Presentation made in the Global Cassava Partnership meeting in Kampala, Uganda 18th June 2012.

1. Climate change and the outlook for Cassava
Julian Ramirez, Andy Jarvis, Patricia
Moreno, James Cock, Carlos Navarro,
Beatriz Herrera

2. What will be the role of cassava in a
climate changed world?
• We know cassava is a resistant crop….
• …..but will it stand up to climate change?
• How does it fair up with other major staples?
• What are the research challenges over the
coming decades?
• What has all this got to do with film stars?

3. Nothing new!

4. A bright future for cassava?

5. Cassava – an exception to the rule?
•For example, US maize, soy, cotton yields fall rapidly when exposed
to temperatures >30˚C
•In many cases, roughly 6-10% yield loss per degree
Schlenker and Roberts 2009 PNAS

6. How might the climate change?

7. What will this mean for cassava?
Minimum absolute
300
rainfall (mm)
Minimum optimum
800
rainfall (mm)
Maximum optimum
2200
rainfall (mm)
Maximum absolute
2800
rainfall (mm)
Killing temperature (°C) 0
Minimum absolute
15.0
temperature (°C)
Minimum optimum
It evaluates on monthly basis if there 22.0
temperature (°C)
are adequate climatic conditions Maximum optimum
32.0
temperature (°C)
within a growing season for Maximum absolute
temperature and precipitation… 45.0
temperature (°C)
…and calculates the climatic suitability of the Growing season (days) 240
resulting interaction between rainfall and
temperature…

8. Current suitability

9. Current climatic constraint

10. Future suitability change

11. What will this mean for cassava?

12. The Rambo root!

13. But what about other staples?
The Rambo root versus Mr. Bean

14. Cassava suitability change compared
with other staples
• Cassava consistently outperforms other
staples in terms of changes in suitability

15. Cassava’s role as a substitution crop
• Cassava as a fallback crop under an uncertain
climate (risk management)
• Cassava as the substitution crop for other
staples more sensitive to heat and drought
• Cassava as a source of increasing food and
nutritional security across the continent

16. Not so fast….
• Pests and diseases:
the Achilles Heal of
cassava?

17. Impacts on mealy bug and brown
streak virus
Mealy bug Brown streak virus

18. Future Priorities
• The Achilles heal: addressing pest and disease
susceptibility
• Breeding in low latitudes for cold tolerance
(e.g. Southern Africa, Brazil, China)
• Improving cassava science and knowledge:
physiological models of the crop and its
diseases

19. Look for conditions in future analogues to existing
conditions how cassava will perform
Simulate crop growth and development within and
beyond the current climate range where cassava is
currently grown

20. AgTrials.org (929 cassava trials)
Calibrate and evaluate
the model using multi-
site trial data
We need
more!

21. It will be developed from the Mathews & Hunt GUMCAS model
It appears to be the most complete cassava model currently
available and also it is in DSSAT requires more development
and calibration
• Improve the DSSAT GUMCAS model with (so far):
• DSSAT team (Gerrit Hoogenboom (WSU), Cheryl Porter,
K. Boote, and J. Jones (University of Florida))
• CLAYUCA and partners
• The Thai cassava modeling group (Dept of Agriculture,
Khon Kaen University and Chiang Mai University)
• Researchers involved in developing the early cassava
models (e.g. Tony Hunt, James Cock).

22. • Information of such aspects as the effects of elevated CO2 levels on
growth and development.
• Trials by researchers valuable information for development and
calibrate the model.
• Information on a farm level realistic simulation of the crop
considering yield gap
• The creation of an inter-agency cassava model that evaluates a
variety of scenarios with respect to cassava productivity
• Members can use the models directly, or request specific analysis

23. Email: a.jarvis@cgiar.org
Internet: http://dapa.ciat.cgiar.org
http://www.ccafs.cgiar.org
• (Jarvis et al.,2012) Is cassava the answer to African climate change adaptation
• (Ceballos et al., 2011) Chapter 19. Adaptation of Cassava to Changing Climates.
• (Herrera et al., 2011) Threats to cassava production: known and potential geographic
distribution of four key biotic constraints