CLIMATE CHANGE EFFECT ON COMMON CROPS IN TANZANIA

By Yakobo Bura – Art in Tanzania internship

Introduction

Climate Change refers to a change in the state of the climate that can be identified (example by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forces, or to persistent anthropogenic changes in the composition of the atmosphere or in land use.

Note that the United Nations Framework Convention on Climate Change (UNFCCC), in its Article 1, defines climate change as: ‘a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.

The impact of climate change in Tanzania is dynamic and differs among regions as they are impacted in different ways. While other regions experience normal rainfall and temperature patterns, others have continued to experience temperature extremes, in this era of climate change, it is worthwhile to assess the effects of climate on common Tanzanian crops in order to design proper adaptation and mitigation measures that improve resilience (IPCC 2014; Serdeczny et al. 2017).

The Intergovernmental Panel on Climate Change (IPCC) has confirmed that there is substantial evidence that theme an extremes of climate variables have been changing in recent decades, and that rising atmospheric greenhouse gas concentrations could cause the trends of climate variables to intensify in the coming decades (Intergovernmental Panel on Climate Change 2014). Ahmed et al (2011) found that rainfall has significantly decreased in Tanzania, especially in the recent years, and is further expected to decrease by the mid of this century.

Climate change has been the major constraint to agriculture productivity (crop production) in Tanzania because in addition to other deficiencies that exist in the sector, the nature of crops production practiced depends solely on rainfall.

2.0 Climate trends and future scenarios

 Within the noise of naturally variable climate, scientists have detected a gradual warming and wetting trend in Tanzania over the past 100 years 17 of about 0.5 °C and 10-20% respectively.  Exceptionally wet years at the beginning of the 1960s are largely responsible for this increase in average rainfall and these changes cannot be attributed to human induced global warming with any certainty. 

Future climate scenarios have been developed based on 10 International Federation of Red Crescent and Red Cross Societies 2010. However more recently produced scenarios using downscaled models for East Africa suggest that Central Tanzania may see a drying trend17, but the uncertainties in these models are believed to be large.  There is also uncertainty as to how climate change will influence extreme events – floods, droughts, heat waves, and storms in the tropics.

 The climate drivers for inter annual and decadal rainfall variability in ENSO events and Indian Ocean dynamics and models do not show clear tendencies for these events.  However Huntingdon et al. (2005) using  four Global Circulation Models (GCMs) suggests that the number of extremely dry and extremely wet years will increase, and some models suggest that we will see a 20-30% increase in extreme wet seasons at a medium CO2  emission scenario. The seasonality of rainfall could also change in the future though it must be emphasized that there is already considerable variability in seasonal rainfall totals.

 Future climate based on historical behavior with adjustments made to reflect various greenhouse gas (GHG) emission scenarios. There are few regionally downscaled models for East Africa or Tanzania and those that exist have embedded uncertainties, in part because of the limited temporal and historical coverage of climate observations. 

There is an increasing demand for regional scale seasonal forecasts and decadal scenarios from decision makers but care should be taken in communicating the uncertainties in these products.  The latter are oft en inferred from models operating over much longer time scales which inadequately capture decadal variability.  As well as highlighting a need for scientists and decision makers to be able to communicate and work under uncertainty this flags the importance of improving the coverage and quality of the hydro-meteorological data sets needed for regional modelling.

Available studies and climate models give variable results for future rainfall trends but there is certainty in the picture they provide for future temperature. The IPCC Fourth Assessment Report provides a comprehensive review of climate model projections for different regions in Africa focusing on the change in climate between the period 1980–1999 (to represent the current climate) and 2080–2099 (to represent the future).

Climate change impacts are likely to be felt through changes in variability rather than the long term shifts in average conditions so this uncertainty around changes in extreme events brings uncertainty in the extent of impacts. 

That said we can be fairly certain that over the next 20 to 100 years mean annual temperatures will rise at a rate which has been unprecedented over the last 10 000 years.  Over this period, sea level will also rise by between 0.1 and 1 metre bringing inundation and flooding to coastal areas, particularly problematic in low lying but densely populated areas in Dar es Salaam and Zanzibar. In summary, temperatures are likely to increase in Tanzania by up to 1.5 °C in the next 20 years and by up to 4.3 °C by the 2080s.

