WBUR News by Martha Bebinger

Part of a series examining the effects of climate change here in Massachusetts

This map of Greater Boston shows land surface temperatures on July 7, 2015. The redder areas are warmest. The map was created on July 3, 2017. (Courtesy of The Trust For Public Land mapping tool)

This map of Greater Boston shows land surface temperatures on July 7, 2015. The redder areas are warmest. The map was created on July 3, 2017. (Courtesy of The Trust For Public Land mapping tool)

CHELSEA, Mass. — As coastlines recede with global warming, so-called heat islands are growing. These are dense urban areas where cement or asphalt cover most of the ground, where multi-story buildings — often brick — bake in the sun, and where there are few trees.

Daily temperatures in these spots can be 20 to 50 degrees hotter than in leafy suburbs. For residents of these islands, health risks rise with the heat.

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