The city government was a petitioner in the landmark Massachusetts v. Environmental Protection Agency Supreme Court case forcing the EPA to regulate greenhouse gases as pollutants. The city is also a leader in the construction of energy-efficient green office buildings, including the Hearst Tower among others. Mayor Bill de Blasio has committed to an 80% reduction in greenhouse gas emissions between 2014 and 2050 to reduce the city's contributions to climate change, beginning with a comprehensive "Green Buildings" plan.

What percent reduction of greenhouse gases does Mayor de Blasio want to see by 2050?