Changes in rainfall patterns, total annual rainfall amounts and rainfall intensity are expected but there is less certainty here and this variability in temperature and rainfall affects the crops production in Tanzania as due to those effects the adaptive measures should be developed in order to reduce the climate change effects on crop production in Tanzania.

3.0 common crops grown in Tanzania

Tanzania records a continuous agricultural sector growth and is considered largely self-sufficient in its main staple crop maize.  Cassava, paddy, sorghum and bananas are the second most widely grown staple crops by farmers in Tanzania but there are also other crops that are grown in small scale; it is known that 68%of Tanzanians work force engages in farming, both in rural and urban areas. Whether grown in small scale or large scale both crops are affected by increasing in temperature and fluctuating rainfall patterns causing a change in production season, therefore threatening the livelihood of the farmers.

4.0 Severely affected crops by climate change in Tanzania

Mostly affected crops are the annual crops such as maize, rice, wheat, sorghum and millet, cassava, since they have short life span so the change in rainfall patterns (increase /decrease) and increase in temperature could affect these crops immediately and hence the impacts of loss will be experienced by the farmers within a short period of time. Although the climate change affects almost all crops negatively but in some extent increase in rainfall or decrease could favor the certain types of crops depending on the length of their growing seasons.

5.0 Impacts of climate change on crops production in Tanzania

The agriculture sector in Tanzania is particularly vulnerable to climatic change because it is customarily dependent on rainfall. Increasing temperature, decreased and/or unpredictable rainfall, increased evapotranspiration and seasonal unpredictability has consequences on drought, floods, crop yields, shifts in agro-ecological zones and agro-biodiversity and germplasm diversity, outbreaks of pest and diseases, Studies undertaken during the INC indicate that increase in temperature by 2⁰C-4⁰C would alter the distribution of the agro-ecological zones.

Consequently, areas that used to grow perennial crops would be suitable for annual crops.  Furthermore, global warming would tend to accelerate plant growth and hence reduce the length of growing seasons. With increase in temperature and reduced rainfall as well as change in rainfall patterns, average yield of maize is expected to decrease by 33% country wide. Yield of the same crop could decrease by up to 84% in the central regions, 22% in Northeastern highlands, 17% in the Lake Victoria region, and 10 – 15% in the Southern highlands.

However a temperature increase of 2-4⁰C, is likely to boost coffee production by 18% in bimodal rainfall areas and 16% in unimodal rainfall areas. The potential impacts of climate change on cotton production in Tanzania parallel that for coffee though cotton yields could decrease by 10% – 20% due to the impact of pests and diseases.

It has been projected that though there will be a general increase in rainfall in most parts of Tanzania some areas will experience reduced rainfall that will result into severe droughts with negative consequences on crops production. According to Mckinsey and Company (2009) rainfall is expected to decrease by 10 percent and variability in the annual rainfall will increase by 25 percent under a moderate change in climate, leading to more severe and frequent droughts.

Under a high climate change scenario rainfall in these regions would fall by 20% and variability would increase by 50%. Frequent and severe droughts and rainfall variability are the major factors influencing crop production in Tanzania and unreliable rainfall have always resulted into unexpected low crop yields in most parts of the country (Munishi et al, 2009). It has also been argued that by 2030 about 5% of the 4.4 million inhabitants of the central regions of Tanzania will suffer hunger from poor yields even if there is no change in drought frequency and severity.

6.0 Mitigation/adaptation response (short and long terms) in crops productions to climate change in Tanzania

Given the nature of impacts on the agriculture sector there has been an expressed need for differential adaptation strategy across various regions depending upon the certainty of projections, the mix of beneficial and adverse impacts, and the urgency and timing of such impacts. For the case of agriculture a key portfolio of adaptation responses would involve measures that boost the production of crops that will be negatively impacted by climate change such as maize and associated crops.

