By Yakobo Bura – Art in Tanzania internship

Environmental Advocacy Program

Climate Change

Introduction

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

The impact of climate change in Tanzania is dynamic and varies among regions, as they are affected in different ways. While other areas 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 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 the themes and 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 decreased significantly in Tanzania, especially in recent years, and is expected to continue decreasing by the middle of the century.

Climate change has been a major constraint to agricultural productivity (crop production) in Tanzania because, in addition to other deficiencies in the sector, the type of crop production practised depends solely on rainfall.

 Within the noise of a naturally variable climate, scientists have detected a gradual warming and wetting trend in Tanzania over the past 100 years, of approximately 0.5 °C and 10-20%, respectively. Exceptionally wet years at the beginning of the 1960s are primarily 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 the 2010 International Federation of Red Cross and Red Crescent Societies. However, more recently produced scenarios using downscaled models for East Africa suggest that central Tanzania may experience a drying trend. Still, the uncertainties in these models are believed to be substantial.  There is also uncertainty regarding how climate change will impact extreme events, such as floods, droughts, heatwaves, and storms in the tropics.

 The climate drivers for interannual and decadal rainfall variability in ENSO events and Indian Ocean dynamics, as well as models, do not show clear tendencies for these events.  However, Huntingdon et al. (2005), using four Global Circulation Models (GCMs), suggest that the number of arid and highly 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; however, it is essential to note that there is already considerable variability in seasonal rainfall totals.

 Future climate is based on historical behaviour, with adjustments made to reflect various greenhouse gas (GHG) emission scenarios. Few regionally downscaled models exist for East Africa or Tanzania, and those that do exist have embedded uncertainties, in part due to 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; however, care should be taken to communicate the uncertainties associated with these products.  The latter is often inferred from models operating over longer time scales, which inadequately capture decadal variability.  It also highlights the need for scientists and decision-makers to be able to communicate and work under uncertainty, which underscores the importance of improving the coverage and quality of the hydro-meteorological data sets required 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 temperatures. 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 periods 1980–1999 (representing the current climate) and 2080–2099 (representing the future).

Climate change impacts are likely to be felt through changes in variability rather than long-term shifts in average conditions; therefore, uncertainty surrounding changes in extreme events introduces uncertainty in the extent of impacts. 

That said, we can be pretty sure that over the next 20 to 100 years, mean annual temperatures will rise at an unprecedented rate compared to the last 10,000 years.  Over this period, sea levels are also expected to increase by between 0.1 and 1 metre, leading to inundation and flooding in coastal areas, particularly in the low-lying but densely populated regions of Dar es Salaam and Zanzibar. In summary, temperatures in Tanzania are expected to increase by up to 1.5 °C over 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, although there is less certainty regarding these predictions. This variability in temperature and rainfall affects crop production in Tanzania, and adaptive measures should be developed to mitigate the effects of climate change on crop production in Tanzania.

3.0 Common Crops Grown in Tanzania

Tanzania has experienced continuous growth in its agricultural sector and is primarily considered self-sufficient in its primary staple crop, maize.  Cassava, paddy, sorghum, and bananas are the second most widely grown staple crops by farmers in Tanzania. However, other crops are grown on a small scale. It is known that 68% of the Tanzanian workforce engages in farming, both in rural and urban areas. Whether grown on a small scale or large scale, both crops are affected by increasing temperatures and fluctuating rainfall patterns, causing a change in the production season and threatening the livelihoods of 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 spans, 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. Although climate change affects almost all crops negatively to some extent, an increase in rainfall or decrease could favour certain crops depending on the length of their growing seasons.

5.0 Impacts of climate change on crops production in Tanzania

The agricultural sector in Tanzania is particularly vulnerable to climate change because it is traditionally dependent on rainfall. Increasing temperature, decreased and/or unpredictable rainfall, increased evapotranspiration, and seasonal unpredictability have 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 previously grew perennial crops would be suitable for annual crops.  Furthermore, global warming tends to accelerate plant growth, reducing the length of growing seasons. With the increase in temperature, reduced rainfall, and changes in rainfall patterns, the average maize yield is expected to decrease by 33% nationwide. The exact crop yield could decrease by up to 84% in the central regions, 22% in the 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 those for coffee; however, cotton yields could decrease by 10%— 20% due to the impact of pests and diseases.

It has been projected that, although there will be a general increase in rainfall in most parts of Tanzania, some areas will experience reduced rainfall, resulting in severe droughts with negative consequences for crop 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, as well as rainfall variability, are the significant factors influencing crop production in Tanzania. Unreliable rainfall has consistently resulted in unexpectedly low crop yields in most parts of the country (Munishi et al., 2009). It has also been argued that by 2030, approximately 5% of the 4.4 million inhabitants of Tanzania’s central regions will suffer from hunger due to poor yields, even if there is no change in drought frequency and severity.

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

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

6.1 Current Adaptation/Mitigation Responses – Short Term

According to the 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 crop 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 crops 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 provides daily weather prediction and seasonal forecasts
  • Better use of climate and weather data, weather forecasts, and other management tools, including the 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 the 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,
  • Promoting Indigenous knowledge on the adaptive capacity to climate change impacts and capacity building on climate change.

7.0 Conclusion

Climate change is becoming a significant threat to crop production in Tanzania, as it causes an increase in temperature and fluctuations in rainfall patterns. In some cases, there is a rainfall delay to rain (onset rainfall) and off early, causing shrinkage of the production season, resulting in low production of both commercial and food crops.

Educating farmers about climate change adaptation and mitigation strategies is also critical. 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 can 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, including manufacturing, automobile, health, and agriculture. Consequently, various global initiatives and agreements exist aimed at reducing climate change (effects), to which Tanzania is a signatory and must therefore remain committed to achieving such goals as Sustainable Development Goal(s) (Climate Action). Following this review, it is envisioned that the climate will continue to impact crop production. These impacts will extend to the socio-economic aspects of rural communities, which are particularly vulnerable to the effects of climate change. It is essential to note that climate change does not occur in isolation, as its effects and resulting environmental alterations significantly impact 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

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