This paper, authored by Haider Taha from the Lawrence Berkeley National Laboratory, reviews the characteristics of urban climates and the causes and effects of urban heat islands. It specifically examines the impacts of surface albedo, evapotranspiration, and anthropogenic heating on near-surface climates. Numerical simulations and field measurements indicate that increasing albedo and vegetation cover can effectively reduce surface and air temperatures near the ground. The paper discusses the sensitivity of the temperature field to changes in these parameters, using the URBMET model and the Colorado State University Mesoscale Model (CSUMM) for simulations. The results suggest that localized afternoon air temperatures can be lowered by up to 4°C by changing the surface albedo from 0.25 to 0.40 in a typical mid-latitude warm climate. Additionally, the paper highlights that evapotranspiration from vegetation can create "oases" that are 2-8°C cooler than their surroundings, and that anthropogenic heating can contribute to urban heat islands, particularly in cold-climate urban centers during winter. The conclusion emphasizes that cities can reverse heat islands and offset their impacts on energy use by increasing the albedo of roofing and paving materials and reforesting urban areas.This paper, authored by Haider Taha from the Lawrence Berkeley National Laboratory, reviews the characteristics of urban climates and the causes and effects of urban heat islands. It specifically examines the impacts of surface albedo, evapotranspiration, and anthropogenic heating on near-surface climates. Numerical simulations and field measurements indicate that increasing albedo and vegetation cover can effectively reduce surface and air temperatures near the ground. The paper discusses the sensitivity of the temperature field to changes in these parameters, using the URBMET model and the Colorado State University Mesoscale Model (CSUMM) for simulations. The results suggest that localized afternoon air temperatures can be lowered by up to 4°C by changing the surface albedo from 0.25 to 0.40 in a typical mid-latitude warm climate. Additionally, the paper highlights that evapotranspiration from vegetation can create "oases" that are 2-8°C cooler than their surroundings, and that anthropogenic heating can contribute to urban heat islands, particularly in cold-climate urban centers during winter. The conclusion emphasizes that cities can reverse heat islands and offset their impacts on energy use by increasing the albedo of roofing and paving materials and reforesting urban areas.