Editing IPCC:AR6/SRCCL/Chapter-5 (section)

==== 5.2.2.2 Impacts on livestock production systems ====

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Livestock systems are impacted by climate change mainly through increasing temperatures and precipitation variation, as well as atmospheric carbon dioxide (CO <sub>2</sub> ) concentration and a combination of these factors. Temperature affects most of the critical factors of livestock production, such as water availability, animal production and reproduction, and animal health (mostly through heat stress) (Figure 5.5). Livestock diseases are mostly affected by increases in temperature and precipitation variation (Rojas-Downing et al. 2017 <sup>[[#fn:r260|260]]</sup> ). Impacts of climate change on livestock productivity, particularly of mixed and extensive systems, are strongly linked to impacts on rangelands and pastures, which include the effects of increasing CO <sub>2</sub> on their biomass and nutritional quality. This is critical considering the very large areas concerned and the number of vulnerable people affected (Steinfeld 2010 <sup>[[#fn:r261|261]]</sup> ; Morton 2007 <sup>[[#fn:r262|262]]</sup> ). Pasture quality and quantity are mainly affected through increases in temperature and CO <sub>2</sub> , and precipitation variation.

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'''Figure 5.5'''

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'''Impacts of climate change on livestock (based on Rojas-Downing et al. 2017)'''
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[[File:a4de770f2066bcabf96bc4ac56c0150b Figure-5.5-1024x899.jpg]]

Impacts of climate change on livestock (based on Rojas-Downing et al. 2017) <sup>[[#fn:r1423|1423]]</sup>

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Among livestock systems, pastoral systems are particularly vulnerable to climate change (Dasgupta et al. 2014 <sup>[[#fn:r263|263]]</sup> ) (see Section 5.2.2.6 for impacts on smallholder systems that combine livestock and crops). Industrial systems will suffer most from indirect impacts leading to rises in the costs of water, feeding, housing, transport and the destruction of infrastructure due to extreme events, as well as an increasing volatility of the price of feedstuff which increases the level of uncertainty in production (Rivera-Ferre et al. 2016b <sup>[[#fn:r264|264]]</sup> ; Lopez-i-Gelats 2014 <sup>[[#fn:r265|265]]</sup> ). Mixed systems and industrial or landless livestock systems could encounter several risk factors mainly due to the variability of grain availability and cost, and low adaptability of animal genotypes (Nardone et al. 2010 <sup>[[#fn:r266|266]]</sup> ).

Considering the diverse typologies of animal production, from grazing to industrial, Rivera-Ferre et al. (2016b) <sup>[[#fn:r267|267]]</sup> distinguished impacts of climate change on livestock between those related to extreme events and those related to more gradual changes in the average of climate-related variables. Considering vulnerabilities, they grouped

the impacts as those impacting the animal directly, such as heat and cold stress, water stress, physical damage during extremes; and others impacting their environment, such as modification in the geographical distribution of vector-borne diseases, location, quality and quantity of feed and water and destruction of livestock farming infrastructures.

With severe negative impacts due to drought and high frequency of extreme events, the average gain of productivity might be cancelled by the volatility induced by increasing variability in the weather. For instance, semi-arid and arid pasture will likely have reduced livestock productivity, while nutritional quality will be affected by CO <sub>2</sub> fertilisation (Schmidhuber and Tubiello 2007 <sup>[[#fn:r268|268]]</sup> ).

'''Observed impacts''' . Pastoralism is practiced in more than 75% of countries by between 200 and 500 million people, including nomadic communities, transhumant herders, and agropastoralists (McGahey et al. 2014 <sup>[[#fn:r269|269]]</sup> ). Observed impacts in pastoral systems reported in the literature include decreasing rangelands, decreasing mobility, decreasing livestock numbers, poor animal health, overgrazing, land degradation, decreasing productivity, decreasing access to water and feed, and increasing conflicts for the access to pasture land ( ''high confidence'' ) (López-i-Gelats et al. 2016 <sup>[[#fn:r270|270]]</sup> ; Batima et al. 2008 <sup>[[#fn:r271|271]]</sup> ; Njiru 2012 <sup>[[#fn:r272|272]]</sup> ; Fjelde and von Uexkull 2012 <sup>[[#fn:r273|273]]</sup> ; Raleigh and Kniveton 2012 <sup>[[#fn:r274|274]]</sup> ; Egeru 2016 <sup>[[#fn:r275|275]]</sup> ).

Pastoral systems in different regions have been affected differently. For instance, in China changes in precipitation were a more important factor in nomadic migration than temperature (Pei and Zhang 2014 <sup>[[#fn:r276|276]]</sup> ). There is some evidence that recent years have already seen an increase in grassland fires in parts of China and tropical Asia (IPCC 2012 <sup>[[#fn:r277|277]]</sup> ). In Mongolia, grassland productivity has declined by 20–30% over the latter half of the 20th century, and ewe average weight reduced by 4 kg on an annual basis, or about 8% since 1980 (Batima et al. 2008 <sup>[[#fn:r278|278]]</sup> ). Substantial decline in cattle herd sizes can be due to increased mortality and forced off-take (Megersa et al. 2014 <sup>[[#fn:r279|279]]</sup> ). Important, but less studied, is the impact of the interaction of grazing patterns with climate change on grassland composition. Spence et al. (2014) <sup>[[#fn:r280|280]]</sup> showed that climate change effects on Mongolia mountain steppe could be contingent on land use.

