1) European annual mean air temperatures have increased by over 1 degree Celsius since 1860, with the 1990s being the warmest decade on record. 2) Climate variability impacts irrigation water demand, with demand driven by changes in rainfall patterns and evapotranspiration rates. 3) Future climate changes are expected to significantly increase irrigation needs across much of England by the 2050s due to rising temperatures and changing rainfall patterns. This poses risks to irrigated agriculture.

1. Adapting to a changing climate
Jerry Knox, Centre for Water Science

2. Observed increase in European annual mean air temperature, 1860 to 2008
2.00
1.75 2008 10th warmest on record
e 1.50
g
a
r
e 1.25 1990s warmest decade
v
a in last 100 years
9 1.00
9
8
1
-
0 0.75
5
8
1 0.50
o
t
d 0.25
e
r )
a C
p 0.00
mo
o (
c -0.25
,
n
o
i
t
a
i -0.50
v
e -0.75
d
e
r
u
t -1.00
a
r
e
p -1.25
m
e
T -1.50
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2
8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 0
5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Annual deviations (land only)
10-year moving average (land only)

4. Impact pathways for irrigated agriculture
Human activity
Increase in Stomatal resistance Crop cultivars
atmospheric CO2 Crop growth rates Areas irrigated
concentration Depths applied
Climate and
weather
Changes in rainfall Irrigation water
and ET (pattern and demand
intensity)

5. Climate variability drives irrigation water demand
100
Evapotranspiration (ET)
90
80
70
60
50
40 Rainfall (P)
30
20
10
0
l
n b ar pr ay n Ju ug p ct ov ec
Ja Fe M A M Ju A Se O N D

6. Predicted changes in rainfall
2050L 2050H
60
40
Precipitation anomaly (%) .
20
0
-20
-40
-60
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

7. Predicted changes in evapotranspiration (ET)

8. Current agroclimate
variability (1961-90)
Supplemental irrigation
concentrated in east and
south east England – where
rainfall <600 mm year

9. A changing climate (2020s)
By the 2020s, the irrigation
needs of central England will
be similar to those experienced
now in eastern England

10. A changing climate (2050s)
By the 2050s, eastern
southern and central England
will have irrigation needs
greater than those currently
experienced anywhere in
England

11. Case study – impacts of climate change
on potatoes in the 2050s
 Maris piper variety for pre-pack market
 Sandy loam soil
 Overhead irrigation
 Scheduled for scab control and bulking
Impacts on water use and yield

12. Impacts on future irrigation needs (mm)
400
Baseline
350 2050_L
2050_H
300
Irrigaiton need (mm)
250
200
150
100
50
0
3 8 14 19 24 30 35 41 46 51 57 62 68 73 78 84 89 95 100
Probability of non exceedance (%)

13. Impacts on future irrigation needs (mm)
400
Baseline
1. Future ‘average year’ more like a current
350 2050_L ‘dry year’
2. Irrigation schemes could fail to meet future
2050_H
peak irrigation demand in 50% of years
300
Irrigaiton need (mm)
250
200
150
100
50
0
3 8 14 19 24 30 35 41 46 51 57 62 68 73 78 84 89 95 100
Probability of non exceedance (%)

14. Uncertainty in future irrigation needs

15. Climate impacts on potato yield

17. The adaption message
 Water is already scarce, and climate change will make it even scarcer
 Adaptation will be essential, and will reinforce current trends
 Many adaptations actions will be “no regret”
i.e. they make sense now by solving existing water resource issues,
and contribute to your future adaptability
Beware of mal-adaptations - changes that climate change renders
worthless

18. Crop level adaptation
Modelling assumed unchanged practices - but there will be autonomous
adaptation even if not planned adaptation
 Earlier planting and harvest dates
 Change to better adapted varieties
 Less use of very light soils
 Move to different region – northwards and westwards
 GM technology

19. Adaption – what others are doing
Building reservoirs
Starting to work together
forming ‘water abstractor groups’
Making better use of existing supplies