The 21st Century climate challenge

3Avoiding dangerous climate change: strategies for mitigationThe regulatory environmentfor transport is a criticalpart of the internationalcarbon mitigation effortof CO 2emissions. In 2004, the transport sectorproduced 6.3 Gt CO 2. While the share ofdeveloping countries is rising, OECD countriesaccount for two-thirds of the total. 82 Theautomobile sector in these countries accountsfor about 30 percent of total greenhouse gasemissions, and the share is rising over time. 83The regulatory environment for transportis a critical part of the international carbonmitigation effort. Aggregate greenhouse gasemissions from any vehicle is a function of threefactors: miles travelled, amount of fuel used foreach mile travelled, and the carbon content ofthe fuel. Emissions are rising in many countriesbecause the distances travelled are growingfaster than fuel-use efficiency, and because fueleconomy gains have been reduced by a trendtowards bigger and more powerful vehicles.Setting the standardCountries vary widely in their fuel efficiencystandards. The European Union and Japan havethe highest standards, while the United Stateshas the lowest in the developed world—lower,in fact, than in China (figure 3.5). 84Efficiency standards in the United Statesrelative to the rest of the world have slippedover time. One reason for this is that they havechanged only marginally over the past two decades,whereas other countries have been settinghigher standards. Another is the prevalence ofregulatory gaps favouring low-efficiency sportsutility vehicles.These gaps have reduced fleet efficiency anddriven up emissions. Since 1990, emissions fromtransport have increased at an annual averagerate of 1.8 percent, almost double the rate for allother sources. The primary driver of the emissionsupsurge is vehicle miles travelled (whichhas climbed by 34 percent) and an increase inthe use of light-duty trucks (box 3.8). 85Improvements in United States regulatorystandards could make a global difference in climatechange mitigation, with large associatedbenefits for national energy security. Accordingto the National Commission for Energy,increasing the fuel efficiency requirement forcars in the United States by 20 miles per gallon(equivalent to 8.5 kilometres per litre) wouldreduce projected oil consumption by 3.5 millionbarrels a day, diminishing CO 2emissionsby 400 million tonnes per year in the process. 86The savings from that regulatory shift wouldbe equivalent to France’s total CO 2emissions.Apart from the benefits for climate change mitigation,the associated reduction in oil importswould achieve one of the central goals of UnitedStates energy security policy.While the European Union has attainedrelatively higher fuel efficiency than the UnitedStates, it faces problems in aligning standardswith its stated climate change goals. Since 1990,Figure 3.5Rich country fuel efficiency standards vary widelyMiles per gallon a555045JapanEU403530ChinaAustraliaCanadaCalifornia2520US2002 2004 2006 2008 2010 2012 2014 2016a. Recalculated to comply with Corporate Average Fuel Economy (CAFE) test cycle as used in the United States.Source: NREL Energy Analysis Office 2005b.138 HUMAN DEVELOPMENT REPORT 2007/2008