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reports and biennial reports. Any remaining data gaps were addressed by using a set of
scientific global data sets. 35
95. As noted in paragraph 84 above, the estimated level of emissions communicated in
each INDC for the target years (2025 and 2030) includes only those sectors and gases
specified by each Party in its INDC. As a result, the aggregate level of emissions resulting
from the implementation of the communicated INDCs is a partial estimate that excludes
Parties that did not communicate an INDC as well as the sectors and gases that each Party
chose not to include in its INDC. In order to discuss that partial estimate in the global
context, total global emissions in 2025 and 2030 were estimated in accordance with
paragraph 85 above.
96. To derive the level of the emissions not covered by the communicated INDCs,
global emission scenarios 36 were adjusted to remove the reference emissions strictly
associated with the INDCs by extracting any relevant gas-, sector-, country- or regionspecific
growth rate. Additional details are available in the technical web-based annex.
97. Cumulative CO 2 emissions were calculated by assuming the same growth rates in
CO 2 and non-CO 2 emissions as the IPCC reference scenarios projected, starting from the
last available year of historical emission data in the underlying emission database. The
resulting share of CO 2 emissions was then applied to the linearly estimated trajectory of
GHG emissions between the last historical data point and estimated emission levels for
2020, 2025 and 2030. Consistent with the report of IPCC Working Group I, 37 future carbon
emissions were then summed for the cumulative emission estimate, starting after 2011.
98. The results presented in chapter II.E correspond to a 60 per cent range from the 20 th
percentile to the 80 th percentile across the set of a total of 304 emission estimates for 2025
and 2030, with 152 being different implementations of the ‘high’ and 152 being different
implementations of the ‘low’ emission estimates. Those estimates are taken from the
respective ends of any communicated INDC target ranges. The ‘high’ end aggregates all
unconditional central INDC targets (where a Party communicated only a single target) and
any upper end of ranges that were provided by a Party. The ‘low’ end similarly aggregates
all central INDC targets as well as the lower ends of the target ranges, if applicable. The
‘low’ variant was calculated by including any conditional targets, if available.
3. Key challenges and assumptions
99. The approach and methods described above include a number of uncertainties linked
to data availability and quality.
35 For a consistent aggregation of emissions, a gas-by-gas data basis was necessary, in order to allow the
conversion from different metrics, such as GWP SAR or GWP AR5 metrics into GWP AR4, which
was used consistently for the aggregation in this report. This is part of the reason why, in some cases,
complementary data sets were necessary in order to arrive at an estimate for the aggregate effect of
the INDCs. The primary complementary source of gas-by-gas data on the emissions of Parties not
included in Annex I to the Convention was the IPCC AR5 historical emission database (as shown in
figure SPM.1 of the contribution of Working Group II to the AR5), which is a composite database
including sources such as IEA, EDGAR and Houghton et al. (Houghton RA, van der Werf GR,
DeFries RS, Hansen MC, House JI, Le Quéré C, Pongratz J and Ramankutty N. 2012. Chapter G2
Carbon emissions from land use and land-cover change. Biogeosciences. 9: pp.5125–5142.), in
combination with data from the Food and Agriculture Organization of the United Nations, the Carbon
Dioxide Information Analysis Center and others.
36 The scenarios were taken from the IPCC AR5 scenario database, available at
.
37
Climate Change 2013: The Physical Science Basis. Available at
.
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