9.4 (±56.3)

38.3 (±73.9)

-1.8 (±25)

-12.3 (±50.4)

11.4 (±31.9)

-1.6 (±56.2)

1.2 (±0.8)1.4 (±0.9)

1.6 (±1.3) 1.5 (±1.1)

1.7 (±1.4)

1.3 (±0.9)

Climatic changes for cassava- growing regions

Impacts of CC on cassava climate suitability

2030s

CAF EAF

NAF SAF

SAH

WAF

We use downscaled projections of 24 Global Climate Models (GCMs) for the SRES-A1B emissions scenario by 2030s period (2020-2049).

The GCMs predicts increases in t e m p e r a t u r e s between 1.2 and 2 °C, and changes in precipitation ranged between -39 to +64 mm/year across all Africa.

Predicted changes in climates as average of 24 GCMs (and uncertainties expressed as standard deviations), by Africa regions.

Annual mean temperature change (°C)

Total annual rainfall change (mm)

70%Countries with increases below 1.5 °C where the most production

is located.

>90%Cassava production is located in

WAF, EAF, CAF

~4%Of overall increase in yearly

predicted rainfall in the SAH.

Impact assessment methods are sensitive to uncertainties in climate data, and hence these must be considered when assessing crop responses to combinations of increasing temperatures, varied precipitation patterns and increased CO2 concentrations. There was a relatively strong disagreement in GCM signals even for temperature and the uncertainty related to GCMs in rainfall was high.

!

The EcoCrop model was used in assessing the impacts of climate change. It evaluates on a monthly basis if there are adequate climatic conditions within a growing season for temperature and precipitation and calculates the climatic suitability of the resulting interaction

between rainfall and temperature.

Africa regionsCAF: Central AfricaEAF: East AfricaNAF: North Africa

SAF: South AfricaSAH: SahelWAF: West Africa

Changes in cassava climatic suitability by 2030s as predicted by EcoCrop indicate increases in the vast majority of areas, and especially seem to occur in a greater proportion over currently cropped areas and where the most signi�cant production is reported.

Countries with the highest harvest area and overall suitability change (% ± SD)

Some cassava agroclimatological data

Impacts of CC on other staple crops

Above the optimal temperatures, cassava increases photosynthetic rates and branching.

17%area with loss in suitability

36%area with gain in suitability

47%area without

changes

Predicted changes in cassava suitability as average of 24GCMs

Variation amongst individual GCM predictions was signi�cant and predicted impacts with very high certainty (>80% GCMs predicting changes in the same direction).

7.2 km2 unchanged

3.3 km2 negatively impacted areas

5.5 km2 positively impacted areas

!

The most severe impacts were observed in WAF and the SAH, where predicted changes were negative in ~80% of the countries.

Nigeria0.2 (±3.2)

DR of the Congo−0.1 (±0.7)

Tanzania8.3 (±5.5)

Mozambique−0.6 (±4)

Angola3.1 (±6.6)

Ghana−0.6 (±2.9)

Uganda4.7 (±3.2)

Madagascar5.6 (±2.7)

Ivory Coast−0.3 (±1.5)

Cassava grows optimally in the range 25–29°C although it can withstand temperatures of up to 38°C.

Cassava is tolerant to within-season drought, but this depends on the timing, intensity and duration.

Low temperatures inhibit plant growth and reduce leaf production rate, biomass and roots yield but rarely kill the plant.

