The world's most iconic skylines are going green. Nineteen city leaders from the C40 coalition signed the Net Zero Carbon Buildings Declaration on Thursday to ensure all new buildings operate with a neutral carbon footprint by 2030.

The mayors of Copenhagen, Johannesburg, London, Los Angeles, Montreal, New York City, Newburyport, Paris, Portland, San Francisco, San Jose, Santa Monica, Stockholm, Sydney, Tokyo, Toronto, Tshwane, Vancouver and Washington, DC also pledged to ensure all buildings in the cities—old or new—will meet net-zero carbon standards by 2050, according to a press release. The cities are home to 130 million people combined.