Environmental Problems, Their Causes, and Sustainability 1

PreventionCut fossil fueluse (especiallycoal)Shift from coalto natural gasImprove energyefficiencyShift torenewableenergy resourcesTransfer energyefficiency andrenewable energytechnologiesto developingcountriesReducedeforestationUse moresustainableagricultureLimit urbansprawlReduce povertySlow populationgrowthSolutionsGlobal WarmingCleanupRemove CO 2from smokestackand vehicleemissionsStore (sequester)CO 2 by plantingtreesSequesterCO 2 deepundergroundSequester CO 2in soil by usingno-till cultivationand taking cropland out ofproductionSequester CO 2in the deep oceanRepair leaky naturalgas pipelines andfacilitiesUse feeds thatreduce CH 4emissions bybelching cowsFigure 21-17 Solutions: methods for slowing atmosphericwarming during this century.smokestacks and store (sequester) it in other parts ofthe environment.One possible way to remove CO 2 from the atmosphereis to plant trees that store (sequester) it in biomass.But studies indicate that this is a temporaryapproach because trees release their stored CO 2 backinto the atmosphere when they die and decompose or ifthey are burned (for example, by forest fires or to clearland for crops).A second approach is soil sequestration in whichplants such as switchgrass are used to remove CO 2from the air and store it in the soil. But warmer temperaturescan increase decomposition in soils and returnsome of the stored CO 2 to the atmosphere.A third strategy is to reduce the release of carbondioxide and nitrous oxide from soil. Ways to do this includeconservation cultivation (Figure 14-13, p. 284) andretiring depleted crop fields, leaving them untouchedas conservation reserves.A fourth approach is to remove CO 2 from smokestacksand pump it deep underground into unminablecoal seams and abandoned oil fields or inject it into thedeep ocean, as shown in Figure 21-18.There are several problems with this strategy.One is that current methods can remove only about30% of the CO 2 from smokestack emissions andwould double or triple the cost of producing electricityby burning coal. The U.S. Department of Energyestimates that the cost of sequestering carbon dioxidein various underground and deep ocean repositorieswill have to be reduced at least 10-fold to make thisapproach economically feasible. In addition, injectinglarge quantities of CO 2 into the ocean could upset theglobal carbon cycle, seawater acidity, and some formsof deep-sea life in unpredictable ways.Some scientists have suggested that we add iron tothe oceans (especially in Antarctic waters) to stimulatethe growth of marine algae, which could remove moreCO 2 through photosynthesis. But the algae would returnit to the atmosphere a short time later when theydied unless the carbon is somehow deposited in thedeep ocean. Furthermore, we do not know the potentialeffects of applying large amounts of iron to theocean’s ecosystems.How Can Governments Reduce the Threatof Global Warming? Use Sticks and CarrotsGovernments can tax greenhouse gas emissionsand energy use, increase subsidies and tax breaksfor saving energy and using renewable energy,and decrease subsidies and tax breaks for fossilfuels.Governments could use three major methods to promotethe solutions to slowing global warming listed inFigure 21-17. One is to phase in output-based carbontaxes on each unit of CO 2 emitted by fossil fuels (especiallycoal and gasoline) or input-based energy taxes oneach unit of fossil fuel (especially coal and gasoline)that is burned. Decreasing taxes on income, labor, andprofits to offset increases in consumption taxes oncarbon emissions or fossil fuel use could help makesuch a strategy more politically acceptable.A second strategy is to level the economic playingfield by greatly increasing government subsidies forenergy-efficiency and carbon-free renewable-energytechnologies, carbon sequestration, and more sustainableagriculture, and by phasing out subsidies and taxbreaks for using fossil fuels.The third strategy is technology transfer. Governmentsof developed countries could fund the transferof energy-efficiency, carbon-free renewable-energy,http://biology.brookscole.com/miller14479