Editing IPCC:AR6/SRCCL/Chapter-1 (section)

=== 1.3.1 Targeted decarbonisation relying on large land-area need ===

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Most global future scenarios that aim to achieve global warming of 2°C or well below rely on bioenergy (BE; BECCS, with carbon capture and storage; Cross-Chapter Box 7 in Chapter 6) or afforestation and reforestation (de Coninck et al. 2018 <sup>[[#fn:r547|547]]</sup> ; Rogelj et al. 2018b <sup>[[#fn:r548|548]]</sup> ,a <sup>[[#fn:r549|549]]</sup> ; Anderson and Peters 2016 <sup>[[#fn:r550|550]]</sup> ; Popp et al. 2016 <sup>[[#fn:r551|551]]</sup> ; Smith et al. 2016 <sup>[[#fn:r552|552]]</sup> ) (Cross-Chapter Box 2 in Chapter 1). In addition to the very large area requirements projected for 2050 or 2100, several other aspects of these scenarios have also been criticised. For instance, they simulate very rapid technological and societal uptake rates for the land-related mitigation measures, when compared with historical observations (Turner et al. 2018 <sup>[[#fn:r553|553]]</sup> ; Brown et al. 2019 <sup>[[#fn:r554|554]]</sup> ; Vaughan and Gough 2016 <sup>[[#fn:r555|555]]</sup> ). Furthermore, ''confidence'' in the projected bioenergy or BECCS net carbon uptake potential is ''low'' , because of many diverging assumptions. This includes assumptions about bioenergy crop yields, the possibly large energy demand for CCS, which diminishes the net-GHG-saving of bioenergy systems, or the incomplete accounting for ecosystem processes and of the cumulative carbon-loss arising from natural vegetation clearance for bioenergy crops or bioenergy forests and subsequent harvest regimes (Anderson and Peters 2016 <sup>[[#fn:r556|556]]</sup> ; Bentsen 2017 <sup>[[#fn:r557|557]]</sup> ; Searchinger et al. 2017 <sup>[[#fn:r558|558]]</sup> ; Bayer et al. 2017 <sup>[[#fn:r559|559]]</sup> ; Fuchs et al. 2017 <sup>[[#fn:r560|560]]</sup> ; Pingoud et al. 2018 <sup>[[#fn:r561|561]]</sup> ; Schlesinger 2018 <sup>[[#fn:r562|562]]</sup> ). Bioenergy provision under politically unstable conditions may also be a problem (Erb et al. 2012 <sup>[[#fn:r563|563]]</sup> ; Searle and Malins 2015 <sup>[[#fn:r564|564]]</sup> ).

Large-scale bioenergy plantations and forests may compete for the same land area (Harper et al. 2018 <sup>[[#fn:r565|565]]</sup> ). Both potentially have adverse side effects on biodiversity and ecosystem services, as well as socio-economic trade-offs such as higher food prices due to land-area competition (Shi et al. 2013 <sup>[[#fn:r566|566]]</sup> ; Bárcena et al. 2014 <sup>[[#fn:r567|567]]</sup> ; Fernandez-Martinez et al. 2014 <sup>[[#fn:r568|568]]</sup> ; Searchinger et al. 2015 <sup>[[#fn:r569|569]]</sup> ; Bonsch et al. 2016 <sup>[[#fn:r570|570]]</sup> ; Creutzig et al. 2015 <sup>[[#fn:r571|571]]</sup> ; Kreidenweis et al. 2016 <sup>[[#fn:r572|572]]</sup> ; Santangeli et al. 2016 <sup>[[#fn:r573|573]]</sup> ; Williamson 2016 <sup>[[#fn:r574|574]]</sup> ; Graham et al. 2017 <sup>[[#fn:r575|575]]</sup> ; Krause et al. 2017 <sup>[[#fn:r576|576]]</sup> ; Hasegawa et al. 2018 <sup>[[#fn:r577|577]]</sup> ; Humpenoeder et al. 2018 <sup>[[#fn:r578|578]]</sup> ). Although forest-based mitigation could have co-benefits for biodiversity and many ecosystem services, this depends on the type of forest planted and the vegetation cover it replaces (Popp et al. 2014 <sup>[[#fn:r579|579]]</sup> ; Searchinger et al. 2015 <sup>[[#fn:r580|580]]</sup> ) (Cross-Chapter Box 2 in Chapter 1).

There is ''high confidence'' that scenarios with large land requirements for climate change mitigation may not achieve SDGs, such as no poverty, zero hunger and life on land, if competition for land and the need for agricultural intensification are greatly enhanced (Creutzig et al. 2016 <sup>[[#fn:r581|581]]</sup> ; Dooley and Kartha 2018 <sup>[[#fn:r582|582]]</sup> ; Hasegawa et al. 2015 <sup>[[#fn:r583|583]]</sup> ; Hof et al. 2018 <sup>[[#fn:r584|584]]</sup> ; Roy et al. 2018 <sup>[[#fn:r585|585]]</sup> ; Santangeli et al. 2016 <sup>[[#fn:r586|586]]</sup> ; Boysen et al. 2017 <sup>[[#fn:r587|587]]</sup> ; Henry et al. 2018 <sup>[[#fn:r588|588]]</sup> ; Kreidenweis et al. 2016 <sup>[[#fn:r589|589]]</sup> ; UN 2015 <sup>[[#fn:r590|590]]</sup> ). This does not mean that smaller-scale land-based climate mitigation could not have positive outcomes for then achieving these goals (e.g., Sections 6.2, and 4.5, Cross-Chapter Box 7 in Chapter 6).

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