[1] FEEM, I-20123 Milan, Italy
[2] CMCC Ctr Euromediterraneo & Cambiamenti Climat, I-73100 Lecce, Italy
[3] Commiss European Communities, Joint Res Ctr, Inst Environm & Sustainabil, I-21027 Ispra, VA, Italy
[4] Univ Bocconi, Dept Econ, I-20136 Milan, Italy