The 21st Century climate challenge

latter figure represents around 2 percentof global emissions. However, because theemissions are released directly into thehigh atmosphere, the radiative forcingeffects are far stronger, accounting for3 percent (2–8 percent range) of globalwarming. 18 For several OECD countries,aviation represents a significant andgrowing share of the national contributionto global warming. In the UnitedKingdom, annual emissions from aviationare projected to grow by between 62 and 161Mt CO 2by 2050. In order to offset emissionsfrom the aviation sector and achieve thenational target of a 60 percent reductionin overall emissions by 2050, other sectorswould have to reduce their emissions by71–87 percent. 19 This is not a plausibleoption, suggesting that aviation will haveto be subject to cuts in emissions.• Insufficient urgency. Sometimes decisions inpublic policy can be postponed without greatcost. That is not the case with climate change.Because emissions are long-lived, delaying thedecision to reduce them adds to the stock ofgreenhouse gases and cuts the time frame forreducing it. Several legislative proposals forthe United States envisage limited cuts to2020 against 1990 levels, followed by steeperdeclines thereafter. That approach may beill-advised. One study for the United Statesshows that a pathway for contributing to aglobal stabilization level at 450 ppm CO 2ecan be achieved with annualized reductionsof 3 percent a year by 2050. However, delayingaction until 2020 would require reductionsof 8.2 percent a year—which would requirestringent adjustments and an implausiblerate of technological innovation. 20is instructive. In Canada, energy-intensive economicgrowth has comprehensively underminedthe prospects for delivery against the country’sKyoto commitments (box 3.2). Unlike Canada,the United Kingdom is on-track to meet itsKyoto targets, though not primarily as a resultof energy policy reform: a shift in energy mixfrom coal to natural gas has been more important.The country has now defined an ambitiouscarbon budget that sets a pathway for reducedemissions through to 2050. However, CO 2emissions from the United Kingdom have notfallen over the past decade—and there are seriousquestions over whether or not the countrywill achieve national targets for reduced emissions(box 3.3).Institutional arrangements play an importantrole in determining the credibility ofemissions reduction targets. In carbon budgeting,as in financial budgeting, governance mattersa great deal, not least in ensuring that targetsare translated into outcomes. This is anotherarea in which California has provided leader-Figure 3.1Change 1990–2004 (%)–50Falling carbon intensity doesnot always lower emissionsIntensity (CO 2emissions per unit of GDP PPP US$)CO 2emissions050CanadaFranceGermanyItalyExperience under theKyoto Protocol provides aconstant reminder of thelimited progress made inaligning climate securitygoals with energy policies3Avoiding dangerous climate change: strategies for mitigationTargets matter, but so do outcomesSetting targets is not the same as deliveringresults. Experience under the Kyoto Protocolprovides a constant reminder of the limitedprogress made in aligning climate security goalswith energy policies.The experience of two countries at differentends of the Kyoto Protocol performance leagueSource: Indicator Table 24.JapanRussianFederationUnitedKingdomUnitedStatesHUMAN DEVELOPMENT REPORT 2007/2008 119