4. Copenhagen, Denmark The Danish city is famous for the cycling culture which has consistently helped in reducing CO2 gas emissions. Greenhouse gas emissions have been reduced to 20% since 2005.
Nearly half of the population of Copenhagen commutes by bike everyday and there are bike lanes specially laid across the city.
The city has a lane that crosses the Dronning Louises Bridge, connecting the lively Nørrebro neighbourhood to the city centre, is the busiest bike lane in the world, with 36,000 cyclists using it daily.