Editing IPCC:AR6/SR15/Chapter-2 (section)

== 2.3.1 Range of Assumptions Underlying 1.5°C Pathways ==

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Earlier assessments have highlighted that there is no single pathway to achieve a specific climate objective (e.g., Clarke et al., 2014) <sup>[[#fn:r132|132]]</sup> . Pathways depend on the underlying development processes, and societal choices, which affect the drivers of projected future baseline emissions. Furthermore, societal choices also affect climate change solutions in pathways, like the technologies that are deployed, the scale at which they are deployed, or whether solutions are globally coordinated. A key finding is that 1.5°C-consistent pathways could be identified under a considerable range of assumptions in model studies despite the tightness of the 1.5°C emissions budget (Figures 2.4, 2.5) (Rogelj et al., 2018) <sup>[[#fn:r133|133]]</sup> .

The AR5 provided an overview of how differences in model structure and assumptions can influence the outcome of transformation pathways (Section 6.2 in Clarke et al., 2014 <sup>[[#fn:r134|134]]</sup> , as well as Table A.II.14 in Krey et al., 2014b) <sup>[[#fn:r135|135]]</sup> and this was further explored by the modelling community in recent years with regard to, e.g., socio-economic drivers (Kriegler et al., 2016; Marangoni et al., 2017; Riahi et al., 2017) <sup>[[#fn:r136|136]]</sup> , technology assumptions (Bosetti et al., 2015; Creutzig et al., 2017; Pietzcker et al., 2017) <sup>[[#fn:r137|137]]</sup> , and behavioural factors (van Sluisveld et al., 2016; McCollum et al., 2017) <sup>[[#fn:r138|138]]</sup> .

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