London is a city known for Big Ben, the Eye and a strong commitment to reduce carbon-dioxide emissions.

But, according to a study U.K. researchers expected to publish Wednesday evening, the city's plan to cut 60 percent of carbon-dioxide emissions reduction by 2025 is not enough to avoid dangerous climate change.

In their study, which will appear in The Lancet, a research journal, researchers from the London School of Hygiene and Tropical Medicine and a University of Oxford-based research center concluded that the entire city needs to become car-free. And the kicker:The proposal also includes a ban of more eco-friendly alternatives, such as electric cars.

Perhaps it's extreme. But if such a ban is possible anywhere, London is a prime candidate. After all, the region has been known to adopt once-upon-a-time radical ideas, like central London's congestion charge, where some motorists entering the area pay a fee.

Still, some said the car ban is unlikely.

"I'm a really creative, imaginary person. But I have a hard time imagining London without cars," said Joe Bowman, CEO of the U.K.-based, light electric-vehicle manufacturer Ultra Motor, adding that more public transportation and bicycles would be needed to help pull off the ban.

The study does encourage more public transportation, and people climbing onto their bicycles. The study also calls for an increase in cabs, and more clean technologies within the public-transportation fleet, such as hybrids.

Sure, "it's a long way from what's happening in any place at the moment," admits James Woodcock, lead author on the study, which also included the Oxford University Centre for the Environment's Transport Studies Unit . "But I think there are going to have to be big changes across all sectors if we are going to avoid catastrophic climate change."

Woodcock's study suggests a car ban could help London achieve a 72-percent emissions reduction by 2030.

Perhaps Woodcock's vision isn't as quirky as it sounds. The study points out that cars contribute 60 percent of London's passenger land-transport emissions. And the bulk of them aren't going very far, with 59 percent of car journeys racking up between 1 and 8 kilometers, or 0.62 to about 5 miles.

Woodcock points out London was consciously selected as the study's subject due to the region's willingness to take on pioneering transportation policy.

Going to Extremes

The inclusion of more eco-friendly cars is bound to stir up some controversy. But Woodcock said until there are more guarantees that the original power sources, such as electricity, were created in a clean way, the restriction would have to apply.

Such conclusions don't appear to scare Bowman. "This is one of the only cities in the world where you can't spend five minutes downtown and not see an electric car," he said. The vehicles' prevalence is partially attributed to the fact that the cars are exempt from the congestion tax.

When Bowman peers into London's future he sees electric cars as part of the solution. And so does Thilo Koslowski, lead automotive analyst for Gartner.

Koslowski also says that to reach aggressive emission-reduction targets, cities like London will of course need to consider alternative vehicles for public transportation. And business will also have to play their part, he said, which might include replacing entire vehicle fleets.

"Of course there will be lots of opposition because individuals and businesses are going to have to make significant investments," he said.

As city centers look to battle pollution and control emission, they'll be forced to make some tough decisions. Which means that regardless of the path taken, be it a car ban or not, "we will see more stringent requirements from local authorities," Koslowski said.