Seite - 115 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

5 Attribution:HowIs ItRelevant forLoss… 115 5.1 Introduction The science of attributing observed phenomena to human-induced and natural cli- mate drivers has seen remarkable progress since its emergence in the 1990s. The first studiesdemonstrated that the late20thcentury increase inglobalmeansurface temperaturewouldnothaveoccurredwithouthumaninfluenceonconcentrationsof greenhousegases (GHGs)andaerosols (Tett etal.1999;Stott etal.2000). Insubse- quentyears,manymorestudiesofglobal temperaturesupportedthisfinding, leading togreaterandgreaterconfidenceinanthropogenicinfluenceonglobalwarming(San- teretal.1995;Mitchell et al.2001;Hegerletal.2007;Bindoffetal.2013), and, the most recent reportof the IntergovernmentalPanelonClimateChange(IPCC)states that anthropogenicdrivers are“extremely likely [or>95%probability] tohavebeen the dominant cause of the observed warming since themid-20th century” (IPCC 2014). These scientific attribution statements provide a fundamental underpinning for theUnitedNationsFrameworkConventiononClimateChange (UNFCCC;UN 1992), demonstrating that recent warming was predominantly caused by human emissions of carbon dioxide, methane, and short-lived climate forcings (SLCFs), andmodifications toGHGconcentrations associatedwith landuse change (LUC); and thusestablishing the imperative formitigation. As theUNFCCC’smandate has extendedbeyondmitigation, to include adapta- tion, and nowLoss andDamage (L&D) from climate change impacts (UNFCCC 2013, 2015; see introductory chapter byMechler et al. 2018), new challenges and questionsareemergingabout thescienceofattribution,andits role inpolicy.Whilst there is strong evidence fromattribution studies that human activity is influencing global and regional temperatures (Bindoff et al. 2013), and also other global and regional scale changes (including sea level rise, e.g.Church et al. 2013; and atmo- sphericmoisturecontent, e.g.Santeretal.2007),understandinghowanthropogenic drivers influencelossesanddamagesinparticularecosystems,economies,andcom- munities is averydifferent endeavour,which raisesquestionsextending farbeyond physicalclimatescience.Whenreferring to the lossofcoastline fromastormsurge, fatalities during a heat wave, or famine during a drought, the issue of causality becomesmore challenging scientifically.Aswewill explore in this chapter, at this scaleandcomplexity,multiplefactorscontributetoaspecificlossordamage,andthe signalfromclimatechangeismoredifficulttodetectrelativetothemanyotherpoten- tialinfluencesonhazardoccurrence,exposure,andvulnerability(Huggeletal.2013). Questions about attributionof specific losses anddamages alsomake the impli- cationsof the scientific researchmorepolitical than the implicationsof studies into global or regional climate. Now questions are being asked about the influence of human actions (through anthropogenic GHGs) on specific people, and often not the same people who were responsible for the majority of GHG emissions. It is thereforenotdifficult tounderstandwhy, in thecontextofL&Dpolicydiscussions, attributionhasoftenbeenassociatedwithresponsibility,blame,andliability.Forsci- entists, researchintocausalityisafundamentalroutetowardsunderstandinghowthe EarthSystemworks, andattribution research isnotnecessarily intended to identify responsibleparties.Inthecontextofpoliticalnegotiations,however,evenmentioning attributionsciencecanbeseenas, andarguablyoften is, apoliticalmove.