Quantifying trends of rainfall and temperature extremes over Central Tanzania to guide targeting of climate smart technologies
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We thank farmers and local partners in Africa RISING sites for their contributions to this work. We also acknowledge the
support of all donors which globally support the work of the CGIAR centers and their partners through their
contributions to the CGIAR system
Climate variability have significant impacts on resilience and productivity of
agro-ecosystems. Over 70% of livelihoods in ESA region depends on rain-
fed and low input agriculture that is highly vulnerable to climate vulnerability.
Determining the magnitude of change for key climate variables over space
& time is important to guide targeting of climate smart technologies.
Quantifying the magnitude and significance of climatic trends over space
and time in Africa is challenging due to low density of weather stations and
proportionately high gaps of existing gauge data. Gridded time series of
climate data generated from remote sensing platforms could provide
plausible alternative for measuring the trends of climate change in data
limiting context. This study investigate the magnitude and significance of
spatial-temporal trends of 37 years’ (1981 to 2017) time series gridded data
for rainfall, maximum and minimum temperature over six countries in ESA.
Here we demonstrate a case of Kongwa and Kiteto Districts located in semi-
arid zone in Central Tanzania.
Key words: Satellite time series, climatic extremes, resilience
Materials and Methods
This study uses 37 years record of monthly time series gridded
precipitation, minimum and maximum temperatures data from TerraClimate
database. A modified Mann-Kendal test and the Sen’s slope estimator were
respectively utilized to determine the significance of trends and the
magnitude of the trends per every pixel.
Results and Discussion
Rainfall showed significant negative trend in October and May (-0.01 to –
1.6 mm yr-1, Fig. 1). The two extreme temperatures showed a consistent
significant warming trend (+0.001 to +0.057 oC yr-1) recorded across the two
districts in all months although increase of Tmax in March to May was not
significant (Fig 2 & 3). Warming trend was most sever in months of
December. The observed trends points to increasing moisture and heat
stress in the two districts that could decrease agricultural productivity.
• Evaluate effectiveness of Africa RISING technologies (improved maize
varieties and Soil and water conservation measures) to cope with
observed drying and warming trends in comparison with farmers
• Utilize the observed trends to prioritize targeting of appropriate climate
Fig. 1: Rainfall trends over Kongwa & Kiteto districts derived from time series of TerraClimate
layers for 37 years starting 1981 to 2017
Quantifying trends of rainfall and temperature extremes over Central Tanzania
to guide targeting of climate smart technologies
International Institute of Tropical Agriculture (IITA), Tanzania1, Sokoine University, Tanzania2
1Francis Muthoni, 1Exavery Kigosi, 2Shitindi Mawazo
Fig. 3: Prevalent positive warming trend of Tmin (oC yr-1) over Kongwa and Kiteto Districts in
Cental of Tanzania. December experienced the highest increase of Tmin over the 37 years
Fig. 2: The trends of Tmax (oC yr-1) over Kongwa Kiteto Districts in Central of Tanzania
reflect the general warming trend except March to May