What is a Ship’s Carbon Intensity Indicator and has it anything to do with fuel efficiency?

What is a Ship’s Carbon Intensity Indicator and has it anything to do with fuel efficiency? IMO is defining a rule set for short-term measures to reduce the CO2 emissions from Shipping. The reduction towards 2030 is targeted for 40% (towards the 2008 values) and one of the measures is, that in the near future…