Climate change

The serious impacts of our fast changing climate are a big global cause for concern among scientific, political and environmental groups but what exactly are the consequences for UK horticulture and gardening? The RHS takes a look.

Our changing climate means severe alterations to what we grow and how we grow it, and it is clear that our gardens will become an increasingly important resource for ourselves and wildlife. There is still much need for a basic understanding of what the future holds and though no-one has all the answers yet, gardens and growing plants can be a potentially important factor.

Global warming is here and the rate of change is accelerating. The scientific community informs us it is primarily a product of mans use of fossil fuels. So what will it mean to gardens in the global greenhouse?

The UK Climate Impacts Programme (UKCIP), along with involvement from the RHS, published a report in November 2002 called Gardening in the Global Greenhouse. In the five years since its publication, climate change has risen in the political agenda and become an almost daily news item.

Our changing climate

So what is the difference between climate and weather? Weather is what happens every day, while climate is the long-term average of weather conditions. It is important to realise that weather, climate and climate change are complicated subjects that interact in extremely complex ways with many other factors.

Urbanisation of landscape, increased human mobility, sea-level rise, higher temperatures, warmer snow-free conditions and increased release of methane (a gas with a much more powerful greenhouse effect than carbon dioxide) are just some of the elements skimming the surface of changes to our natural world. Climate scientists are constantly refining their predictions as these elements are ever changing.

Impacts on gardens

Gardens are unique ecosystems, combining many different plants and materials such as water, wood and concrete. In gardens, plants are much more adaptable to climate change than those in natural and semi-natural ecosystems, where the fight for survival is fierce.

The average effect of climate change will be that summers will be hotter and drier. Lawns will turn brown, bedding plants and vegetables will require more water, trees may scorch and lose their leaves prematurely and hosepipe bans may be more widespread.

Winters will be increasingly mild: less frost, much less snow, but more rain and in heavier downpours. Spring will come earlier (currently, it is arriving two to six days sooner per decade) and summer will extend longer into what would have been autumn (currently, two days later per decade). Clear autumn skies should result in brighter autumn colours - if the leaves have not already crisped and fallen due to water stress. These changes will be even more marked in the wider landscape than in gardens.

What can we do?

In general terms there are many things that we can do in our gardens, especially now that the world is beginning to wake up to the reality of climate change. The UK Government has committed itself to reducing greenhouse gas emissions by 60 percent by 2050 - but it is yet to spell out how it plans to achieve this.

Gardeners cannot save the world but they can lead by example with the good practices needed to adapt to, mitigate and eventually help to halt global warming.

The RHS enlisted the advice of Senior Lecturer in Landscape Management at the University of Reading, Richard Bisgrove, on what gardeners can do to minimise their carbon footprint in an effort to garden more sustainably, (see list below).

Ways to help

• Be adventurous with new plants and ideas.
• Provide more shade for summer, using pergolas etc, so that you can continue to enjoy the garden when it is too hot to work in it. If plants succumb to recurrent droughts or new pests, simply try growing something else.
• Grasses and perennials in gravel is both drought tolerant and low maintenance
• Be flexible and adaptable, and try to avoid problems rather than control them. Keep the garden in a vigorous condition with a diverse range of youthful plants to help guard against disaster, so if one plant fails the gap is easily filled
• Most of the effects of climate change in UK gardens in the 21st century should be manageable. We have an excellent infrastructure, from fire brigades to insurance policies, to support us in what are predicted to be more extreme events, such as floods and storms.
• Be greener: store rain water for use in dry weather, and store carbon inside plants and in the soil.
• Organic and permeable materials are better for paving than concrete, which causes large amounts of carbon to be emitted into the atmosphere in its manufacture and transport, and offers nothing in return.
• Deep cultivation of the soil to add organic matter, organic mulching and growing woody plants all help to remove carbon dioxide from the atmosphere
• Think sustainable when buying gardening tools and working in the garden. Sharpen the shears, abandon the powered hedge-trimmer, and invest in a hand-propelled mower.