Editing IPCC:AR6/WGII/Chapter-9 (section)

==== 9.8.2.4 Observed Impacts and Projected Risks on Livestock ====

<div id="h3-49-siblings" class="h3-siblings"></div>

Livestock systems in Africa are already being affected by changes in climate through increased precipitation variability leading to decreasing fodder availability ( [[#Sloat--2018|Sloat et al., 2018]] ; [[#Stanimirova--2019|Stanimirova et al., 2019]] ). More than twice as many countries in Africa have experienced increases in precipitation variability in the last century than decreases ( [[#Sloat--2018|Sloat et al., 2018]] ). Fodder availability is also being impacted by woody plant encroachment—the increase in shrub and tree cover—which has increased by 10% on subsistence grazing lands and 20% on economically important grazing lands in south Africa in the last 60 years ( [[#Stevens--2016|Stevens et al., 2016]] ), and is driven in part by climatic factors (see [[#9.6.1.1|Section 9.6.1.1]] ). Increased temperature and precipitation have contributed to the expanding range, especially in east and southern Africa, of several ixodid tick species which carry economically important livestock diseases ( [[#Nyangiwe--2018|Nyangiwe et al., 2018]] ).

Pastoralists in Africa perceive the climate as already changing and report more erratic and reduced rainfall, prolonged and more frequent droughts and a rise in temperature ( [[#Sanogo--2017|Sanogo et al., 2017]] ; [[#Kimaro--2018|Kimaro et al., 2018]] ). They also report reduced milk production, increased deaths and disease outbreaks in their herds due to malnutrition and starvation resulting from the shortages in forage and water ( [[#Kimaro--2018|Kimaro et al., 2018]] ). Additional research is required to attribute precipitation variability to human-induced climate change (see [[#9.5|Section 9.5]] ), and to evaluate the relative contributions of climate change and management to disease vector extent.

Future climate change will have compounding impacts on livestock, including negative impacts on fodder availability and quality, availability of drinking water, direct heat stress and the prevalence of livestock diseases ( [[#Nardone--2010|Nardone et al., 2010]] ; [[#Rojas-Downing--2017|Rojas-Downing et al., 2017]] ; [[#Godde--2021|Godde et al., 2021]] ). Climate change is projected to negatively affect fodder availability ( [[#Briske--2017|Briske, 2017]] ) because overall rangeland net primary productivity (NPP) by 2050 is projected to decrease 42% under RCP4.5 (2°C global warming) and 46% under RCP8.5 (2.4°C global warming) for western sub-Saharan Africa, compared to a 2000 baseline ( [[#Boone--2018|Boone et al., 2018]] ). NPP is also projected to decline by 37% in southern Africa, 32% in north Africa and 5% in both east Africa and central Africa by 2050 under RCP8.5 (2.4°C global warming) ( [[#Boone--2018|Boone et al., 2018]] ). For example, in Zimbabwe by 2040–2070, net revenues from livestock production, compared to a 2011 survey, are projected to decline by 8–32% under RCP4.5 for 2°C and 11–43% under RCP8.5 for 2.7°C global warming due to a decline in fodder availability ( [[#Descheemaeker--2018|Descheemaeker et al., 2018]] ). The available literature does not comprehensively capture the economic implications of climate-related impacts on livestock production across Africa.

Fodder quality, critical for animal health and weight gain, is at risk from climate change as increases in temperature, elevated CO 2 and water stress have been shown to reduce dry matter digestibility and nitrogen content for C 3 grasses ( [[#Augustine--2018|Augustine et al., 2018]] ), tropical C 4 grasses ( [[#Habermann--2019|Habermann et al., 2019]] ) and fodder crops such as Lucerne/Alfalfa ( [[#Polley--2013|Polley et al., 2013]] ; [[#Thivierge--2016|Thivierge et al., 2016]] ).

