IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change CO2 emissions

Global growth in fossil fuel demand has a significant effect on the growth of energy-related CO2 emissions: both the IEA and the U.S. EIA project growth of more than 55% in their respective forecast periods. The IEA projects a 1.7% per year growth rate to 2030, while the U.S. EIA projects a 2.0% per year rate in the absence of additional policies. According to IEA projections, emissions will reach 40.4 GtCO2 in 2030, an increase of 14.3 GtCO2 over the 2004 level. SRES[14] (IPCC, 2000a) CO2 emissions from energy use for 2030 are in the range 37.2–53.6 GtCO2, which is similar to the levels projected in the EMF-21[15] (EMF, 2004) scenarios reviewed in Chapter 3, Section 3.2.2 (35.9–52.1 GtCO2). Relative to the approximately 25.5 GtCO2 emissions in 2000 (see Fig 1.1), fossil fuel-sourced CO2 emissions are projected to increase by 40–110% by 2030 in the absence of climate policies in these scenarios (see Figure 1.7).

Figure 1.7

Figure 1.7 Global GHG emissions for 2000 and projected baseline emissions for 2030 and 2100 from IPCC SRES and the post-SRES literature. The figure provides the emissions from the six illustrative SRES scenarios. It also provides the frequency distribution of the emissions in the post-SRES scenarios (5th, 25th, median, 75th, 95th percentile), as covered in Chapter 3. F-gases include HFCs, PFCs and SF6

As the bulk of the growing energy demand occurs in developing countries, the CO2 emission growth accordingly is dominated by developing countries. The latter would contribute two thirds to three quarters of the IEA-projected increase in global energy-related emissions. Developing countries, which accounted for 40% of total fossil fuel-related CO2 emissions in 2004, are projected to overtake the Organization for Economic Co-operation and Development (OECD) as the leading contributor to global CO2 fossil fuel emissions in the early part of the next decade.

The CO2 emission projections account for both growth in energy demand and changes in the fuel mix. The IEA projects the share of total energy-related emissions accounted for by gas to increase from 20% in 2004 to 22% in 2030, while the share of coal increases from 41% to 43% and oil drops by approximately 4%, from 39% to 35%, respectively, of the total. On the basis of sectoral shares at the global level, power generation grows from a 41% to a 44% share, while the 20% share of transport is unchanged. The fastest emissions growth rate is in power generation – at 2.0% per year – followed by transport at 1.7% per year. The industry sector grows at 1.6% per year, the residential/commercial sector at 1% per year and international marine and aviation emissions at 0.7% per year.

The SRES range of energy-related CO2 emissions for 2100 is much larger, 15.8–111.2 GtCO2, while the EMF-21 scenario range for 2100 is 53.6–101.4 GtCO2.

  1. ^  SRES is the IPCC Special Report on Emissions Scenarios (IPCC, 2000a). The ranges reported here are for the five SRES Marker scenarios.
  2. ^  EMF-21 Energy Modeling Forum Study 21: Multi-gas Mitigation scenarios (EMF, 2004)