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

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

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! 

©William Morfoot Ltd ©Oklahoma Farm Report ©James Ravilious

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

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

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

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??

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??

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??

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

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.

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

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

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!