Climate change is projected to threaten water availability for livestock. Droughts in Africa have become more intense, frequent and widespread in the last 50 years ( [[#Masih--2014|Masih et al., 2014]] ), and progressive increase in droughts between 3- and 20-fold under climate change up to 3°C of warming are projected for most of Africa ( [[#9.5|Section 9.5]] ). In the Klela basin in Mali by 2050, groundwater recharge is projected to decline by 49% and groundwater storage by 24% under RCP8.5 (2.4°C global warming) compared to the 2006 baseline ( [[#Toure--2017|Toure et al., 2017]] ). Water availability for livestock during drought is a major concern for many African pastoralists including but not limited to those in Zimbabwe ( [[#Dzavo--2019|Dzavo et al., 2019]] ) and Nigeria ( [[#Ayanlade--2019|Ayanlade and Ojebisi, 2019]] ). Increased livestock mortality and livestock price shocks have been associated with droughts in Africa, as well as being a potential pathway for climate-related conflict ( [[#Catley--2014|Catley et al., 2014]] ; see Box 9.9; [[#Maystadt--2014|Maystadt and Ecker, 2014]] ).

Heat stress may already be the largest factor impacting livestock production in many regions in Africa ( [[#El-Tarabany--2017|El-Tarabany et al., 2017]] ; [[#Pragna--2018|Pragna et al., 2018]] ), as the combination of high temperatures and high relative humidity can be dangerous for livestock and has already decreased dairy production in Tunisia ( [[#Amamou--2018|Amamou et al., 2018]] ). Climate change is projected to increase heat stress for all types of livestock, especially in the tropics (Figure 9.24; [[#Lallo--2018|Lallo et al., 2018]] ). More studies quantifying the impact of heat stress on other types of livestock production loss are needed in Africa ( [[#Rahimi--2021|Rahimi et al., 2021]] ).

<div id="_idContainer075" class="Figure"></div>

[[File:f05a4c8929a6a6a995c432f95aaae706 IPCC_AR6_WGII_Figure_9_024.png]]

'''Figure 9.24 |''' '''Severe heat stress duration for cattle in Africa is projected to increase with increasing global warming.'''

'''(a)''' Number of days per year with severe heat stress in the historical climate (1985–2014).

'''(b)''' Historical cattle exposure to severe heat. Cattle density data from [[#Gilbert--2018|Gilbert et al. (2018)]] .

'''(c, d)''' Projected increase in the number of days per year with severe heat stress for a global warming level of 1.5°C and 3.75°C. Severe heat stress for cattle is projected to become much more extensive in the future in Africa at increased global warming levels. Strong mitigation would substantially limit the spatial extent and the duration of cattle heat stress across Africa. Heat stress is estimated using the Temperature Humidity Index with a value greater than 79 considered the onset of severe heat stress (Livestock Weather Safety Index) ( [[#Lallo--2018|Lallo et al., 2018]] ). Global warming of 1.5°C used scenario SSP1–2.6 and global warming of 3.75°C used SSP5-8.5, both for 2070–2099 (12 climate models from [[#O’Neill--2016|O’Neill et al., 2016]] ; [[#Tebaldi--2021|Tebaldi et al., 2021]] ). Global warming levels were calculated using a baseline for pre-industrial global mean temperature of 1850–1900.

Climate change will impact livestock disease prevalence primarily through changes in vector dynamics or range ( [[#Abdela--2016|Abdela and Jilo, 2016]] ; [[#Semenza--2018|Semenza and Suk, 2018]] ). African Rift Valley Fever (RVF) and trypanosomiasis are positively associated with extreme climate events (droughts and ENSO) ( [[#Bett--2017|Bett et al., 2017]] ) and are projected to expand in range under climate change ( [[#Kimaro--2017|Kimaro et al., 2017]] ; [[#Mweya--2017|Mweya et al., 2017]] ). More quantitative estimates of projected risk from diseases are needed.

<div id="9.8.3" class="h2-container"></div>

<span id="adapting-to-climate-variability-and-change-in-agriculture"></span>