Editing IPCC:AR6/SR15/Chapter-4 (section)

====== Lead Authors ======

* Paolo Bertoldi (Italy)
* James Ford (United Kingdom, Canada)
* Richard Klein (Netherlands, Germany)
* Debora Ley (Guatemala, Mexico)
* Timmons Roberts (United States)
* Joeri Rogelj (Austria, Belgium)

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'''Mitigation'''

''1. Introduction''

There is ''high agreement'' that Nationally Determined Contributions (NDCs) are important for the global response to climate change and represent an innovative bottom-up instrument in climate change governance (Section 4.4.1), with contributions from all signatory countries (den Elzen et al., 2016; Rogelj et al., 2016; Vandyck et al., 2016; Luderer et al., 2018; Vrontisi et al., 2018) <sup>[[#fn:r927|927]]</sup> . The global emission projections resulting from full implementation of the NDCs represent an improvement compared to business as usual (Rogelj et al., 2016) <sup>[[#fn:r928|928]]</sup> and current policies scenarios to 2030 (den Elzen et al., 2016; Vrontisi et al., 2018) <sup>[[#fn:r929|929]]</sup> . Most G20 economies would require new policies and actions to achieve their NDC targets (den Elzen et al., 2016; Vandyck et al., 2016; UNEP, 2017b; Kuramochi et al., 2018) <sup>[[#fn:r930|930]]</sup> .

''2. The effect of NDCs on global greenhouse gas (GHG) emissions''

Several studies estimate global emission levels that would be achieved under the NDCs (e.g., den Elzen et al., 2016; Luderer et al., 2016; Rogelj et al., 2016, 2017; Vandyck et al., 2016; Rose et al., 2017; Vrontisi et al., 2018) <sup>[[#fn:r931|931]]</sup> . Rogelj et al. (2016) <sup>[[#fn:r932|932]]</sup> and UNEP (2017b) <sup>[[#fn:r933|933]]</sup> concluded that the full implementation of the unconditional and conditional NDCs are expected to result in global GHG emissions of about 55 (52–58) and 53 (50–54) GtCO <sub>2</sub> -eq yr <sup>−</sup> <sup>1</sup> , respectively (Cross-Chapter Box 11, Figure 1 below).

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