1. Introduction

Urbanization has become one of the most omnipresent features of the twenty-first century world. More than half of the world’s population lives and develops their activities in cities, and by 2050, this figure is expected to include two-thirds of people worldwide. These urban changes have created specific natural and social environments, including urban climates, not only in the large metropolis, but also in mid-sized cities. In this context, this chapter introduces the main urban, environmental, and climatic problems of Latin American cities. The modification of the local climate is characterized by a change of climate conditions, with higher temperatures, lower humidity and ventilation, atmospheric pollution, and poor environmental quality. In Latin American cities, these conditions have large geographic variations in terms of latitude (from 32°N to 56°S), altitude (from sea level to over 5,000 m), watershed, topography, and ocean influence, among other natural factors. Using the Urban Climate System Monteiro (Teoria e clima urbano. 16 USP/FFLCH thesis (Livre-docência), São Paulo, 1976) approach, the book is structured in three parts or subsystems: thermodynamic, physiochemical, and hydrometeorological subsystems. The focus is on the geographic dimensions of thermal comfort, air quality, and extreme events, and how, through planning and adaptation, proposals can be developed to cope with such challenges.