The former President – who reportedly pocketed £2.5million ($ 3.2 million) for the one and a half hour speech – appeared at the Global Food Innovation Summit on Tuesday to urge conference-goers to reduce their carbon footprints.
But footage from the event shows an ostentatious arrival, with police cars, motorbikes, and gas-guzzling armoured SUVs ferrying the ex-Commander in Chief to the event.
Mr Obama was allegedly chauffeured straight from the airport to the £7,100 (€8,400)-a-night Park Hyatt hotel in the city, reportedly with an escort of up to 300 police officers.
The former President’s armoured Chevrolet Suburban has an approximate mileage of just 16 miles per gallon (MPG) – compared to a Vauxhall Astra, which has a fuel economy of at least 46 MPG.
The motorcade was also reportedly accompanied by a helicopter – all of which brought the Italian city to a standstill.
Mr Obama took to the stage at the summit to lecture activists about the threat posed by rising temperatures.
He told the conference: “I do not believe that this planet is condemned to ever rising temperatures.
He said: “People have a tendency to blame politicians when things don’t work, but as I always tell people, ‘You get the politicians you deserve.’
“And if you don’t vote, you don’t participate, and you don’t pay attention, you will get policies that don’t reflect your interest.”