This report defines frontier technologies as new, innovative and disruptive technologies. It explores the vast potential of frontier technologies to help assess, mitigate and adapt to climate change. Leveraging these technologies to engineer new solutions to address climate change represents a significant opportunity to accelerate efforts to achieve Sustainable Development Goal (SDG) 13: ‘Take urgent action to combat climate change and its impacts,’ especially at the city level. Several UN bodies have worked closely on this report, including: the International Telecommunication Union (ITU); United Nations Educational, Scientific and Cultural Organization (UNESCO); UN Environment; United Nations Framework Convention on Climate Change (UNFCCC); United Nations Global Compact; United Nations Industrial Development Organization (UNIDO); United Nations Human Settlements Programme (UN-Habitat); United Nations Entity for Gender Equality and the Empowerment of Women (UN-Women) and with the support of the United Nations Economic Commission for Europe (UNECE). This report collates observations from the real-world deployment of eight key emerging technologies in tackling climate change: artificial intelligence (AI), Internet of Things (IoT), 5G, clean energy technology, digital twins, robotics, Space 2.0 technologies, as well as digitalization and Big Data within cities and urban regions.