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The Impacts of Climate Change on Gardens in the UK

Volume 3 Number 9 - December 2002
R. Bisgrove and P. Hadley (extracted from report)

A report "Gardening in the Global Greenhouse: The Impacts of Climate Change on Gardens in the UK" was commissioned by the National Trust and the Royal Horticultural Society in partnership with the U.K. Government Department for Environment, Food and Rural Affairs (DEFRA), Anglian Water, English Heritage, the Forestry Commission, Notcutts Nurseries, the Royal Botanic Gardens Kew and the UK Climate Impacts Programme.

The report examines the potential impacts of the expected climate changes on gardens in the UK.

In April 2000 the National Trust, the Royal Horticultural Society (RHS) and the UK Climate Impacts Programme (UKCIP) invited other horticultural and conservation groups to a workshop to raise awareness industry-wide and seek co-sponsorship for a research programme. The result was to commission a desk top study, ‘Gardening in the Global Greenhouse: The Impacts of Climate Change on Gardens in the UK’ to collate and assess all the available information on climate change and gardens, drawing on the latest set of UKCIP climate change scenarios published by DEFRA in April 2002.

The National Trust is a U.K, non-government organisation which looks after places of historic interest and natural beauty for the enjoyment of the nation. It owns and manages 248,000 hectares of land, as well as 600 miles of coastline. It cares for over 200 gardens, which together constitute the world’s largest collection of historic gardens and cultivated plants. The Trust has been monitoring and evaluating the projections of climate change in the UK for the past decade, so that it is able to respond to the serious change that the natural and historic environment is undergoing – including rising sea levels, soil erosion, damage to archaeology and historic buildings, and changes in plant and animal life.

The Royal Horticultural Society is a British gardening charity which encourages gardening through its publications, trials, lectures, education programmes and scientific research. It is renowned for its gardens and flower shows and is a source of advice and information for all gardeners.

Potential Impacts of Climate Change

In the preface the report identifies three interrelated phenomena in reviewing the potential impacts of climate change on gardens. The first is climate change itself. The second is the occurrence of extreme weather events such as floods and droughts and the third is human activity.

The climatic changes expected in the UK are described in the report Climate Change Scenarios for the United Kingdom: The UKCIPO2 Scientific Report (Hulme et al., 2002). Climate change is expected to increase the frequency of some extreme weather events, but predictions of such events are less certain than those for average changes in climate. Predictions of gale frequency in future are particularly uncertain. The Earth’s surface has changed dramatically as a result of human activity, some of which are root causes of climate change. Others serve to intensify the impacts of climate change or to bring them to wider notice, such as building houses in floodplains increases the risk and cost of flood damage by orders of magnitude and moving around the globe results in the spread of pests and diseases, of plants and of humans, to new areas so it is often impossible to say if changes in disease incidence are the results of climate change or of human activity.

Scope of the Report

The report assesses the physiological basis of plant responses to the changes which might be caused by climate change by examining plant responses to the increase of carbon dioxide and temperature and changes in water supplies and in pest, disease and weed incidence. It examines how plants in natural and managed communities and heritage gardens will respond to climate change.

The report then assesses the importance of management of gardens in a changing climate. It examines the climate change impacts on:

• particular soils;
• water (water supplies, water features, water management);
• trees (tree selection, fruit trees and bushes and tree management);
• shrubs (choice of shrub and sub-shrubs and their management);
• herbaceous perennials;
• bulbs;
• annuals and tender perennials;
• lawns and other grassy areas (diversity of grass areas, climate change impacts on the growth of grass and grass management);
• paths, walls, garden buildings and garden structures;
• garden staff (perceptions of climate change by garden mangers and responses of garden staff);
• garden visitors (impacts of climate change on garden visitors and the impact of  visitors on gardens in a changing climate).

Conclusions

Garden management in a warmer world will present a range of challenges and opportunities.

The impact of climate change in the UK is likely to lead to reduced frosts; an earlier spring, higher average temperatures all year round, increased winter rainfall, leading to risk from flooding and hotter, drier summers, increasing risk of drought.

In the UK, in the next 50 to 80 years, will be the British lawn will be particularly effected which could become increasingly difficult and costly to maintain and some traditional garden features may have to be replaced by new ones, more suited to changing conditions. For the heritage sector, the greatest challenge will be the long-term care of historic layouts, plant collections and planting effects, originally developed in climatic conditions that no longer exist.

However, botanic gardens have had to be intensively managed in order to grow the widest possible range of plants in the living collections. In gardens, plants grow in very favourable conditions. They are usually propagated in controlled conditions, planted into carefully prepared ground and protected from pest and diseases and competing plants. Thus the elasticity of response to climate change is very much greater than in nature.

The ethos and skills to deal with the management challenges (including the potential challenges associated with climate change) already exist. The factors important in determining climate change impacts will be hardiness and water availability and there may be additional costs such as irrigation. There will also be the advantage for many botanic gardens in being able to grow a wider range of plants. Climate change may offer new opportunities to develop the collections. Botanic gardens are in a key position to advance and disseminate knowledge on climate change and its effects.


Editor’s Note: This report is taken from:
Bisgrove, R. and Hadley, P., 2002 Gardening in the Global Greenhouse: The Impacts of Climate Change on Gardens in the UK. Technical Report, UKCIP, Oxford.

Copies of the report are available from:
The UK Climate Impacts Programme,
Union House
12-16 St Michael’s Street
Oxford, OX1 2DU, U.K.
Tel: +44 01865 432076
Fax: 01865 432077
E-mail: enquiries@ukcip.org.uk
Internet: www.ukcip.org.uk

The report or the Executive summary can be downloaded from the main partner websites: www.rhs.org.uk, www.nationaltrust.org.uk



The United Nations Framework Convention on Climate Change

This Convention addresses the concern that human activities have increased in the average temperature of the earth's surface and thus changed the basic conditions that have allowed life to exist on earth.

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