CICERO Second Opinion list Key scientists Published 27.02.2019 Please visit www.cicero.green for updated list. Share this CICERO Shades of Green CICERO Second Opinions are graded dark green, medium green and light green to offer investors better insight in the environmental quality of green bonds. Investors reward CICERO Second Opinions Investors in the green bond market have awarded CICERO Center for International Climate Research as the best provider of external reviews. This is the second international award for CICERO’s work on green bonds in a month’s time. Biggest second opinion provider CICERO was the biggest provider globally of second opinions on green bonds in 2016, according to an analysis by Environmental Finance.