1. Climate change and water resources in Europe Professor Nigel Arnell
EU Water Directors Meeting
London, 28-29th November 2005
Climate change and
water resources in
Europe
Professor Nigel Arnell
School of Geography
University of Southampton

2. Outline Climate change: trends and projections
Implications for river flows and water resources
Implications for adaptation and water policy

3. Temperature change
The last 150 years

4. The future Future climate change depends on (i) future emissions
(ii) what happens to gases
(iii) sensitivity of climate to change

5. Change in temperature 2020s: 0.8 to 0.94oC higher than 1961-1990

6. Change in precipitation
Shift in regional patterns
Change in seasonality

7. Effects on runoff and recharge
Annual runoff
Change by 2020s
A2 emissions
The pattern is very similar for drought runoff

8. Trajectories of change
Dotted lines indicate decadal variability: this can be added to or subtracted from climate change trend

9. Changes in timing of flows
Higher temperatures result in changes in the seasonal distribution of flows in some regions where winter precipitation currently falls as snow

10. Pressures on water resources
Resources per capita by 2021
Increases in demand place resources under pressure in many basins

11. What effect does climate change have?
Basins with < 1700 m3/capita/year
Net increase in stress
Abstract measure of water resources stress

12. What effect does climate change have?
2021, no climate change, A2 world:
365.6 million people living in watersheds with
< 1700 m3/capita/year

13. Specific water resources impacts…
Severn-Trent 6.5% reduction by 2025
Thames / London % reduction by 2025

14. Certainties and uncertainties
“Climate change is uncertain: we don’t know what will happen over the next few decades”
“We can’t predict future energy use”
“We can’t predict future weather or climate”
but….
We KNOW climate will change
We KNOW we cannot rely on past climatic data
We KNOW to expect surprises

15. Implications for adaptation
Capacity-building and specific actions
Capacity-building
- conceptual change
- development of procedures / tools
- development of intellectual capacity
Specific actions
- measures to meet adaptation target (e.g. maintain supply-demand balance)
- supply-side / demand-side

16. What are the limits to adaptation?
Physical limits
- change is so great that the impacted system is destroyed
- change is so great that it is physically impossible to reduce loss
Financial limits
- it is too expensive to respond to the impact
Feasibility limits
- social and political constraints on options
ADAPTATION
iv. Capacity limits
- limited institutional capacity to make adaptation decisions

17. Enhancing the knowledge base
Enhanced climate scenarios (extremes/variability)
Moving beyond water quantity: water quality and land use effects
Developing “best practice” assessment methodologies (and incorporating into water policy)
Developing flexible adaptation measures
- understanding consumer behaviour

18. Conclusions Climate change is happening
Climate policy will have little effect over the next few decades
We will see significant changes in water resources
We need now to incorporate climate change into strategies and plans