IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change

Emission trends

With total 2005 emissions of approximately 1300 MtCO2-eq/yr, the waste sector contributes about 2–3% of total GHG emissions from Annex I and EIT countries and 4–5% from non-Annex I countries (see Table TS.13). For 2005–2020, business-as-usual (BAU) projections indicate that landfill CH4 will remain the largest source at 55–60% of the total. Landfill CH4 emissions are stabilizing and decreasing in many developed countries as a result of increased landfill gas recovery combined with waste diversion from landfills through recycling, waste minimization and alternative thermal and biological waste management strategies. However, landfill CH4 emissions are increasing in developing countries because of larger quantities of municipal solid waste from rising urban populations, increasing economic development and, to some extent, the replacement of open burning and dumping by engineered landfills. Without additional measures, a 50% increase in landfill CH4 emissions from 2005 to 2020 is projected, mainly from the Non-Annex I countries. Wastewater emissions of CH4 and N2O from developing countries are also rising rapidly with increasing urbanization and population. Moreover, because the wastewater emissions in Table TS.13 are based on human sewage only and are not available for all developing countries, these emissions are underestimated (high agreement, medium evidence) [10.1, 10.2, 10.3, 10.4].

Table TS.13: Trends for GHG emissions from waste using 1996 and 2006 UNFCCC inventory guidelines, extrapolations and BAU projections (MtCO2-eq, rounded) [Table 10.3].

Source 1990 1995 2000 2005 2010 2015 2020 Notes 
Landfill CH4 550 585 590 635 700 795 910 Averaged using 1996/2006 guidelines 
Wastewatera CH4 450 490 520 590 600 630 670 1996 guidelines 
Wastewatera N2O 80 90 90 100 100 100 100 1996 guidelines 
Incineration CO2 40 40 50 50 50 60 60 2006 guidelines 
Total 1120 1205 1250 1375 1450 1585 1740   

Note: