emissionsletitbe歌词

923LetitsnowGlobalsnowcoveragehasdeclinedsubstantiallywithanthropogenicwarming,impactingbiological,socio-economicandphysicalsystems.
ThisissueincludesasuiteofComments,Reviews,Perspectivesandoriginalresearchdocumentingtheimportanceofsnowintheclimatesystem,andhowthismaychangewithcontinuedwarming.
AsGameofThronescharacterJonSnowforewarns,"Winteriscoming",andformany(includingthoseinthefictitiouslandofWesteros)thismeanssnow.
Imagesofsnowballfights,snowmen,skiingandthefestiveseason(atleastintheNorthernHemisphere)aresynonymouswithwinter.
ButsnowisfarmoreimportantthanprovidingopportunitiesforwinterrecreationorGameofThronesmemes.
Snowisakeycomponentoftheglobalclimatesystem,influencingsurfaceenergybudgets,regulatingtemperatures,drivingatmosphericteleconnectionsandgoverninghydrologicalsystems.
Asweexploreinthisissueandinanaccompanyingonlinecollection—www.
nature.
com/collections/snow—theroleofsnowisbeingimpactedbyanthropogenicclimatechange,withpotentiallysevereimplications.
Snowiscreatedwhensufficientlymoistairisexposedtotemperaturesbelow2°C,formingicecrystalsthatagglomerateandfallundertheirownweight.
Therefore,withwarmertemperatures,ithaslongbeenrecognizedthatglobalsnowcoverwilldecline.
Naturally,warmingpreventssnowformation(causingittoinsteadfallasrain)andacceleratesthemeltofexistingsnowpacks1.
Surfacedarkeningassociatedwithlight-absorbingparticles(suchasdustandblackcarbon)isfurtherknowntohavedrivencontemporarymeltofthecryosphereviaperturbationstosurfacealbedo.
IntheirReviewinthisissue,McKenzieSkilesandco-workerssuggestthiseffectmaybeenhancedinthefutureduetogreaterdustdepositionassociatedwitharidification,aswellasincreasingblackcarbonemissionsinindustrializingnations.
AsreportedbyKatBormannandcolleagues,snowcoverageisnowonemonthshorteracrosslargeswathesoftheNorthernHemispherecomparedto40yearsago.
Wherefeedbackpotentialisstrongest,thesechangesaremostnotable,includingacrossEurasia.
Synthesizing30yearsofresearch,GinaHendersonandco-authorsillustratethatsnowvariabilityinthisregioncanforceshiftsintheNorthAtlanticOscillation(orNorthernAnnularMode),perturbingtheatmosphericcirculation,andthereforetemperatureandprecipitationpatterns,acrossmuchoftheNorthernHemisphere.
EurasiansnowcoveralsoplaysastrongroleindeterminingthetimingandstrengthoftheAsiansummermonsoons2,whichmillionsrelyonforfreshwater.
Snow–atmospherecouplingthereforehasthepotentialtoextendtheclimaticimpactsofsnowvariabilityfarbeyondtheregionsofanomaloussnow.
Changesinsnowcover,however,arenotconfinedtosuchcontinentalscales.
AsBormannetal.
document,markedsnowlosshasalsobeenobservedinseveralmountainlocationssuchastheSierraNevadaandHighMountainAsia,wheremeltisintegralforsociety.
ASnapshotinthisissue,forexample,emphasizeshowchangingsnowmeltcharacteristics—earliermeltanddecreasedflow3—imperilwatersecurityinheavilypopulatedregionsincludingthewesternUnitedStates,IndiaandChina.
Suchshiftsinsnowmeltfurtherthreatenhydropowerproduction,akeyenergysourceintheselocations.
Althoughshiftsinsnowmayhavebroaderconsequencesbeyondtheregionsofdirectsnowcover,theireffectscanalsobemorelocal.
Inmountainregions,forexample,snowsupportseconomiesthroughwintertourismandrecreation.
Withdeterioratingsnowconditions,itisclearthatsnowtourismhasbegun,andwillcontinue,tosuffer:mostglobalskiresortsreportshorterskiseasons,increasedartificialsnow-makingandlowertouristnumbers4.
Indeed,skiresortsfromtheUnitedStates5toAustralia6areprojectedtobecomelesseconomicallyviableinthenearfuture.
Inaddition,theseresortsmayfacefurtherrisksfromavalanches,aswarmertemperaturesandincreasedrain-on-snoweventsacttodestabilizethesnowpack(seetheFeaturebyOliveHeffernaninthisissue).
Snowisalsoanimportantdeterminantofbiologicalcommunitiesandecosystemfunction7,actingasaprotectiveinsulatinglayeragainstextremeatmosphericcold,arefugeforhibernationandacontrolonplantphenology.
Anychangeinsnowcharacteristicsinfluencesthesefunctions.
Forexample,increasesinrain-on-snoweventsraisethelikelihoodofice-layersforminginthesnowpack,threateningplants,herbivores(suchaslemmingsandreindeer)andtheircorrespondingpredators8.
Inthisissue,PekkaNiittynenandcolleaguesfurtherdemonstratethatreductionsinsnow-coverdurationaccelerateratesoflocalmoss,lichenandvascularplantextinctioninFennoscandia.
Thechangingnatureofsnowunderanthropogenicwarming—includingcoverage,durationandmeltcharacteristics—standstoexertsubstantialimpactsacrossphysical,biologicalandsocio-economicsystems.
However,ourunderstandingoftheseimpactsisoftenconstrainedbyinadequatesnowobservations,limitedinbothspatialandtemporalresolution.
Indeed,acommonthemeacrossmanypiecesinthissnowissueistheneedforfurtherobservations,beittoconstrainmodels,validateremotesensingproductsorquantifycurrentsnowmeltrates.
AssuggestedinaSnapshot,citizenscienceprojectsmayoffersomehopeforincreasingthenumberoffieldmeasurements.
Nevertheless,itisclearthatfurthereffortsareneededtoadapttopresent-dayandprojecteddeclinesinsnowcover.
Publishedonline:29October2018https://doi.
org/10.
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com/natureclimatechange