The Paris agreement fixed worldwide targets on the temperature increase below 2°C in the XXI century. Presently 176 countries ratified this framework. With the 20-20-20 package, the European Commission fixes three targets: (i) reduction of the European greenhouse gas emissions at least 20% below 1990 levels by 2020, (ii) 20% of EU energy consumption must come from renewable resources by 2020 and (iii) 20% reduction in primary energy use compared with projected levels, by improving energy efficiency. To achieve these global targets, Covenant of Mayor was launched in 2008 as a voluntary initiative for local administrations that decide to adopt a plan of interventions concerning greenhouse gas mitigations achieving and exceeding the EU climate and energy targets. In the present paper, we analyse the global results of the initiative during its first decade of activity, focusing on the Italian case at national level, since it is presently the leading country in terms of population involved.