Editing IPCC:AR6/WGII/Chapter-11 (section)

===== 11.3.4.2.2 Projected impacts =====

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Some areas may experience increased pasture growth, but others may experience a decrease that cannot be fully offset by adaptation ( ''high confidence'' ) ( [[#Moore--2013|Moore and Ghahramani, 2013]] ; [[#Lieffering--2016|Lieffering, 2016]] ; [[#Kalaugher--2017|Kalaugher et al., 2017]] ). Climate change may modify the seasonality of pasture growth rates more than annual yields in New Zealand ( [[#Lieffering--2016|Lieffering, 2016]] ). In eastern parts of Queensland, climate change impacts on pasture growth are equivocal, with simple empirical models suggesting a decrease in net primary productivity ( [[#Liu--2017|Liu et al., 2017]] ), while mechanistic models that include increases in length of the growing season and the beneficial effects of CO 2 fertilisation indicate increases in pasture growth ( [[#Cobon--2020|Cobon et al., 2020]] ). In Tasmania, annual pasture production is projected to increase by 13–16%, even with summer growth projected to decline with increased interannual variability, resulting in a projected increase in milk yields by 3–16% per annum ( [[#Phelan--2015|Phelan et al., 2015]] ).

Extreme climatic events (droughts, floods and heatwaves) are projected to adversely impact productivity for livestock systems ( ''medium confidence'' ). This includes reduced pasture growth rates between 3–23% by 2070 from late spring to autumn and elevated growth in winter and early spring ( [[#Cullen--2009|Cullen et al., 2009]] ; [[#Hennessy--2016|Hennessy et al., 2016]] ; [[#Chang-Fung-Martel--2017|Chang-Fung-Martel et al., 2017]] ). Heavy rainfall and storms are projected to lead to increased erosion, particularly in extensively grazed systems on steeper land, reducing productivity for decades, reducing soil carbon ( [[#Orwin--2015|Orwin et al., 2015]] ) and increasing sedimentation. Increased heat stress in livestock is projected to decrease milk production and livestock reproduction rates ( ''high confidence'' ) ( [[#Nidumolu--2014|Nidumolu et al., 2014]] ; [[#Ausseil--2019b|Ausseil et al., 2019b]] ; [[#Lees--2019|Lees et al., 2019]] ). In Australia, the average number of moderate to severe heat stress days for livestock is projected to increase 12–15 d by 2025 and 31–42 d by 2050 compared to 1970–2000 ( [[#Nidumolu--2014|Nidumolu et al., 2014]] ). In New Zealand, an extra 5 (RCP2.6) to 7 (RCP8.5) moderate heat stress days per year are projected for 2046–2060 ( ''high confidence'' ) ( [[#Ausseil--2019b|Ausseil et al., 2019b]] ), which would especially affect animals transported long distances ( [[#Zhang--2019|Zhang and Phillips, 2019]] ) and strain the cold chains needed to deliver meat and dairy products safely. The distribution of existing and new pests and diseases are projected to increase, for example, new tick- and mosquito-borne diseases such as bovine ephemeral fever ( [[#Kean--2015|Kean et al., 2015]] ).

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