Guardian: The Empire State Building, the symbol of New York’s pre-eminence and the world’s tallest skyscraper until 1970, is seeking to pierce through the pall of economic gloom that has descended on Manhattan by turning itself green. The owners of the building yesterday announced they were investing an additional $20m to reduce its carbon footprint and energy consumption. The retrofit is being added to a renovation of the Art Deco structure that starts this summer and is already costing half a …