and which may delay emergency vehicles which get stuck behind the idling cars. city fishes say it s worth it for the pleasure parisians and tourists derive from a leisurely walk or ride along the river there. are thousands or tens of thousands of people who are just using it now with biking, with walking or just enjoying this new park in the center of the city of paris. reporter: that may be true in the summer time. however, when the weather turns, the strollers and riders disappear. but the cars do not. what s more, the city s ambitious scheme to encourage bike sharing have had its own problems. the company behind it reporting because of vandalism and theft, 15 to 20% of the bikes were lost each year, and maintenance costs went through the roof. we have to work on each bicycle almost every 15 days. reporter: the old bicycle rental stations are being ripped
the one planet summit in paris. the meeting is happening two years to the day that nearly 200 governments agreed to take action to slow climate change. now paris has put a lot of effort into improving its air quality, but some of its attempted improvements have actually been total flops. cnn s jim bitter man hmann has s on this. reporter: you don t have to look for to see how complicated the climate change can become. right outside the paris center s front door there is a battle going on between two million parisians and the one million suburbanites who commute into the city each day. four years ago city officials began closing down along sections of the express lanes hoping to replace cars and trucks with bicycles and pedestrians in order to limit pollution. but after a year-long study, air pollution officials found that roadway closings only pushed the pollution from the river where no one lives to paris neighborhoods where people do