As described in my blog post of the same name, there will soon come a time when an overabundance of vertical surfaces will result in an effective inversion of the seasons, and will necessitate the mitigation of solar heat gain (the bureoning technologies of solar power, integrated vegetation, passive heating, etc.) primarily through a building's facade rather than its roof. The magnitude of such an initiative when applied to heavily-developed urban centers will be considerable.
Below: Sao Paulo.
Winter 2012