Why trees: Climate change

Trees and woods can help to improve the quality of our air, cool our warming plant, reduce the risk of flooding as well as function as an excellent store of carbon.

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Trees and urban greening play a key role in:

  • Reducing harmful pollutants in the air – Trees can help to reduce harmful pollutants, which are deposited into the atmosphere by industry and transport. Doubling tree cover could reduce the concentration of fine PM10 particles by 25% (1)
  • Cutting cooling costs and air pollution – Urban trees reduce heat and air conditioning costs of building, in turn saving as much as 10% on annual energy consumption and cutting down air pollution caused by burning fossil fuels (2)
  • Cooling our cities and towns – Trees lose moisture from their leaves and, coupled with the shade they cast and the heat reflected upwards from their leaves, significantly reduce summer temperature in towns (3)
  • Reducing the risk of flooding – Trees reduce surface water runoff, which can overload drainage systems, and lead to flash flooding by around 60% compared with asphalt (4)
  • Carbon – Co2 is released into the air primarily by burning fossil fuels. One of the key ways in which carbon can be ‘locked up’ is by trees and forests, which store up to 25% of the world’s carbon (5). UK forests and woodlands act as a carbon sink and remove about 10 million tonnes of carbon from the atmosphere every year

 

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References

  1. Bradshaw AD, Hunt B & Walmsley T (1995) Trees in the Urban Landscape; Principles and Practice, E & F N Spon;
  2. Heisler GM (1986) Energy Savings with Trees, Journal of Arboriculture, 12 (5)
  3. Huang YJ, Akbari H, Taha H & Rosenfeld AH (1987) The Potential of Vegetation in Reducing Summer Cooling Loads in Residential Buildings, Journal of Climate and Applied Meteorology 26 (9) : 1103 – 1116
  4. The Effect of Trees and Grass on the Thermal and Hydrological Performance of an Urban Area (2012) PhD thesis for The University of Manchester; David Armson
  5. Forestry Commission: Carbon Trees, and Forests at http://www.forestry.gov.uk/forestry/infd-7m8fa6; 18th December 2014
  6. Forestry Commission: Forestry and climate change (2000)