Boston has joined an elite group of cities pledging to reduce its greenhouse gas (GHG) emissions 80% or more by 2050. Consider two facts: one, that 73% of Boston’s GHG emissions is attributed to buildings; and two, a typical city renews three quarters of itself through tear down, new building, and renovation about every 30 years, according to leading urban design think tank Architecture 2030. Together, they point to the need for Boston to seize the next 30-35 year natural renewal cycle and consciously use it to transform all buildings, modes of transportation, energy sources, and activities that currently produce GHG emissions. Given the large percentage of emissions attributed to buildings, the urban form and function of Boston is likely to change in many exciting and positive ways. What would a roadmap of change look like from 2015 to 2050? Ed Mazria challenges the audience to focus on the pathways for Boston to achieve de-carbonization in three short decades, from building technologies and planning approaches to policy and regulatory innovations.