectsolarenergyPerpetualWinds,tides,flowingwaterResourcesRenewableFossilfuels(oil,naturalgas,coal)NonrenewableMetallicminerals(iron,copper,aluminum)Nonmetallicminerals(clay,sand,phosphates)1-3 RESOURCESWhat Is a Resource? Things We Need or WantWe obtain resources from the environment to meetour needs and wants.From a human standpoint, a resource is anything obtainedfrom the environment to meet our needs andwants. Examples include food, water, shelter, manufacturedgoods, transportation, communication, andrecreation. On our short human time scale, we classifythe material resources we get from the environmentas perpetual, renewable, or nonrenewable, as shown inFigure 1-6.Some resources, such as solar energy, fresh air,wind, fresh surface water, fertile soil, and wild edibleplants, are directly available for use. Other resources,such as petroleum (oil), iron, groundwater (waterfound underground), and modern crops, are not directlyavailable. They become useful to us only withsome effort and technological ingenuity. For example,petroleum was a mysterious fluid until we learnedhow to find and extract it and refine it into gasoline,heating oil, and other products that we could sell at affordableprices.What Are Perpetual and RenewableResources? Resources That Can LastResources renewed by natural processes are sustainableif we do not use them faster than they arereplenished.Solar energy is called a perpetual resource because ona human time scale it is renewed continuously. It is expectedto last at least 6 billion years as the sun completesits life cycle as a star.On a human time scale, a renewable resource canbe replenished fairly rapidly (from hours to severalFreshairFreshwaterFertilesoilPlants andanimals(biodiversity)Figure 1-6 Natural capital: major types of material resources. Thisscheme is not fixed; renewable resources can become nonrenewableif used for a prolonged period at a faster rate than natural processesrenew them.decades) through natural processes. But this worksonly as long as the resource is not used up faster thanit is replaced. Examples of renewable resources areforests, grasslands, wild animals, fresh water, fresh air,and fertile soil.Renewable resources can be depleted or degraded.The highest rate at which a renewable resource can beused indefinitely without reducing its available supplyis called its sustainable yield.When we exceed a renewable resource’s naturalreplacement rate, the available supply begins to shrink,aprocess known as environmental degradation. Examplesinclude urbanization of productive land, excessivetopsoil erosion, pollution, deforestation (temporaryor permanent removal of large expanses of forestfor agriculture or other uses), groundwater depletion,overgrazing of grasslands by livestock, and reductionin the earth’s forms of wildlife (biodiversity) by eliminationof habitats and species.Case Study: The Tragedy of the Commons—Degrading Free Renewable ResourcesRenewable resources that are freely available to everyonecan be degraded.http://biology.brookscole.com/miller149