6.1 Current Adaptation/Mitigation Responses – Short Term

According to National Adaptation Plan (NAPA, 2007), current adaptation/mitigation measures in agriculture include;

• Increased irrigation,
• Increased use of manure and fertilizer,
• Better use of management tools including climate information. This would go hand in hand with measures that improve and boost the production of other food crops where they grow better
• Small scale irrigation and water harvesting 
• R&D on drought tolerant seed varieties,
• Agriculture extension activities and education on climate change and its impacts,
• Diversification of agriculture i.e. growing different types of crops on different land units

Example adaptation/ mitigation measures against climate change on crops production

6.2 Potential Adaptation/Mitigation Responses – Medium to Long Term

Further to the current adaptation measures there are several potential strategies for adaptation to climate change impact in the Agriculture sector, these include;

• Use of improved crop varieties,
• Breeding crop and livestock for drought and pest resistant varieties
• Pest risk analysis, improvement of pest management techniques, and pest tolerance, application of new technologies in pest management (IPM, breeding, biotechnology), alteration of pest management systems and Improvement of assessment tools for forecasting migratory pests
• Awareness creation on climate change and adaptation strategies,
• Strengthening early warning systems including information dissemination that provide daily weather prediction and seasonal forecasts
• Better use of climate and weather data, weather forecasts, and other management tools including development of long term monitoring systems to distinguish between natural environmental variability, effects of human activities and climate change and improved soil and water conservation measures,
• Improving irrigation potential including use of drip irrigation for specific regions,
• Development of sound land management practices including planning crop farming to align with more appropriate agro ecological zones including changes in crop rotation practices,
• Promotion of indigenous knowledge on adaptive capacity to climate change impacts and capacity building on climate change.

7.0 Conclusion

Conclusively the climate change is becoming the major threat to crops productions in Tanzania, climate change cause increase in temperature and fluctuation in rainfall patterns. In some cases there is the rainfall delay to rain (onset rainfall) and off early hence causing shrinkage of the production season, consequently results in to low production of both commercial and food crops.

It is also critical to provide education to farmers about climate change adaptation and mitigation strategies. Most importantly, the government should massively sensitize and build the capacities of rural communities, who are also the chief victims of climate change, to practice sustainable and environmentally friendly agricultural technologies such as conservation agriculture, farrowing, agroforestry, afforestation, integrated plant nutrient management, integrated pest management etc. that have the capacity to increase resilience to, or mitigate effects of climate change.

On a macro level, governments should consider investing in technologies with lower greenhouse gas emissions in key sectors of manufacturing, automobile, health and agriculture. Consequently, various global initiatives and agreements exist aimed at reducing climate change (effects), to which is Tanzania is a signatory, and must therefore remain committed to achieving such goals as Sustainable Development Goal(s) (Climate Action). In accordance with this review, it is envisioned that the climate will continue to have impacts on crops production. These impacts will extend to socioeconomic aspects of rural communities which are most vulnerable to climate change. It must be noted that, climate change does not occur in void, as its effects and resulting environmental alterations interact with agriculture.

8.0 References

Ahmed, S., N. Deffenbaugh, T. Hertel, D. Lobell, N. Ramankutty, A. Rios, and P. Rowhani. 2011. “Climate Volatility and Poverty Vulnerability in Tanzania.” Global Environmental Change 21: 46–55. doi:10.1016/j. gloenvcha.2010.10.003.  

Mckinsey & Company 2009. Economics of Climate Adaptation. Shaping Climate Resilient Development: A framework for decision making. Climate Works Foundation, Global Environmental Facility, Rockefeller Foundation, European Commission, Mckinsey & Company, Standard Chattered Bank, and Swiss Re. 159 pp

Munishi, P. K. T.  N. I Kihupi, S. J. Nindi, E. Mpeta, F. F. Tilya L. Chang’a and P. Yanda 2009. Profiling the Climate of Tanzania for Climate Change Mitigation and Adaptation. Unpublished Report, Sokoine University of Agriculture Morogoro Tanzania 53pp

Munishi PKT, Deo Shirima, Happiness Jackson and Halima Kilungu 2010. Analysis of Climate Change and its Impacts on Productive Sectors, Particularly Agriculture in Tanzania