Seite - 348 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

348 A.MarkandyaandM.González-Eguino Fig.14.2 Temperaturepathways for lowandhighdamagescenarios future, specifies the level that future additions towelfare are reduced—a standard procedure in economics, howeverwith heateddebate as to the level of discounting (see furtherbelow). Figure 14.2 shows the temperature pathways for four scenarios: (i) low dam- age/low emissions with a low discount rate (LDAM-LDR), (ii) low damage/low emissions with a high discount rate (LDAM-HDR), (iii) high damage/high emis- sionswitha lowdiscount rate (HDAM-LDR),and(iv)highdamage/highemissions withahighdiscountrate(HDAM-HDR).Thehighdiscountratecaseistheonewhere the rate is set initially at 3%and then declines over time as in the IAMsWITCH, DICEandRICE(seeNordhausandBoyer2000).Thelowdiscountrate iscaseis the onewhere the rate is set as 0.1%and thendeclines as inStern (2007).Tokeep the analysissimpleweconsideronlyversions(ii)and(iii)of theiranalysisandusethem tocalculate residualdamagesover time.Thisprovidesabroad rangeofestimates. For thesecasesBoselloetal. (2010)developedaversionof theWITCHmodel to predict total damages.Themodel developedbyBosello et al. has 12world regions (see regions furtherbelowinTables14.1and14.2).Themodel is run toobtain time profiles to 2100 for total global damages and expenditures on adaptation.Residual damages areonlygivenglobally, and in themodel the regional share is assumed to beproportional totheregionalshareofdamages.Inordertoobtainresidualdamages by regionwe takefigures of total damages by region,which are reported for three IAMs:NordhausandBoyer(2000),AD-WITCHandtheBoselloetal. (2010)model fortheentireperiod.Theaverageshareofthesetotaldamagesbyregioniscalculated and then applied to the total residual damages by time period as given inBosello et al. to obtain residual damages by region and time period for each scenario (all