Fodder Security and Climate Change

Transcription

1 Fodder Security and Climate Change Trygve Berg, Norwegian University of Life Sciences Acknowledgement: Thanks to Dr Sandeep Sukumaran, Department of Geosciences, UiO who made the climate trend and climate scenario analyses for this study Thanks to professor Adugna Tolera, Ethiopia for discussions on pastoral vulnerability and adaptation to climate change

2 The importance of cattle Are cattle important for livelihood in SS Africa? A rinderpest-epidemic starting on the coast of Eritrea in 1888 reached to South Africa in 1896; it provides a natural experiment that gives us some answers. In Ethiopia it killed an estimated 90 percent of the cattle and caused the worst famine ever recorded in Ethiopian history. Also in southern Africa lack of ploughing oxen and meat resulted in widespread famine. Transport, depending on ox-carts broke down and isolated huge areas. Grasses grew tall and rank and became too rough for sheep and goats. The social fabric of pastoral communities also broke down and many people migrated to the mines. Some people rebelled against the white man s rule.

3 Does climate change threaten cattle-dependent people? Rainfall and temperature affect vegetation Growth Feed quality Seasonality of feed supply and feed quality Temperature affects the animals Heat load Drinking needs Mobility

4 Crops, cattle, and climate vulnerability Crops depend on climate during the growing season. The livestock depend on the entire annual cycle. In crop production unfavourable rainfall distribution can be mitigated by soil & water conservation, water harvesting, and supplementary irrigation. Yield reducing impacts from climate related factors can be compensated for by yield enhancing technologies. For livestock such options are not feasible. The traditional responses to unfavourable conditions are 1) Starving: Survival based on mobilisation of body reserves. 2) Migration to better pastures. Since both of those options may reach their limits the pastoral livestock sector appear particularly vulnerable to impacts of climate change.

5 Vulnerability to Climate Change in the pastoral sector: impacts and adaptation Which climatic variables affect production and survival in the pastoral sector in African rangelands, What are the trends and scanarios with respect to those climatic variables, What could be means and strategies for adapting pastoral production systems to projected changes in climates.

6 Temperature impacts on fodder quality Digestibility is negatively correlated to temperature. This negative correlation is stronger for grass than for other grazed vegetation. Quantitative effects of increased temperature on digestibility of grass varies from 0,5 to 1 percent units per degree C according to different studies. When feed quality is already low, this can have serious consequences. Herded animals depend on an annual cycle with high quality grazed vegetation early in the rainy season but gradual reduction in quality as the grasses grow tall and coarse leading to a dry season with very poor vegetation. Higher temperatures speed up reduction of feed quality. Thereby the productive period becomes shorter and the period with fodder quality below maintenance level becomes longer.

7 Rainfall Rainfall is essential for the primary production of the rangelands. Important features of rainfall include: Duration of the rainy season(s) Distribution of rainfall; likelihood of dry spells and floods Occurrence of unseasonal rainfall during dry season(s)

8 Areas projected to undergo > 20% reduction in length of growing period by 2050 (Thornton 2006)

9 Which climate data do we need? Most climate scenarios are too broad. To assess impacts, and thereby also be able to say something about how to adapt, we need more detailed climate scenarios. We need: Specific information for each climate zone, In areas with bimodal rainfall: Separate climate information for each season, For each growing season: Rainfall distribution rather than total rainfall, Global warming: Increased temperature with reference to level of temperature. Recent decades: Trend analyses Future: Climate scenarios

10 A test case: The Horn of Africa Our SoCoCa colleague Dr Sandeep Sukumaran could make the required analyses. We singled out the coordinates for two areas that are representative for highland farming areas and lowland pastoral areas. We broke down the data on three seasons: MAMJ JAS OND

11 CDD (Consecutive Dry Days) in highland (left) and lowland (right) (Sandeep, SoCoCa)

12 RR5 by season in highlands (left) and lowlands (right) (Sandeep, SoCoCa)

13 Climate records: What do they mean for pastoral people? Pastoralists must be able to absorb shocks in terms of irregular rainfall within and between years, With short productive periods the animals may approach the limit of their capacity to survive the aridity, feed scarcity and lowerquality feed-conditions of the dry season

14 Climate trends and productivity Main parameters of productivity: Reproduction, Milk yield, Meat production Signs of stress: Weakness and physical deterioration Vulnerability to diseases Lower calving rate and increased livestock mortality

15 Number of animals/household Mean cattle herd size/household Mean cattle mortality/household Years Mean cattle holding and mortality per household of sample Borana households in southern Ethiopia

16 Calving rate (%) 90 Calving rate of cattle from 1983 to 2003 in southern Ethiopia Years

17 Is supplementary feeding the way out? Surplus grass can be cut and dried at a time when feed quality is good and be conserved for use in the dry season. Other sources of supplementary feeding: At places where water is available; urea-treated crop residues. Adequately fed cows calve every year and thereby maintain a high productivity of the entire system Trend and way out: Fewer but more productive animals. The feasibility of this is strongly linked to commercial offtake.

18 Climate trends and adaptive response Increasing commercial off-take:

19 Scenarios: From now to end of the century Rainfall reliability in the MAMJ season in Highland (left) and lowland (right)

20 Scenarios: From now to end of the century Rainfall reliability in the JAS season in Highland (left) and lowland (right)

21 Scenarios: From now to end of the century Risk of dry spells in the MAMJ season in Highland (left) and lowland (right)

22 Scenarios: From now to end of the century Risk of dry spells in the JAS season in Highland (left) and lowland (right)

23 Scenarios: From now to end of the century Rainy days in the OND season in Highland (left) and lowland (right)

24 Temperature scenarios

25 Climate scenarios for the main season in the Central Highland of Ethiopia indicate: Reliable rainfall No risk of serious dry spells Temperature will not exceed what is optimal for crop growth Increased risk of unwanted rainfall during harvest time Comment: This may be representative of the areas and the season that provide most of Ethiopia s food grain production. With such scenarios climate change does not threaten national level food security in Ethiopia.

26 Areas that depend on the spring time season for cropping and growth of pastures face continued problems of irregular rainfall including high risk of destructive dry spells. Adding 3 degrees in lowland areas where mean max temperatures are already above 30 would have these consequences: Crop production depressed by temperature above optimal Feed quality (digestibility) of grass seriously reduced Added heat load on herded animals reducing productivity and range of mobility Comment: Climate change threatens local food security in areas depending on the spring time season for crop production and in lowland areas depending on pastoral production systems.