Climate change and the outlook for Cassava

Julian Ramirez, Andy Jarvis, Patricia Moreno, James Cock, Carlos Navarro,

Beatriz Herrera

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?

Nothing new!

A bright future for cassava?

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

How might the climate change?

It evaluates on 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…

What will this mean for cassava?

Growing season (days) 240

Killing temperature (°C) 0

Minimum absolute temperature (°C)

15.0

Minimum optimum temperature (°C)

22.0

Maximum optimum temperature (°C)

32.0

Maximum absolute temperature (°C)

45.0

Minimum absolute rainfall (mm)

300

Minimum optimum rainfall (mm)

800

Maximum optimum rainfall (mm)

2200

Maximum absolute rainfall (mm)

2800

Current suitability

Current climatic constraint

Future suitability change

What will this mean for cassava?

The Rambo root!

But what about other staples?

The Rambo root versus Mr. Bean

Cassava suitability change compared with other staples

• Cassava consistently outperforms other staples in terms of changes in suitability

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

Not so fast….

• Pests and diseases: the Achilles Heal of cassava?

Impacts on mealy bug and brown streak virus

Mealy bug Brown streak virus

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

Look for conditions in future analogues to existing conditions how cassava will perform

Improve existing estimates of climate change impacts on cassava and set up breeding priorities for climate change

adaptation

Create a reputable cassava process-based model with all key components

IMPROVING KNOWLEDGE: OUR WORKPLAN

Simulate crop growth and development within and beyond the current climate range where cassava is

currently grown

AgTrials.org (929 cassava trials)Calibrate and evaluate the model using multi-site trial data

We need more!

TOWARDS A MECHANISTIC MODEL

• 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).

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

AN INVITATION TO PARTICIPATE: A LOOSE CONSORTIUM

• 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

Why a consortium???

Outputs

• 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

• (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

Email: a.jarvis@cgiar.orgInternet: http://dapa.ciat.cgiar.org

http://www.ccafs.cgiar.org