Global warming and the expansion of the built environment are expected to intensify the urban heat island effect and related adverse health impacts.

A new scientific study published in The Lancet and referred to in the Science for Environment Policy Newsletter of the European Commission Directorate-General for Environment shows that increasing tree coverage to 30% would lower temperatures by an average of 0.4°C, avoiding about 1.8% of all summer deaths in European cities and nearly 40% of deaths attributable to UHI effects.  

The heat-health impact assessment covers 93 European cities and estimates the mortality burden attributable to the urban heat island effect and the mortality that could be prevented by increasing the urban tree coverage. The cities most likely to benefit from the increase in tree coverage are in south and eastern Europe, where summer temperatures are highest and tree coverage tends to be lower.