The plans for the 2008 Beijing Olympics are notable for their extra security amid human-rights protests. But the 2012 London Olympics' park plans are notable in that they consider a climate-changed future, in which flooding may worsen and cities must minimize carbon emissions.

London's summer-games site straddles the polluted Lea River on the east end of the city, now a moribund industrial area dotted with depressed neighborhoods. The planners looked at climate models and recognized that the area, known as the Lower Lea Valley, would likely be carrying higher flood waters from intensifying rainstorms.

Jason Prior, president of the planning firm EDAW, explained one consequence of this finding at a conference on Friday: the planners ran hydrological models to determine how to widen the river and design new bridges to accommodate the higher flows. "You survey the river systems, then project forward the impact of different flow conditions, and you add the amounts the climate models are giving you," Prior said after a forum on climate change and cities at the Lincoln Institute of Land Policy, in Cambridge, MA. "You then fine-tune the channel's cross sections, change design of bridge abutments, and design wetlands to catch the extra amounts." Site work has already begun.

Equally important in London's climate-minded preparation is the post-Olympics plan for the region. Housing for 17,000 athletes will become housing for 4,000 families; plazas will become parklands. The plan includes highly efficient housing powered partly by a wind turbine and biomass plant, with pedestrian links across the river connecting to transit stations, and new amenities like schools and shops.

This idea--planning entire neighborhoods around energy efficiency and reduced emissions--is part of an emerging trend in which efficiency is thought of as something more than discrete buildings, houses, cars, and appliances. "Missing altogether from these 'widgets' is any notion of urbanism," Douglas Farr, principal at Farr Associates, a Chicago-based planning firm that focuses on sustainable design, said at the conference. He added that planners need "urban parts"--meaning entire sustainable and efficient neighborhoods--that can be, in effect, plugged into a city or suburb.

To this end, Farr helped develop a new energy-efficiency standard called LEED-ND. This expands the existing LEED (Leadership in Energy and Environmental Design) rating system for individual buildings by adding the "ND" for neighborhood development. Features of high-efficiency neighborhoods include walkable shopping and services, bike paths, renewable district power generation, connections to mass transit, and shared car usage, perhaps assisted by location-based technologies to let residents know where and when vehicles are available.