The information and communication technology (ICT) sector has evolved from a nascent industry into a pervasive global utility, now connecting two-thirds of the world's population. This rapid digitalization, however, carries a significant environmental footprint, primarily driven by increasing energy demands and associated greenhouse gas (GHG) emissions. Estimates of the sector's share of global carbon emissions vary widely across the literature, ranging from 1.5% to 4%. A recent report from the World Bank and the International Telecommunication Union (ITU) places this figure at a minimum of 1.7% of global emissions as of 2022, representing 567 million metric tons of carbon dioxide equivalent (tCO_2e). This places the ICT sector's environmental impact in a comparable class to the global aviation and shipping industries, which are responsible for 1.9% and 1.7% of global emissions, respectively.
The broad range in emission estimates is not an indication of a lack of rigorous analysis, but rather a symptom of the inherent complexity and a notable absence of standardized global metrics for measuring the sector's true environmental impact. The ICT ecosystem is vast and fragmented, encompassing everything from network infrastructure and data centers to a multitude of consumer devices. This lack of a unified measurement framework creates a data gap that can obscure the full scale of the industry's environmental responsibilities. In response, global organizations like the GSMA and ITU are actively working to address this issue by developing a common set of indicators and key performance indicators (KPIs) to better measure and compare energy efficiency across different networks and regions. These efforts are designed to provide a consistent view that accounts for factors beyond an operator's control, such as geography, climate, and spectrum holdings.
Despite its substantial footprint, the ICT sector also serves as a critical enabler of decarbonization for other industries, a concept often referred to as the industry's "handprint". Mobile and digital technologies, such as smart cities, smart grids, and smart manufacturing, are estimated to enable carbon reductions that are up to 10 times larger than the mobile industry's own carbon footprint. This dual role positions the sector as both a source of environmental challenge and a vital catalyst for the broader global green transition. The ongoing development of technologies such as AI and IoT is poised to further enhance these enabling capabilities, even as they contribute to the sector's own energy consumption.

The concept of a "smart city" is often oversimplified, reduced to a municipality with ubiquitous Wi-Fi and advanced digital displays. An expert-level definition, however, reveals a far more complex and holistic urban model. A smart city is an urban center that strategically leverages technology, human capital, and sound governance to enhance sustainability, efficiency, and social inclusion for its inhabitants and businesses. It transcends the simple deployment of digital tools and instead focuses on their intelligent application to optimize resource utilization, reduce emissions, upgrade essential services, and foster a more responsive city administration. The European Union's Smart Cities Marketplace exemplifies this multi-faceted approach by acting as a collaborative forum that unites cities, industries, investors, and researchers with the shared objectives of improving citizens' quality of life and meeting European energy and climate targets.
The foundational premise of a smart city presents a critical paradox. While the model is heralded as a key solution to pressing urban challenges such as climate change and resource scarcity, its very existence is dependent on a massive, energy-intensive technology ecosystem. This creates a central tension that must be explored. The smart city is simultaneously a powerful driver of environmental solutions and a significant contributor to the global digital footprint. This report explores this duality, analyzing how the promises of smart cities can be reconciled with the realities of their environmental impact.