UnitedNationsFrameworkConventiononClimateChange"(UNFCCC)inthefirstparagraph,thewords"climatechange"isdefinedas:"Afteraconsiderableperiodoftimeofobservation,inadditiontonaturalclimatechangebyhumanactivities,eitherdirectlyorindirectlycausedbychangesinglobalatmosphericcompositionofclimatechange."UNFCCCwillthereforebearesultofhumanactivitieschangetheatmosphericcompositionofthe"climatechange"andattributedtonaturalcauses"climatevariability"todistinguish.Climatechange(climatechange)aremainlymanifestedinthreeareas:globalwarming(GlobalWarming),acidrain(AcidDepostion),ozonedepletion(OzoneDepletion),inwhichglobalwarmingismankind'smostpressingproblemsrelatedtohumanFuture!

　　Causedbyclimatechange,whatarethereasons?

　　Climatechangemaybeduetonaturalinternalprocessesorexternalforcing,orartificiallysustainedcomponentsoftheatmosphereandland-usechange.Bothnaturalfactors,butalsosomeofthefactors.Intheman-madefactors,mainlyduetohumanactivitiessincetheIndustrialRevolution,especiallytheprocessofindustrializationindevelopedcountriescausedbyeconomicactivities.Fossilfuelburninganddeforestation,land-usechange,greenhousegasemissionsfromhumanactivitiesledtoasubstantialincreaseinatmosphericgreenhousegasconcentrations,enhancethegreenhouseeffect,causingglobalwarming.AccordingtotheU.S.OakRidgelaboratorystudiesreportthatsince1750,globalcumulativeemissionsofmorethan1trilliontonsofcarbondioxideemissionsindevelopedcountrieswhichaccountforabout80%.Whataretheimplicationsofclimatechangewillbring?Climatechange,leadingtofrequentcatastrophicweatherevents,acceleratedmeltingofglaciersandsnowcover,waterdistributionimbalances,biodiversityisunderthreat.Climatechangeisalsocausedbysea-levelrise,coastalareassubjecttofloods,stormsandothernaturaldisastersisevenmoreserious,smallislandstatesandlow-lyingcoastalareasevenfacingthethreatofbeingsubmerged.Ofclimatechangeonagriculture,forestry,animalhusbandry,fisheryandothereconomicandsocialactivitieswillhaveanegativeimpact,exacerbatingthespreadofdisease,threateningthesocio-economicdevelopmentandpeople'shealth.AccordingtotheIntergovernmentalPanelonClimateChangereport,iftemperaturesrisebymorethan2.5℃,allregionsarevulnerabletotheadverseeffectsofthelosssufferedparticularlysevereindevelopingcountries;iftemperature4℃,theglobalecosystemmaynotcauseanyirreversibledamage,causingheavylossestotheglobaleconomy.AccordingtoChinain2006"issuedbyNationalAssessmentReportonClimateChange,"theimpactofclimatechangeonChina'sfocusonagriculture,waterresources,naturalecosystemsandcoastalzones,etc.,mayleadtoincreasedinstabilityinagriculturalproduction,floodingthesouthernregionheavierthenorthintensifiedconflictsbetweenwatersupplyanddemand,forestandgrasslandecosystems,suchasdegradation,biologicaldisastershair,reductionofbiodiversity,frequenttyphoonsandstormsurges,coastalzonedisasterintensifiedonmajorprojectconstructionandoperationofsecurityhasbeenaffected.