Impacts of climate change on cassava suitability in sub-regions of Africa (Average change in suitability)

WAF

SAH

SAF

NAF

EAF

CAF

-20 -10 0 10 20 30

Overall suitability change (%)

Boxplots are combinations of GCM-by-country predictions. Thick black vertical lines are the median, boxes show the first and third quartile and whiskers

extend 5% and 95% of the distributions

Boxplots are combinations of GCM-by-country predictions. Thick black vertical lines are the median, boxes show the first and third quartile and whiskers extend 5% and 95% of the distributions

Sorghum

Potato

Millet

Maize

Cassava

Beans

-50 -25 0 25Overall suitability change (%)

Banana

Sorghum

Potato

Millet

Maize

Cassava

Beans

Banana

Sorghum

Potato

Millet

Maize

Cassava

Beans

Banana

Sorghum

Potato

Millet

Maize

Cassava

Beans

Banana

Sorghum

Potato

Millet

Maize

Cassava

Beans

Banana

Sorghum

Potato

Millet

Maize

Cassava

Beans

Banana

WAFSAH

SAFNAF

EAFCAF

Impacts on pests and diseases

Abiotic breeding priorities

is the projected change in suitability across the continent. Cassava is actually positively impacted in many areas of Africa.

−3.7% to

+17.5%

Whilst most areas in Africa were predicted to experience decreases in overall suitability of the additional crops modeled, cassava always outperformed or (in the worst case) equaled the

average of these crops.

Conversely, for other major food staples, we found that they are all projected to experience negative impacts, with the

greatest impacts for:

Discrimination of areas according to gains and losses using the mean change in suitability of all crops but cassava. Typology: C: cassava, O: other crops; G: increase in suitability, L: decrease in suitability. For instance, “C:G, O:L” indicates that in that area cassava (C) increases in suitability (G), and all other crops in average (O) decrease suitability (L)

We then examined the challenges that cassava will likely face from pests and diseases through the use of ecological niche modeling for cassava mosaic disease, white�y, brown streak disease, and cassava mealybug. The �ndings show that the geographic distribution of these pests and diseases are projected to change, with both new areas opening up and areas where the pests and diseases are likely to move away or reduce in pressure.

Predicted changes in suitability of other staples (average among crops and GCMs)

In WAF, large negative impacts were predicted for potato (-15%,), beans

(-20%), and banana (-13%,), whereas millet, maize, and cassava were

predicted to remain the same. Sorghum showed positive impacts (10%)

In EAF, however, cassava showed the greatest

potential compared to all other crops (10%), whereas beans and potatoes were

the most affected.

In CAF, there were very little increases (<1% for all crops

except potato and beans, which were predicted a substantial

decrease).

Responses in SAF were observed positive only for cassava, millet,

and banana (5% each).

In SAH, responses were similar to those found in

WAF

In NAF, moderate negative impacts were predicted for beans (-4%), and potato (-4%), slight positive changes for millet and banana.63%

area with loss in suitability

9%area with gain in suitability

28%area without

changes

Cassava reacted very well to the predicted future climate conditions compared to other crops.

BEANS (-16%±8.8)POTATO (-14.7±8.2)BANANA (-2.5%±4.9)SORGHUM (-2.66%±6.45)

22.5

18.1

14.5

19.2

WhiteflyMealybugCassava mosaic diseaseCassava brown streak disease

-5.5-4.5

-1.5

-8600

1

0.25

0.42

Overall suitability changeCurrent climatically suitable area (million km2)

Area predicted to improve climate suitability (million km2)

24.0

19.1

15.1

20.5

2.1

1.8

0.8

1.7

Area likely to become pest and disease free (million km2)

Newly affectedregions (million km2)

Many cassava-growing regions (>80% of area) are not abiotically constrained in 2030, meaning that they are unlikely to bene�t from crop improvement for abiotic traits.

Increased drought tolerance could bring bene�ts to nearly 30% of cassava-growing regions in EAF, SAF, and SAH.

Cold tolerance is also a priority despite the projected warmer climates. This is largely because of constraints in high-elevation regions of EAF or in low latitudinal regions in SAF where seasonal temperatures during winter pose a constraint for cassava development.

Designed by Carlos Navarro-Racines (CIAT-CCAFS 2013) e-mail:c.e.navarro@cgiar.org

IS CASSAVA THE ANSWER TO AFRICAN CLIMATE CHANGE ADAPTATION?Research Area on Decision and Policy Analysis (DAPA)