ONE of the beneficial side effects of the 1996 Olympics was what has become known locally as the "Re greening of Atlanta". It was undertaken in response to the startling observation in the early 1990s that the average summer temperature of that city had increased by a full 4C in 20 years, and by an even greater amount in some of its more densely populated areas. It was calculated, moreover, that this rise in temperature had increased summer pollution levels by about 30 per cent. Further investigation revealed that during the period in question Atlanta had lost two thirds of its "urban forest", and that this was almost certainly responsible for the observed enhancement of the summer "heat island" effect.
Spurred on by the activity engendered by the approaching Olympics, the citizens of Atlanta resolved to ease the problem by a massive but well focused programme of tree planting. It was reckoned that the shade from trees placed in strategic positions beside many of the city's buildings would reduce the amount of heat absorbed by the structures. Moreover, the energy required to evaporate water from their leaves would reduce the temperature of the general environment, and the trees would also provide a form of air conditioning as the city air wafted through their cool foliage. A bonus was anticipated from the fact that trees absorb and store moisture, so the efficiency of the city's drainage system in coping with heavy thundery downpours would be improved.
Here in Ireland, South Dublin County Council has recently been doing its bit to add to Dublin's urban forest, and at the same time has managed to mark the sesquicentenary of the Great Famine in a most singular way. The Famine Commemorative Arboretum in Corkagh Park, Clondalkin, is a carefully designed plantation comprising 150 varieties of trees, one for each year since that event. The trees themselves are planted in a design of rays of sunshine, radiating outwards from a "sun" of five Irish sessile oaks, representing Ireland. The five "sunbeams", as it were, represent the five continents to which survivors emigrated, and each is planted with species indigenous to its continent of inspiration. The grass covering the space between these arboreal continents and the Irish oaks represents the oceans over which our ancestors travelled on their journey to their adoptive homelands.
The arboretum will ultimately have a population of about 2,000. Any individual may sponsor a commemorative tree by sending £20 to the Tree Council of Ireland at the Royal Hospital, Kilmainham, and will be issued with a formal certificate to identify the foster tree.