Toronto City Hall's podium green roof is seen in Toronto, Canada, Oct. 30, 2015. Toronto is the first city in North America to have a bylaw to require and govern the construction of green roofs on new development. From Feb. 1, 2010 to March 1, 2015, 260 green roofs had been created in Toronto, consisting of 196,000 square metres of green roof area. A total of 444 green roofs exist in Toronto so far. (Xinhua/Zou Zheng)
