Impacts of climate on tropical crop production

Tom Osbornea

Andy Challinora,b, Tim Wheelerb, Julia Slingoa

a Department of Meteorologyb Department. of Agriculture

Crops and Climate Group

General Large Area Model for annual crops (GLAM; Challinor et al, 2004)

• Aims to combine:– the benefits of more empirical approaches (low input data requirements, validity

over large spatial scales) with– the benefits of the process-based approach (e.g. the potential to capture intra-

seasonal variability, and so cope with changing climates)

• Yield Gap Parameter to account for the impact of differing nutrient levels, pests, diseases, non-optimal management etc.

general circulation model

crop model

Forced with observed weather

400

450

500

550

600

650

700

750

800

850

900

1965 1970 1975 1980 1985 1990

Year

Yie

ld (

kg h

a-1

)

Model results

Observed yield(detrended to 1966 levels)

Impact of extremes: rainfall distribution

1975Total rainfall: 394mmModel: 1059 kg/haObs: 1360 kg/ha

1981Total rainfall 389mmModel: 844 kg/haObs: 901 kg/ha

Impacts of extremes - temperature

20 25 30 35 40 45

Tmax from -5d to anthesis (oC)

0

10

20

30

40

Nu

mb

er o

f g

rain

s p

er e

ar

a

Wheat crops grown at 350 ppm CO2

cd

20 25 30 35 40 45

Tmax from -5d to anthesis (oC)

0

10

20

30

40

Nu

mb

er o

f g

rain

s p

er e

ar

a

Wheat crops grown at 350 ppm CO2

cd

Also observed for rice (above) and groundnut

Anthesis ~ time of flowering

Modelling high temperature stress

• Determine a flowering distribution

• Calculate impact of each high temp episode (this is a sum over all yield-determining flowers).

• The most severe high temperature episode impacts the harvest index. • Simulate tolerance by choice of HTS parameters. Perhaps simulate

escape by altering the flowering distribution in response to stress.

Importance of adaptation

Number of years from period 2071-2100 when the total number of pods setting is below 50%.

Sensitive crop variety Tolerant crop variety

How do we intend to link to EPS?

• Use the climate model projections directly.

What are our main questions requiring discussion in this meeting?

• How to get hold of the EPS output – password does not work? AJC

What have we achieved so far?

• Incorporated effects of high temperature stress at flowering on yield and represented response to stress of different crop varieties.

Q & A

Which WP6.2 tasks etc will we contribute to and when?

• Milestone 6.14: Completion of preliminary probabilistic assessments of climate change impacts using calibrated impact models

Due Feb 2008

• Task 6.2.10: Preliminary evaluation of the impacts of extreme events … for crops … from available climate projections

Ongoing

• Task 6.2.11: Application of preliminary results from the EPS to impact models for estimating risks of extremes and risks of impacts.

Ongoing

(2 months unfunded)