The framework for this paper is the growing concern about the worldwide increasing energy consumption of telecommunications systems and data centers, and particularly the contribution of the thermal management system. The present energy usage of these systems is discussed, as well as the relationship between cooling system design and the total cost of ownership. This paper identifies immediate and future thermal bottlenecks facing the industry, ranging from technological issues at the component and system level to more general needs involving reliability, modularity, and multidisciplinary design. Based on this enumeration, the main challenges to implementing cooling solutions are reviewed. Particular attention is paid to implementing liquid cooling, since this technology seems the most promising to addressing the key thermal bottlenecks, and improving the future sustainability of thermal management in the telecom and data center industry. Finally, an outlook is presented toward future potential challenges.