Assessing Urban Tree Canopy and Vegetation in Mitigating Urban Heat Island Effects and Heat-Related Mortality Rates: A Systematic Review

Background: Extreme heat events are increasing in frequency, duration, and severity in many parts of the world due to climate change. Certain vulnerable urban populations are disproportionately impacted by such EH events, which are exacerbated by the urban heat island effect. Mitigation and adaptation strategies including urban greening are a growing trend in many cities, but there is variability in this intervention\u27s effectiveness, dependent on the area of study. Objectives: Based on the Navigation Guide by Johnson et al., we conducted a systematic review of the literature to determine the effectiveness of urban tree canopy (UTC) and vegetation in mitigating urban heat island effects and reducing heat-related morality rates in the Northeastern and Midwestern US. Methods: In applying the Navigation Guide methodology, we followed the three step framework: 1) we identified our study question, 2) we systematically researched and chose our evidence, and 3) we rated the quality and evidence of our selected studies. We developed specific criteria to select and rate the body of literature included in this systematic review. Results: Our research resulted in the inclusion of 6 studies based on our criteria. We established the risk of bias across all studies to be fair and determined the overall quality of evidence to be moderate. Conclusion: We modified the Navigation Guide framework to better fit the studies assessed. We determined that there was limited evidence of effectiveness of UTC and vegetation in lowering air and land surface temperatures and reducing heat-related mortality rates in Midwestern and Northeastern US cities