Many cities are aiming for neutrality by 2030 or 2050. The Danish capital plans to be the first carbon-neutral capital in the world and to hit the goal by 2025.

If you miss the metro as you walk up to a stop in central Copenhagen during rush hour, you won’t wait long for the next train: the automated system is designed to run every two minutes. It’s one way for the city to convince residents not to drive a car, and as the metro system expands, one small piece of the city’s ambitious plan to cut emissions.

Six years ago, the city of Copenhagen set the goal to become the first carbon-neutral capital in the world, shrinking energy use as it shifts to renewable energy and produces enough extra green power to offset other remaining emissions. It plans to reach the goal by 2025, while some other cities, including Washington, D.C., are aiming for as late as 2050. So far, it has cut emissions 42%, and city leaders believe it is on track to hit the target. The city is working to become “one of the world’s greenest and most bike-friendly cities,” says Frank Jensen, the city’s lord mayor. “This is the best way forward, because it creates better space, cleaner air, less noise, and a healthier city.”