The 21st Century climate challenge

1 The 21 st Century climate challenge Figure 1.4CO 2from Mozambique is the same weight asa tonne of CO 2from the United States.While each tonne of carbon dioxide carriesequal weight, the global account masks largevariations in contributions to overall emissionsfrom different sources. All activities, allcountries and all people register in the globalcarbon account—but some register far moreheavily than others. In this section we look atthe carbon footprint left by emissions of CO 2.Differences in the depth of carbon footprintscan help to identify important issues of equityand distribution in approaches to mitigationand adaptation.Rich countries dominate the cumulative emissions accountShare of global CO 2emissions, 1840–2004 (%)302520151050UnitedStatesRussian China Germany UnitedFederation a KingdomJapan France India Canada Polanda. Includes a share of USSR emissions proportional to the Russian Federation’s current share of CIS emissions.Source: CDIAC 2007.National and regional footprints—the limits to convergenceMost human activities—fossil fuelcombustion for power generation, transport,land-use changes and industrial processes—generate emissions of greenhouse gases. Thatis one of the reasons why mitigation poses suchdaunting challenges.The breakdown of the distribution ofgreenhouse gas emissions underlines the scopeof the problem (figure 1.3). In 2000, just overhalf of all emissions came from the burningof fossil fuels. Power generation accounted foraround 10 Gt CO 2e, or around one-quarter ofthe total. Transport is the second largest sourceof energy-related CO 2e emissions. Over the pastthree decades, energy supply and transport haveincreased their greenhouse gas emissions by145 and 120 percent respectively. The criticalrole of the power sector in global emissions isnot fully captured by its current share. Powergeneration is dominated by capital-intensiveinfrastructural investments. Those investmentscreate assets that have a long lifetime: powerplants opening today will still be emitting CO 2in50 years time.Land-use change also plays an importantrole. Deforestation is by far the largest sourceof CO 2emissions in this context, releasingsequestered carbon into the atmosphere as a40 HUMAN DEVELOPMENT REPORT 2007/2008