Small islands are recognized for their vulnerability to climate change. In this context, mitigation and adaptation policies are needed, but the ecological transition must be based on data. This study aims to assess the level of sustainability reached by 26 of the inhabited Italian small islands; it collects and analyzes the data and initiatives on the energy, mobility, waste, and water sectors and discusses the islands’ steps toward sustainability. The findings show that 18 of the 26 islands are not interconnected with the national grid and that the renewable sources cover less than 5% of the energy demand on 25 of the 26 islands. The number per capita of private vehicles reaches 90 cars per 100 inhabitants on three islands. The average of the separate collection of waste on the islands is 52%, which is far from the minimum recommended threshold of 65%. Pipelines or tankers on 17 of the 26 islands guarantee the water supply, and desalination plants are still not the rule, while the presence of wastewater treatment has been detected on 12 islands, and it often provides only partial treatment. An ambitious multi-stakeholder sustainability plan for each island should be developed to overcome the typical barriers of the island and to increase the building capacity in order to use economic incentives for that goal.

The spatial–temporal distributions of nitrogen dioxide (NO₂) in a rural area of Tiber valley were evaluated over one year (March 2022–February 2023) using remote sensing and in situ measurements. Surface concentration monitoring was conducted using a Pandora-2s spectrometer and a chemiluminescence analyzer operated at the Liberti Observatory (CNR-IIA). In spring, when the growing season and the agricultural activities increase, NO₂ peaks were detectable by the Pandora but not by the in situ analyzer. The tropospheric Pandora and TROPOMI VCD products showed similar temporal patterns as those of the analyzer at the Observatory. High TROPOMI VCD levels in spring were detected at the Observatory and at six sites selected as representative of rural, residential, and industrial environments. WRF simulations found that high pollution events, observed by the Pandora and analyzer, occurred in calm wind conditions, favouring the accumulation of NO₂ locally emitted. The complementary dataset provided by remote sensing and in situ techniques efficiently captured the spatial–temporal NO₂ variability in a rural site exposed to low emission sources, thus supporting future decisional policies and actions.

This paper reviews how European islands are taking the lead in the European Union (EU) Clean Energy Transition by reviewing the lessons learned in the EU Bridge initiative and in a number of EU co-funded projects such as NESOI, RE-EMPOWERED, REACT, IANOS, LOCALRES, MASTERPIECE, SINNOGENES, SMHYLES, STEPWISE, and ISLET. Islands encounter significant difficulties in the management of their energy systems, including strong seasonal variations in energy demand, high operational costs and GHG emissions for energy production, weak energy grids, lack of technical skills, and difficult access to finance. However, they also have positive features that make them ideal laboratories for energy transition, including high potential for renewables, small-scale and strong community structures, and high energy prices, which make most solutions cost-effective. Each of the projects contributing to the paper has been supporting the islands’ energy transition, leveraging different enabling technologies, such as renewable energy production systems, smart grids, advanced energy storage systems, and local energy community schemes. The results from these projects underline the need for tailored energy planning, considering geographical and socio-economic particularities, the need to engage the local population in the definition of the most suitable decarbonization pathways for the island, and a number of lessons learned on the technologies that have the highest potential for being tested on islands and then being replicated on the mainland. Therefore, this study concludes that renewable energy solutions coupled with different technologies (storage, mobility, district heating/cooling, etc.) and leveraging powerful community integration confirm that European islands can drive the decarbonization strategy of the EU.