The essay describes the relationship between ecological crisis and urban development, as analyzed by studies that describe urban systems using a thermodynamic perspective. The concept of city will be analyzed as a «dissipative structure» - an open system that discharges disorder outside in order to maintain internal order - and as an «incomplete ecosystem» - a system that can only function correctly over time if it draws on natural resources from external territories, which are therefore dominated and exploited. This perspective allows us to highlight the complex links between environmental issues and the organization and functioning of cities in a global context.