Editing IPCC:AR6/SR15/Chapter-3 (section)

== 3.5.5.6 Rainforests ==

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A large portion of rainfall over the world’s largest rainforests is recirculated (e.g., Lenton et al., 2008) <sup>[[#fn:r1245|1245]]</sup> , which raises the concern that deforestation may trigger a threshold in reduced forest cover, leading to pronounced forest dieback. For the Amazon, this deforestation threshold has been estimated to be 40% (Nobre et al., 2016) <sup>[[#fn:r1246|1246]]</sup> . Global warming of 3°C–4°C may also, independent of deforestation, represent a tipping point that results in a significant dieback of the Amazon forest, with a key forcing mechanism being stronger El Niño events bringing more frequent droughts to the region (Nobre et al., 2016) <sup>[[#fn:r1247|1247]]</sup> . Increased fire frequencies under global warming may interact with and accelerate deforestation, particularly during periods of El Niño-induced droughts (Lenton et al., 2008; Nobre et al., 2016) <sup>[[#fn:r1248|1248]]</sup> . Global warming of 3°C is projected to reduce the extent of tropical rainforest in Central America, with biomass being reduced by about 40%, which can lead to a large replacement of rainforest by savanna and grassland (Lyra et al., 2017) <sup>[[#fn:r1249|1249]]</sup> . Overall, modelling studies (Huntingford et al., 2013; Nobre et al., 2016) <sup>[[#fn:r1250|1250]]</sup> and observational constraints (Cox et al., 2013) <sup>[[#fn:r1251|1251]]</sup> suggest that pronounced rainforest dieback may only be triggered at 3°C–4°C ( ''medium confidence'' ), although pronounced biomass losses may occur at 1.5°C– 2°C of global warming.

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