The Coolest Spots in the Hottest Cities

Last week Bloomberg explored the coolest spots inside the world's sweltering cities. Using thermal radiometer equipment aboard orbiting satellites NASA and ESA are able to explore ground temperatures at a street-by-street level. The detailed maps of these temperature recordings can then be used to discover which areas in towns and cities are urban heat islands and which areas provide cool relief during the hottest weather. 

Bloomberg has used satellite imagery from ESA to examine in detail the hottest and coolest neighborhoods in a number of global cities (London, Delhi, Fez, Los Angeles, Melbourne and Seville). 

Their analysis of these maps is at times unsurprising. Most people are probably already aware that parks and trees can provide relief from extreme temperatures. However the maps also reveal that we can learn from the past. For example in Fez, Morocco satellite imagery reveals that modern suburbs built along wide roads are much hotter neighborhoods than older neighborhoods in the city which were built with clay bricks and much narrower streets. 

In Seville architects are experimenting with an ancient Iranian technology - qanats. These are underwater aqueducts which are used to cool the buildings built above them. Los Angeles is experimenting with using reflective paint on rooftops to reflect sunlight back into space. While Melbourne has started to install permeable asphalt to help rainwater reach tree roots, which helps promote the healthy growth of trees and the shade provided by healthy tree canopies. 

One of the best ways to prevent urban heat islands is to provide more tree canopy cover - to create natural shade. Planting more trees in urban environments not only helps to reduce street-level temperatures, they can also contribute to a better quality of life and can make neighborhoods more attractive places to live.

Google's Tree Canopy Insights interactive map visualizes the level of tree canopy cover in a number of major U.S. cities. The map is designed to show the current tree canopy coverage in each city and to help identify where new tree planting efforts are most needed. The map allows you to see the level of tree canopy coverage in different neighborhoods in each city alongside demographic data, such as population density. Using the map it is therefore possible to quickly identify where the most people are likely to be living in urban heat islands and where new tree canopy cover is most needed.