Analysis: Proving the climate change case for trees

Arboricultural Association conference finds that new research will help focus minds on the role of trees

In two months' time, heads of governments across the world will meet in Copenhagen for a major climate-change summit to thrash out a successor to the Kyoto Protocol. Tensions could reach breaking point as the world's richest countries - already bruised by the recession - argue against bearing the economic brunt of helping to reduce emissions.

It is a pivotal time for the industry to lobby the UK Government about the issue of climate change and the solutions that horticulture can provide.

Some of the answers are right here within the industry, according to experts in green space, landscape architecture and arboriculture.

During the Arboricultural Association conference at the University of Exeter last week, the significant role of trees in adapting to climate change was one of the key points of debate.

Arguing that mitigating climate change is a practical impossibility and the focus must lie in adaptation, the Woodland Trust's head of conservation policy Mike Townsend explained: "It is a rather apocalyptic world view but we are failing to respond effectively or with any sense of real urgency.

"I would like to be optimistic about (the climate change talks in) Copenhagen but I struggle to see how governments will take the necessary steps. The subtext will be continued growth."

Adapting to climate change though green-infrastructure measures is a debate that has gained some ground this year, following the launch of CABE's Sustainable Cities programme and its Park City conference in the spring.

A public endorsement of the need to invest in green infrastructure by then housing minister Margaret Beckett was a short-lived coup for the sector after the MP was sacked in Gordon Brown's summer Cabinet reshuffle.

It is now up to the industry to keep up the pressure through highlighting credible - and financial - arguments for investment.

"If it is the purpose of government to safeguard its citizens then it has a duty to carry out adaptation measures," added Townsend. "It is difficult to understate the role of green infrastructure and the importance of trees in creating that green infrastructure."

Improving air quality - and thus health - could reduce healthcare costs, while trees could also assist in tackling problems of flooding and reduce energy consumption through their shading and cooling effects.

The health aspects could be of special interest to a government of any colour as it grapples with managing the costs of the NHS. Indeed, a project to plant 1.3 million new trees at NHS sites over the next five years launches on 6 October and is designed to "benefit people medically, socially and environmentally through the planting, maintenance and use of wooded areas".

The NHS Sustainable Development Unit is working with the Forestry Commission, the Woodland Trust, Natural England, Common Ground and BTCV to identify land where trees can grow.

According to Townsend, figures show that if one per cent of the 2.5 million on incapacity benefit could be encouraged back to work through improving their lifestyle it could save £67m a year.

The costs of cooling buildings and dealing with surface water flooding could also be tackled.

The University of Manchester's reader in ecology Dr Roland Ennos, who was involved with the college's groundbreaking research into the urban heat island effect, revealed a new project examining the effects of trees on flooding is to begin next week. "The problem is that [the arguments] don't influence politicians or planners until we actually have some numbers," he warned.

The only studies carried out so far have been modelling research, rather than looking at actual data, added Ennos. A team comprising Ennos, PhD student David Armson, Professor John Handley and Dr Susannah Gill is setting up a series of plots that will measure water run-off from sites covered in grass, tarmac or a combination of tarmac, soil and trees.

The project is being supported by the Engineering & Physical Sciences Research Council (EPSRC), Natural Environment Research Council (NERC) and Manchester's Red Rose Forest.

"This new set-up will investigate the effectiveness of trees at reducing urban flooding," added Ennos.

The resulting figures will provide a major source of pressure on planners and policy makers.

National Association of Tree Officers director Mike Volp has already argued for arboricultural input in every planning department. Chartered civil engineer John Young, of Edenvale Young Associates, agreed that recognition of trees in sustainable urban drainage (SUDS) planning was critical.

"There is a very powerful movement in places including New York and Kuwait looking at issues of flooding and trees," explained Young. "I'm not sure there's the same in the UK.

"With climate change we can expect more intense and frequent rainfall. The effects will be profound but there's a very good correlation between SUDS and trees. Arbs should be involved in design because unless you share your knowledge, we won't be able to get it into our schemes."

Specific data, such as water-retention rates of tree canopies, is needed to ensure that the benefits can be quantified and understood by planners and engineers, added Young. "At the moment we don't have the knowledge to incorporate trees formally so research is required and codes of practice must be developed to give engineers the tools."

Trees in Towns II author Mark Johnston added: "Arbs must seize this opportunity to promote the crucial importance of trees in green infrastructure and their own role as the specialists."

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