两极冰川融化 英文.ppt.ppt

polaricecapmelting,polaricecap,polaricecapmelting,effects,causes,solutions,howdotheyform?,athigherlatitudes,theearthdoesntreceivemuchsunlightand,thereforethetemperaturesremainlowformostpartoftheyear,thusthewatercantremaininliquidformanditsolidifiesi.e.turnsintoice.incaseofourownplanet:thenorthernandthesouthernpolesarewheretheicecapsarelocated.,earthsnorthpoleiscoveredbyfloatingpackice(seaice)overthearcticocean.portionsoftheicethatdontmeltseasonallycangetverythick,upto34metersthickoverlargeareas,withridgesupto20metersthick.one-yeariceisusuallyaboutameterthick.theareacoveredbyseaicerangesbetween9and12millionkm.thelandmassoftheearthssouthpole,inantarctica,iscoveredbytheantarcticicesheet.itcoversanareaofabout14.6millionkmandcontains25-30millionkmofice.around70%ofthefreshwaterontheearthisheldinthisicesheet.,theiceismeltingbybanki-moonpublished:september17,2009newyorktimestwoweeksago,ivisitedthearctic.isawtheremainsofaglacierthatjustafewyearsagowasamajestic(宏伟的)massofice.ithadcollapsed.notslowlymeltedcollapsed.itraveledninehoursbyshipfromtheworldsnorthernmostsettlementtoreachthepolaricerim.injustafewyears,thesameshipmaybeabletosailunimpeded（畅通无阻的）allthewaytothenorthpole.thearcticcouldbevirtuallyice-freeby2030.,iwasalarmedbytherapidpaceofchangethere.worsestill,changesinthearcticarenowacceleratingglobalwarming.thawingpermafrostisreleasingmethane,agreenhousegas20timesmorepowerfulthancarbondioxide.meltingiceingreenlandthreatenstoraisesealevels.,causes,geologicalchangesseasonalchangesglobalwarming,geologicalchanges,thecausesforthesechangescanbeexplainedbymilankovitchcycles.thecyclesproposedbyhimtakeintoaccountorbitalshapes(eccentricity偏心率),axialtilt轴倾角(obliquity倾角),axialprecession岁差,apsidalprecessionandorbitalinclination倾角.allthesefactors,whencombined,affecttheconditionsontheplanetinthelongtermanditcausesiceagesatdifferenttimes.duringaniceagetheicecapsincreaseinsizeandtheyretreatwhenaniceageends.thesechangesoccuroveraperiodrangingfromthousandstomillionsofyears.,seasonalchanges,theyaremedium-termchangesandtheyoccureveryyear.everyyearwiththecomingofthewinterseason,theicecapsbegintoexpandbuttheymeltagainwiththecomingofthesummerseasons.,globalwarming,therearemanycausesofthemeltingofthepolaricecapsandglobalwarming,someofwhicharenatural.however,theactivitiesofmanareresponsibleformuchoftherapidchangethatscientistsareseeing.humankindengagesinamultitudeofactivitiesthathaveacceleratedtheprocessofglobalwarming.,mostpeopleknowthattheman-madeactivitythathasbeencitedasamajoracceleratorofglobalwarmingisthecombustionoffossilfuels,suchascoalandpetroleum.industrialprocessesandtheoperationofpersonalmotorvehiclesallreleasevariousemissionsintotheair,includingcarbonmonoxide一氧化碳,hydrocarbons碳氢化合物,andlead铅,whichturntocarbondioxide.miningactivitiesalsoreleasemethane甲烷intotheatmosphere,whichisagreenhousegasthatleadstoawarmingplanet.,theoverpopulationoftheplanetisanotheractivitythathasacceleratedglobalwarming.morepeopleontheplanetmeanstherearegreaterenergyrequirements,moretransportationandincreasedneedforfood.becauseoftheneedforcheapgoodsduetotheamountofpeopleontheplanet,plasticgoodshavebeenconstructed,whicharenotbiodegradable.,morepeoplealsomeansmorecarsandmorecarbonemissionsmovingintotheair.themorepeoplethereare,themoreroomneedstobemadefortheworldspopulation,whichleadstoexpansionintowild,naturalareas,likeforests,whichprotecttheplanetsdelicatebalance.,oneoftheleastwell-knowncausesofglobalwarmingisdeforestation.becauseofmanscravingforspace,lumber,andbeef,manyoftheplanetsforestshavebeendestroyed.treeshavebeencutdowntobeusedforconstruction,inordertoclearroomfornewdevelopmentsorhouses,andtomakeroomforcattletograzeinordertosatisfythedemandforbeef,especiallyintheunitedstates.,however,theforestsaroundtheplanethaveaprotectivepurpose,becausetheyproduceoxygenthatreducestheamountofcarbondioxideintheatmosphere.whenforestsareslashedandburned,carbonemissionsskyrocket猛涨.boththeactofburningtheseorganicmaterialsandthelossofthetreesspeedupglobalwarming.,effectsofmelting,thearcticcouldseeice-freesummersbytheendofthe21stcenturyifthecurrentrateoficecapshrinkingcontinues,accordingtothenaturalresourcesdefensecouncil(nrdc).thelargestblockoficeinthearcticisbreakingintopieces,andthesummerpolaricecaphasshrunksome20percentsince1979.meltingicecapsaffectlocalresidentsandwildlife,andcouldhaveafar-reachingimpactworldwidethroughrisingsealevelsandglobaltemperatures,climate,researchcarriedoutbyscientistsatnasa美国国家航空航天局showsthatmeltingicecapshaveaneffectontheearthsclimate.thepolaricecapsthatcoverthetopandbottomoftheearthreflectsunlightintospace.whentheicecapsrecededuetomelting,thesunlightisabsorbedbytheoceanandlandinsteadofbeingreflectedbacktospace.asaresult,theplanetbecomeswarmer,moreicemeltsandthecyclerepeatsitself.,theenvironmentalprotectionagency(epa)citesastudyonitswebsiteproducedbythearcticcouncilwhichstatesthatinrecentdecadestheaveragetemperatureinthearctichasrisenatnearlydoubletherateoftemperatureselsewhereintheworld.thiswarmingisevidencedbymeltingofglaciersandseaice,whichaffectstheclimatesystemthroughsuchphenomenaasincreasedacidityintheoceanandanuptakeingreenhousegases.,oceans,thenrdc美国自然资源保护委员会notesonitswebsitethatthemeltingarcticicecapscouldhaveanimpactontheearthssealevels.asicesheetsandglaciersmelt,oceansaroundtheworldrise.theserisingsealevelsresultinfreshwatercontamination,floodingandbeacherosion.risingsealevelscouldhaveadevastatingimpactonislandnationsandcities,suchasthemaldivesorshanghaithatareatornearsealevel.intheu.s.,a3-footlevelsearise-whichcouldoccurbytheyear2100-wouldresultintheinundation洪水ofmorethan22,000squaremilesoflandalongthegulfcoast.墨西哥湾岸区,ecosystems,themeltingpolaricecapshaveawide-rangingimpactonecosystems.migratoryanimalspeciesthatdependonthearcticasaplacetofeedandreproducearenegativelyaffectedbyalossofseaice.speciesthatarenativetothearctic,suchaspolarbearsandseals,areparticularlyhardhitbyseaicereduction.,asicedisappears,treesthatgrowintheirplacewouldabsorbsunlightandcontributetothewarminginthearea,accordingtotheepa环境保护局.peoplelivinginthearcticregionmayseebuildingsandworkplacesdestabilizedduetothethawingoffrozenground.alongcoastlines,villagesareindangerofbeingflooded.,advicesfrombanki-moon,first,everycountrymustdoitsutmosttoreduceemissionsfromallmajorsources.industrializedcountrieshavetostrengthentheirmitigation减轻targets,whicharecurrentlynowhereclosetowhattheipcc政府间气候变化专门委员会saysisneeded.developingcountries,too,mustslowtheriseintheiremissionsandaccelerategreengrowthaspartoftheirstrategiestoreducepoverty.,second,asuccessfuldealmusthelpthemostvulnerabletoadapttotheinevitableimpactsofclimatechange.thisisanethicalimperativeaswellasasmartinvestmentinamorestable,secureworld.,third,developingcountriesneedfundingandtechnologysotheycanmovemorequicklytowardlow-emissionsgrowth.adealmustalsounlockprivateinvestment,includingthroughcarbonmarkets.,fourth,resourcesmustbeequitablymanagedanddeployedinawaythatallcountrieshaveavoice.,advicesforindividuals,therearemanysimplethingsyoucandoinyourdailylifewhatyoueat,whatyoudrive,howyoubuildyourhomethatcanhaveaneffectonyourimmediatesurrounding,andonplacesasfarawayasafrica.hereisalistoffewthingsthatyoucandotomakeadifference:,adjustyourthermostatrmsttn.自动调温器,温度调节装置userecycledpaperusecompactfluorescentflresntadj.萤光的bulbstakeshortershowersinstallalow-flowshowerheadbuymin