Conflicts due to resource scarcity, as well as other socio-political factors (Benjaminsen et al. 2012 <sup>[[#fn:r281|281]]</sup> ) aggravated by climate change, has differentiated impact on women. In Turkana, female-headed households have lower access to decision-making on resource use and allocation, investment and planning (Omolo 2011 <sup>[[#fn:r282|282]]</sup> ), increasing their vulnerability (Cross-Chapter Box 11 in Chapter 7, Section 5.1.3).

Non-climate drivers add vulnerability of pastoral systems to climate change (McKune and Silva 2013 <sup>[[#fn:r283|283]]</sup> ). For instance, during environmental disasters, livestock holders have been shown to be more vulnerable to food insecurity than their crop-producing counterparts because of limited economic access to food and unfavourable market exchange rates (Nori et al. 2005 <sup>[[#fn:r284|284]]</sup> ). Sami reindeer herders in Finland showed reduced freedom of action in response to climate change due to loss of habitat, increased predation, and presence of economic and legal constraints (Tyler et al. 2007 <sup>[[#fn:r285|285]]</sup> ; Pape and Löffler 2012 <sup>[[#fn:r286|286]]</sup> ). In Tibet, emergency aid has provided shelters and privatised communally owned rangeland, which have increased the vulnerability of pastoralists to climate change (Yeh et al. 2014 <sup>[[#fn:r287|287]]</sup> ; Næss 2013 <sup>[[#fn:r288|288]]</sup> ).

'''Projected impacts''' . The impacts of climate change on global rangelands and livestock have received comparatively less attention than the impacts on crop production. Projected impacts on grazing systems include changes in herbage growth (due to changes in atmospheric CO <sub>2</sub> concentrations and rainfall and temperature regimes) and changes in the composition of pastures and in herbage quality, as well as direct impacts on livestock (Herrero et al. 2016b <sup>[[#fn:r289|289]]</sup> ). Droughts and high temperatures in grasslands can also be a predisposing factor for fire occurrence (IPCC 2012 <sup>[[#fn:r290|290]]</sup> ).

'''Net primary productivity, soil organic carbon, and length of growing period''' . There are large uncertainties related to grasslands and grazing lands (Erb et al. 2016) <sup>[[#fn:r291|291]]</sup> , especially in regard to net primary productivity (NPP) (Fetzel et al. 2017 <sup>[[#fn:r292|292]]</sup> ; Chen et al. 2018 <sup>[[#fn:r293|293]]</sup> ). Boone et al. (2017) estimated that the mean global annual net primary production (NPP) in rangelands may decline by 10 gC m <sup>–2</sup> yr <sup>–1</sup> in 2050 under RCP8.5, but herbaceous NPP is likely to increase slightly (i.e., average of 3 gC m <sup>–2</sup> yr <sup>–1</sup> ) (Figure 5.6). Results of a similar magnitude were obtained by Havlík et al. (2015) <sup>[[#fn:r294|294]]</sup> , using EPIC and LPJmL on a global basis. According to Rojas-Downing et al. (2017) <sup>[[#fn:r295|295]]</sup> , an increase of 2°C is estimated to negatively impact pasture and livestock production in arid and semi-arid regions and positively impact humid temperate regions.

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'''Figure 5.6'''

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'''Ensemble simulation results for projected annual net primary productivity of rangelands as simulated in 2000 (top) and their change in 2050 (bottom) under emissions scenario RCP 8.5, with plant responses enhanced by CO2 fertilisation. Results from RCP 4.5 and 8.5, with and without positive effects of atmospheric CO2 on plant production, differed considerably in magnitude […]'''
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[[File:179d1fa9d08265a7a2ce0afd43b2200e Figure-5.6-1024x1020.jpg]]

Ensemble simulation results for projected annual net primary productivity of rangelands as simulated in 2000 (top) and their change in 2050 (bottom) under emissions scenario RCP 8.5, with plant responses enhanced by CO <sub>2</sub> fertilisation. Results from RCP 4.5 and 8.5, with and without positive effects of atmospheric CO <sub>2</sub> on plant production, differed considerably in magnitude but had similar spatial patterns, and so results from RCP 8.5 with increasing production are portrayed spatially here and in other figures. Scale bar labels and the stretch applied to colours are based on the spatial mean value plus or minus two standard deviations (Boone et al. 2017) <sup>[[#fn:r1424|1424]]</sup> .

