Taking the City’s Temperature
Fifty “citizen scientists” volunteered to traverse Philadelphia’s streets with instruments that scan for heat islands, in a hunt to locate climate change hotspots.

_Richard Johnson

Johnson is the former director of community science in the Academy of Natural Sciences of Drexel University.

Citizen scientists from local community groups joined researchers from the Academy of Natural Sciences of Drexel University to document extreme heat and air quality across Philadelphia neighborhoods as part of an urban heat mapping project funded by the National Oceanic and Atmospheric Administration.

Working in pairs, teams traversed the city along specific routes, using special sensors mounted to their cars to measure temperatures and particulates. Pinpointing hotspots on one day, the researchers gathered data that can inform the development of strategies to prepare for climate change.

Similar heat map campaigns have been conducted in 35 communities across the U.S. over the past five years. In 2021, 799 community scientists took 1.2 million measurements in 24 communities. Cities from past campaigns have used their data to develop heat action plans, add city cooling stations, educate residents and policymakers and inform new research. 

Cities typically face higher temperatures than suburban and rural areas, and the negative effects of heat and pollution are often the worst in low-income areas with little tree cover. The data will help city officials and community advocates target resources where they are needed the most, according to Richard Johnson, who in 2022 served as director of community science at the Academy and led Philadelphia’s collaboration with NOAA.

Philadelphia was among 15 U.S. cities chosen to take part in last year’s study.