1. Impact of climate change on agriculture An overview!
Rosemary Collier
Warwick Crop Centre, School of Life Sciences

2. General effects of climate change
Changes in mean temperature
Changes in amounts and pattern of rainfall
Increases in the number of extreme events
Increase in atmospheric CO2 and ozone
Most of these will vary by region

3. Weather versus climate
According to the United Kingdom Met Office:
weather is defined as the temperature, precipitation and wind which changes hour-by-hour and day-by-day,
climate is the average weather we expect over a long period of time.
Whilst farmers are interested in climate change – their daily battle is with the weather! 

4. ©William Morfoot Ltd
©Oklahoma Farm Report
©James Ravilious

5. Farmers (and their customers) would appreciate better long-term weather forecasting!

6. Changes in mean temperature (increases)
Longer growing seasons in temperate countries
Faster plant growth in many cases – earlier harvest – e.g. cereals, lettuce
Less risk of frost damage
Could grow ‘new’ crops e.g. vines, apricots, sweetcorn, sunflowers, quinoa
Warmer weather may adversely affect crops that have ‘chill’ requirement e.g. apples, cauliflower

7. Changes in mean temperature (increases) – pests and diseases
Insect development generally faster at higher temperatures
Insect survival may be greater in warmer winters
Warmer winters may favour survival of diseases
Species have ‘optimum’ temperature ranges

8. Changes in amounts and pattern of rainfall
Less rain will lead to water stress and increase the requirement for irrigation on certain crops
Less rain may affect quality – either positively or negatively
Adaptation/opportunities??

9. Changes in amounts and pattern of rainfall
Some pests prefer dry conditions
Some prefer wet conditions e.g. slugs
Fungal diseases require high humidity
Adaptation/opportunities??

10. Increases in the number of extreme events
Flooding can have impacts on crop growth, crop quality
Can also have effects on access to the land – planting, harvesting
Can affect soil and water ‘quality’
through erosion
Adaptation/opportunities??

11. Increases in the number of extreme events
Storms can cause crop damage
Winds and floods can help pests and diseases to disperse
Adaptation/opportunities??

12. Increase in atmospheric CO2 and ozone
Increased CO2 may increase photosynthesis and improve efficiency of water use.
May increase crop yield provided that other essential resources are not limiting.
Ability of crops to benefit also depends on crop genotype (cultivar) and management.
Increase in ozone levels may damage plants.

13. Effect on species ranges
Plants and animals arrive on imported items or under own own steam
Climate change may make conditions more suitable for exotic species - which could be pests or could affect our native flora or fauna adversely
Likely that some native plant and animal species will move ‘northwards’ over time

14. How do we try and predict the effects of climate change on agriculture?
Climate scenarios e.g. UKCP09
Mathematical models of plant growth, pests, disease etc
Use simulated weather data from scenarios as input for the models

16. Conclusions
Over time, climate change is likely to have some positive - and some negative - effects
Uncertainty is obviously key issue - as is variability
There are opportunities for exploitation/adaptation
There is still a lot we don’t know!