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Boone et al. (2017) <sup>[[#fn:r296|296]]</sup> identified significant regional heterogeneity in responses, with large increases in annual productivity projected in northern regions (e.g., a 21% increase in productivity in the USA and Canada) and large declines in western Africa (–46% in Sub-Saharan western Africa) and Australia (–17%). Regarding the length of growing period (LGP, average number of growing days per year) Herrero et al. (2016b) <sup>[[#fn:r297|297]]</sup> projected reductions in lower latitudes due to changes in rainfall patterns and increases in temperatures, which indicate increasing limitations of water. They identified 35°C as a critical threshold for rangeland vegetation and heat tolerance in some livestock species.

'''Rangeland composition''' . According to Boone et al. (2017), the composition of rangelands is projected to change as well (Chapter 3). Bare ground cover is projected to increase, averaging 2.4% across rangelands, with increases projected for the eastern Great Plains, eastern Australia, parts of southern Africa, and the southern Tibetan Plateau. Herbaceous cover declines are projected in the Tibetan Plateau, the eastern Great Plains, and scattered parts of the Southern Hemisphere. Shrub cover is projected to decline in eastern Australia, parts of southern Africa, the Middle East, the Tibetan Plateau, and the eastern Great Plains. Shrub cover could also increase in much of the Arctic and some parts of Africa. In mesic and semi-arid savannas south of the Sahara, both shrub and tree cover are projected to increase, albeit at lower productivity and standing biomass. Rangelands in western and south-western parts of the Isfahan province in Iran were found to be more vulnerable to future drying–warming conditions (Saki et al. 2018 <sup>[[#fn:r298|298]]</sup> ; Jaberalansar et al. 2017 <sup>[[#fn:r299|299]]</sup> ).

Soil degradation and expanding woody cover suggest that climate-vegetation-soil feedbacks catalysing shifts toward less productive, possibly stable states (Ravi et al. 2010 <sup>[[#fn:r300|300]]</sup> ) may threaten mesic and semi-arid savannas south of the Sahara (Chapters 3 and 4). This will also change their suitability for grazing different animal species; switches from cattle, which mainly consume herbaceous plants, to goats or camels are likely to occur as increases in shrubland occur.

'''Direct and indirect effects on livestock''' . Direct impacts of climate change in mixed and extensive production systems are linked to increased water and temperature stress on the animals potentially leading to animal morbidity, mortality and distress sales. Most livestock species have comfort zones between 10oC–30oC, and at temperatures above this animals reduce their feed intake 3–5% per additional degree of temperature (NRC 1981 <sup>[[#fn:r301|301]]</sup> ). In addition to reducing animal production, higher temperatures negatively affect fertility (HLPE 2012 <sup>[[#fn:r302|302]]</sup> ).

Indirect impacts to mixed and extensive systems are mostly related to the impacts on the feed base, whether pastures or crops, leading to increased variability and sometimes reductions in availability and quality of the feed for the animals (Rivera-Ferre et al. 2016b <sup>[[#fn:r303|303]]</sup> ). Reduced forage quality can increase CH <sub>4</sub> emissions per unit of gross energy consumed. Increased risk of animal diseases is also an important impact to all production systems (Bett et al. 2017 <sup>[[#fn:r304|304]]</sup> ). These depend on the geographical region, land-use type, disease characteristics, and animal susceptibility (Thornton et al. 2009 <sup>[[#fn:r305|305]]</sup> ). Also important is the interaction of grazing intensity with climate change. Pfeiffer et al. (2019) <sup>[[#fn:r306|306]]</sup> estimated that, in a scenario of mean annual precipitation below 500 mm, increasing grazing intensity reduced rangeland productivity and increased annual grass abundance.

Pastoral systems. In Kenya, some 1.8 million extra cattle could be lost by 2030 because of increased drought frequency, the value of the lost animals and production foregone amounting to 630 million USD (Herrero et al. 2010 <sup>[[#fn:r307|307]]</sup> ). Martin et al. (2014) <sup>[[#fn:r308|308]]</sup> assessed impacts of changing precipitation regimes to identify limits of tolerance beyond which pastoral livelihoods could not be secured and found that reduced mean annual precipitation always had negative effects as opposed to increased rainfall variability. Similarly, Martin et al. (2016) <sup>[[#fn:r309|309]]</sup> found that drought effects on pastoralists in High Atlas in Morocco depended on income needs and mobility options (see Section 5.2.2.6 for additional information about impacts on smallholder farmers).

In summary, observed impacts in pastoral systems include changes in pasture productivity, lower animal growth rates and productivity, damaged reproductive functions, increased pests and diseases, and loss of biodiversity ( ''high confidence'' ). Livestock systems are projected to be adversely affected by rising temperatures, depending on the extent of changes in pasture and feed quality, spread of diseases, and water resource availability ( ''high confidence'' ). Impacts will differ for different livestock systems and for different regions ( ''high confidence'' ). Vulnerability of pastoral systems to climate change is very high ( ''high confidence'' ), and mixed systems and industrial or landless livestock systems could encounter several risk factors mainly due to variability of grain availability and cost, and low adaptability of animal genotypes. Pastoral system vulnerability is exacerbated by non-climate factors (land tenure issues, sedentarisation programmes, changes in traditional institutions, invasive species, lack of markets, and conflicts) ( ''high confidence'' ).

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