北极熊陷绝境：悲剧不仅是自相残杀Polarbearsstraits:thetragedyisnotonlykilleachother饥肠辘辘的北极熊不得已同类相食.Starvingpolarbearsturntocannibalism.最近拍摄到的照片显示,由于全球变暖导致猎食地消失,北极熊开始捕食同类.Newpicturesshowthatpolarbearsarebeginningtocannibaliseeachotherasglobalwarmingdestroysitshuntinggrounds.北极熊通常在浮冰上抓捕海豹作为食物.但由于全球变暖,浮冰融化,在海上猎食也越来越困难,北极熊的捕猎场所也不得不转移到陆地上.Polarbearsusuallysubsistonseals,whichtheyhuntfromaplatformofseaice.Butthemeltingofseaiceasaresultofrisingglobaltemperatureshasmadeitmoredifficultforpolarbearstohuntsealsatsea,confiningthebearstoland.有更多的北极熊淹死在海里,因为它们被迫游向更远的海域去寻找食物.Drowningisalsomorecommonasbearsareforcedtoswimfurtherouttoseatofindfood.这些照片进一步证实了越来越多处于绝境之中的北极熊,为了生存,开始捕杀自己的同伴.科学家们称本年度内已经发生八起这样的事件.Theimagesaddtotheevidencethatpolarbearsareincreasinglyhuntingeachotherforfoodintheirdesperationtosurvive.Scientistssaytheyareawareofeightcasessofarthisyear.美国地质调查局和世界自然保护联盟近日分析指出,在接下来的五十年内,由于全球变暖,极地浮冰融化,世界上仅存的20000到25000只北极熊还将减少三分之二.RecentanalysisbytheUSGeologicalSurveyandWorldConservationUnionfoundthattwo-thirdsofthe20,000to25,000polarbearsintheworldcouldbelostinthenext50yearsaswarmingtemperaturesmelttheice.失去浮冰栖息地,北极熊将无法长期生存下去.其他威胁,包括原油和天然气钻探、海运及有毒物质污染,与气候剧变和浮冰融化相比都不值一提.Withouttheseaicehabitat,thepolarbearwillnotsurviveinthelongterm.Thereareotherthreats,suchasoilandgasdrilling,shippingandtoxins,buttheypaleincomparisontoclimatechangeandthelossoftheseaice.