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1、Unit6EarthfirstStep1诵读经典·渗透文化意识Ⅰ.细品味经典文章(2019·北京高考)Bytheendofthecentury,ifnotsooner,theworld’soceanswillbebluerandgreenerthankstoawarmingclimate,accordingtoanewstudy.Attheheartofthephenomenonlietinymarinemicroorganisms(海洋微生物)calledphytoplankton.Becauseofthewaylightreflec
2、tsofftheorganisms,thesephytoplanktoncreatecolourfulpatternsattheoceansurface.Oceancolourvariesfromgreentoblue,dependingonthetypeandconcentrationofphytoplankton.Climatechangewillfuelthegrowthofphytoplanktoninsomeareas,whilereducingitinotherspots,leadingtochangesintheocean
3、’sappearance.Phytoplanktonliveattheoceansurface,wheretheypullcarbondioxide(二氧化碳)intotheoceanwhilegivingoffoxygen.Whentheseorganismsdie,theyburycarboninthedeepocean,animportantprocessthathelpstoregulatetheglobalclimate.Butphytoplanktonarevulnerabletotheocean’swarmingtrend
4、.Warmingchangeskeycharacteristicsoftheoceanandcanaffectphytoplanktongrowth,sincetheyneednotonlysunlightandcarbondioxidetogrow,butalsonutrients.StephanieDutkiewicz,ascientistinMIT’sCenterforGlobalChangeScience,builtaclimatemodelthatprojectschangestotheoceansthroughoutthec
5、entury.Inaworldthatwarmsupby3℃,itfoundthatmultiplechangestothecolouroftheoceanswouldoccur.Themodelprojectsthatcurrentlyblueareaswithlittlephytoplanktoncouldbecomeevenbluer.Butinsomewaters,suchasthoseoftheArctic,awarmingwillmakeconditionsriperforphytoplankton,andthesearea
6、swillturngreener.“Notonlyarethequantitiesofphytoplanktonintheoceanchanging,”shesaid,“butthetypeofphytoplanktonischanging.”Andwhydoesthatmatter?Phytoplanktonarethebaseofthefoodweb.Ifcertainkindsbegintodisappearfromtheocean,Dutkiewiczsaid,“itwillchangethetypeoffishthatwill
7、beabletosurvive.”Thosekindsofchangescouldaffectthefoodchain.Whatevercolourchangestheoceanexperiencesinthecomingdecadeswillprobablybetoogradualandunnoticeable,buttheycouldmeansignificantchanges.“It’llbeawhilebeforewecanstatisticallyshowthatthechangesarehappeningbecauseofc
8、limatechange,”Dutkiewiczsaid,“butthechangeinthecolouroftheoceanwillbeoneoftheearlywarningsignalsthatwer
