Gardening in the Global Greenhouse: The Impacts of Climate Change on Gardens in the UK

1. Gardening in the Global Greenhouse: The Impacts of Climate Change on Gardens in the UK Richard Bisgrove and Paul Hadley,Centre for Horticulture and Landscape The University of Reading

2. The brief • To apply the UKCIP02 scenarios to gardens and allied industries. Long term trends in climate change. Extreme weather events (Land use changes)

3. Annual and Seasonal Temperatures with Medium/High Emissions

4. Carbon dioxide concentrations will rise • Affects plants directly through photosynthesis • Plants will grow more rapidly. • Plants will be sturdier. • …..but will need more work to control excess growth.

5. Temperatures will rise • Earlier springs, later autumns and longer growing seasons. • More hot and very hot summer days. • Much less frost and frost damage – except possibly in autumn. • Reduced winter chilling • Increased loss of soil carbon • Increased evaporation

6. Summer rainfall will decrease • More frequent and prolonged droughts. • The main casualties will be the UK lawn, large trees - especially beech - and many herbaceous perennials. • Hotter, drier conditions will favour pests such as spider mite, aphids and allow the spread of exotic pests. • The iconic image of the UK as a green and pleasant land is under serious threat.

7. Autumn and spring rainfall will also decrease • Conditions for gardening and garden visiting will improve. • Earlier displays of bulbs and other spring flowers, and brighter autumn colour. • Conservation of water will become increasingly important. • Return of autumn as the main planting season? • Nurseries might capitalise on the ending of summer drought as a stimulus for gardening

8. Winter rainfall will increase ...BUT evaporation will also increase. • Lower soil moisture reserves in much of the country. • Potential for a more Mediterranean garden flora. • ….but the winter light climate will not be Mediterranean. • Wetter and warmer winters will favour the spread of root fungi, and may increase damage from waterlogging.

9. Winter rainfall will be increasingly concentrated into heavy downpours • Flood risks are increased. • The need for water conservation measures become more important. • (Intense precipitation events become less common in summer).

10. Wind speeds are not expected to increase significantly as a result of climate change • But small increase in wind speed may result in large increases in wind-throw especially as trees become larger

11. Sea level will rise • Combined with windier conditions in winter this will result in significant increases in storm water surges and a dramatic increase in flooding of coastal sites

12. Overall Impacts: • Increased opportunities for adventurous gardening in the small, private garden. • Increased difficulties for the conservation of historically important gardens and plant collections. • Increased opportunities for nurserymen to enlarge the UK plant palette and perhaps to extend the garden season. • Increased challenges for the water supply industry to meet and manage the demand for water by gardeners.

13. Overall message....... • Climate change is here and here to stay. • Adverse effects of climate change are exacerbated by land use intensification. • We can develop some resilience to climate change by good gardening. • Gardens have an important part to play in the UK psyche • ….and in reversing the adverse effects of development. • By extending the principle of good gardening in the UK landscape as a whole we can retain the reality and the perception of the UK as a green and pleasant land