With a summer of flooding behind us and potentially heavy winter rains to come, it's worth asking what Dulwich can do to protect itself against climate change. As residents of the village and surrounding roads will recall, flash floods are not exactly an unknown phenomenon in SE21.

Some of the answers are obvious, some less so. Most carry unexpected spin-offs, usually beneficial. Halting, or reversing, the paving-over of front gardens, for example, will slow down water speeds, holding up rainfall in soil and vegetation. It will also make for greener streets, good both visually and for wildlife - and for property prices too.

The bigger the expanse of greenery, the greater this effect. Trees are highly efficient in this respect, since their leaf area is usually many times greater than the area of ground they cover. But the more vegetation there is above ground level - bushes, shrubs, hedges - the slower the rainfall will rush off into the streets. From this perspective, "designer" gardens - full of stonework, decking or elegant but non-permeable statuary - are among the best ways of encouraging a flood. Turney Road, where paving-over has been at epidemic levels, was noticeably badly affected in the last Dulwich tsunami.

One of the keys to flood control is porous or permeable surfaces - which usually means natural ones. Hence the value of grassed and vegetated green space, with which Dulwich is well-supplied - at present (more on this below). Areas with "swales" - indentations in the surface - are better than flat ground, so impromptu wetlands in, say, Dulwich park are a sign that the park is performing a valuable flood-control function - even though it doesn't chime with some people's idea of tidiness.

Another method of preventing the overloading of drains is what is sometimes grandly known as rainwater harvesting. At its simplest, this means diverting your downpipes into a water butt (or butts) - relatively cheap and easy to do. If the butt overflow is directed into the garden you have your own continuous supply of (free) water for plants: you're also protecting yourself against building cracks and subsidence in times of drought. I know at least two people in Dovercourt Road (myself included) who have done this; a neighbour has even incorporated a rather elegant sprinkler system.

Moves such as these would come under the heading of "adaptation" or "mitigation". But we can also take preventative action that doesn't involve major challenges to lifestyles - cutting out carbon uses that are essentially peripheral, for example. These include many gadgets and products used in gardening and landscape maintenance. For smaller lawns and hedges, what's wrong with manual cutting devices? In parks, leaf-blowers and strimmers are an outdated, noisy and carbon-intensive concession to the neatness obsession. More and more studies are pinpointing pesticides as a threat to human health - not to mention the atmosphere (since fossil fuels are used to make them). A Dulwich without such items would be fitter, healthier, significantly quieter - and thus less stressful - as well as being far more climate-friendly. Even simpler, why not just garden or maintain less? Not only are "untidy" gardens better for biodiversity. More biomass means more carbon locked away in plants: each tree cut down, by contrast, is another pulse of carbon into the atmosphere.

But there are broader land-use issues. The biggest threat to Dulwich as a place is development and the loss of its semi-rural, village-like character. The causes of this are clear - the growth of population nationally and in London, increased wealth, the attraction of its schools, the lure of its environmental quality, the financial needs and objectives of the major local landowner (the Dulwich Estate). In one current case, at 37 College Road, virtually an entire garden is being replaced by a new executive-style house, with the loss of 20 trees, many of them mature - the estate taking the view that the size of the green space available presented, not a reason to preserve, but a unique opportunity to develop. The loss of the trees was described as unimportant on amenity grounds as many could, allegedly, not be seen from the road. But throughout SE21 and SE22 generally, incremental urbanisation, from designer gardens to infill and backland development, has seen the natural and the man-made increasingly in conflict - with the natural, usually, losing out. The increasing loss of trees to usually ill-founded subsidence claims is one of the most worrying symptoms of this.

Urban history is littered with examples of sought-after places that have been developed to death - the Bronx was once one of New York's greenest suburbs. Climate change is demonstrating that trees, shrubs and soft natural surfaces are more than mere amenity. Even if we don't value the quality of life they represent or the wildlife they sustain, they qualify, increasingly, as basic green infrastructure - a vital defensive commodity in a stormier and more extreme climate.

David Nicholson-Lord is a member of the wildlife and trees committees and of the executive of the Friends of Dulwich Park. He is an environmental writer, chairs the Urban Wildlife Network and is research associate for the Optimum Population Trust


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