Heat waves are a known hazard. Death rates rise whenever cities experience unusually high summer temperatures, and the CDC estimates around 600 deaths in the US annually are attributed to heat as a primary or secondary cause. The 2003 European heat wave resulted in more than 70,000 deaths and heat waves kill more people in Australia than any other natural hazard. With climate change expected to increase the warmer seasonal length and average high temperatures, researchers have begun seeking solutions that will target the problem in cities, where the urban heat island effect already raises temperatures higher in cities than surrounding suburban regions.
A new study titled "Urban Vegetation for Reducing Heat Related Mortality" released this year by the Commonwealth Scientific and Industrial Research Organisation in Australia shows that added vegetation in urban areas significantly lowers neighborhood temperatures, which in turn reduces the dangers of heat waves. By using a meso-scale climate model to asses the impact of urban vegetation on temperature in ten different urban vegetation schemes, Melbourne-based researchers took a look at what doubling the amount of vegetation in the city would do to control the micro-climate.
Among the many types of vegetation studied by the Melbourne research team were different low-level vegetation like grassland and higher elevation tactics like green roofs. They concluded there is the potential to decrease heat-related mortality among the city's elderly by up to 28% and lower the temperature by 0.5 degrees Celsius by doubling the amount of vegetation in the city.
In addition to adding parkland and community gardens, great opportunities for increasing urban green space without new real estate lie on unused roofs. While some roofs cannot accommodate the weight of a green roof with dirt and vegetation, coupling initiatives to incorporate both green roofs and cool roofs via a reflective coating could lower the temperature of a neighborhood by a few degrees Fahrenheit and reduce building temperatures by up to 30 percent. This not only improves public health by reducing heat-related mortality, but it also reduces reliance on air conditioners and traditional energy use for cooling therefore reducing greenhouse gas emissions. Not to mention it adds a way for city-dwellers to experience the great outdoors.