The 21st Century climate challenge

3Avoiding dangerous climate change: strategies for mitigationMany of the targets set are,at best, only weakly relatedto sustainable carbonbudget requirementsThe Electric Power Supply Association alsoannounced its support for “comprehensive,mandatory federal legislation to minimize theimpact of greenhouse gases”. 15Four targeting problems incarbon budgetingIs the new trend towards target setting in developedcountries providing a foundation forcarbon budgets that will enable the world toavoid dangerous climate change?The answer to that question is a qualified‘no’. While the adoption of targets is anencouraging indication that public concern isregistering on the political radar screen, manyof the targets set are, at best, only weakly relatedto sustainable carbon budget requirements.Insufficient ambition is a common problem.Another is the confusion associated with aproliferation of targets, especially when thosetargets are inadequately reflected in energypolicies. There are four broad potential sourcesof error in carbon budget targeting that needto be addressed:• Insufficient ambition. Our sustainableemissions pathway establishes twoplausible benchmarks for assessingwhere emissions ceilings need to beset by developed countries. The broadtrajectory: peaking in the period 2012to 2015, cuts of 30 percent by 2020and cuts of at least 80 percent by 2050,against a 1990 baseline. There are twoproblems. First, some targets—the UnitedKingdom’s and several proposals in theUnited States are examples—fall short ofthese benchmarks (table 3.1). Second, theselection of reference years can obscureunder-ambition in target setting. Forexample, some governments interpret thecommitment made at the G8 to “seriouslyconsider” halving emissions by 2050 as animplied reduction from ‘current’ levels.Simple carbon arithmetic demonstrateswhy changes in reference years matters.Shifting the United States reference yearfrom 1990 to 2004, for example, wouldincrease the permitted emissions base byover 900 Mt CO 2e—roughly equivalentto total German emissions in 2004. 16 ForCanada, the same shift in reference yearswould raise the baseline for emissionsby 27 percent over 1990 levels. From acarbon budgeting perspective, any changein base year should include adjustments inreduction targets to compensate for anyincrease in emissions from 1990.• Inaccurate indicators. Some governmentspresent targets for reduced carbon intensityas equivalent to climate change mitigationgoals. This confuses means and ends.Reducing the amount of CO 2emitted forevery dollar in wealth created (the carbonintensity of growth), or for every unit ofpower generated (the carbon intensity ofenergy), is an important goal. No mitigationstrategy is likely to succeed withoutprogress in these areas. However, whatultimately matters is the 'overall reduction'in emissions. From a sustainable carbonbudget perspective, carbon intensity targetsin isolation are a mitigation red-herring.Many countries have an impressive recordin cutting carbon intensity but still havean overall increase in emissions (figure 3.1).The United States has reduced greenhousegas intensity by around 25 percent since1990 but its overall emissions have goneup by an equivalent amount. The GCCItargets a further reduction in greenhousegas intensity of 18 percent between 2002and 2012—broadly consistent with thetrend since 1980. However, the EnergyInformation Administration projects anincrease in CO 2emissions over the sameperiod of around 25 percent. 17• Inadequate sectoral coverage. Effectivecarbon accounting requires that all emissionsare reflected in the budget. Unfortunately,current reporting systems keep somesectors ‘off-budget’. For example, aviationis excluded from international inventoriesof greenhouse gases for the Kyoto Protocol.The Earth’s atmosphere is less discriminating.Since 1990, emissions of CO 2fromaviation fuel have increased from 331Mt CO 2annually to 480 Mt CO 2. The118 HUMAN DEVELOPMENT REPORT 2007/2008