Spurred by legislation such as State Assembly Bill (AB) 32 and State Senate Bill (SB) 375—which mandate greenhouse gas (GHG) reductions and sustainable community development—California municipalities have led the U.S. in responding to climate change in recent years. Now towns, cities and counties across the country are following suit.

"We're working with more and more municipalities outside California who are taking action without legislation, recognizing that legislation will be forthcoming or that environmental and economic realities will demand action regardless," said Claire Bonham-Carter, AECOM director of sustainable development in San Francisco.

Climate change will have a massive impact on infrastructure and public health, and municipalities must absorb the financial ramifications.

"Sea level rise will increasingly be a concern for buildings and infrastructure within proximity to the ocean," said Christopher Clement, AECOM sustainable economist in San Francisco. "In a sea level rise strategic program developed for Solano County, California, we estimated that for the near-term projection of a 16-inch sea level rise, over 27 miles of roads and highways and 865 acres of built land would be impacted, with replacement costs of approximately $462 million and $133 million respectively."

"In an economic impact study of California's SB 375, we found that if fully realized, the cohesive regional land use, transportation and air quality framework would be economically advantageous in a number of ways, including addressing the disequilibrium in market demand, further developing the regional economy and employment base and increasing fiscal efficiency," said Alexander Quinn, AECOM director of sustainable economics in San Francisco.

"Another study we did found that with a simpler permitting process, roof-top solar installations could provide the California economy with $5 billion in growth by 2020."

Climate action planning is an interdisciplinary process that more and more municipalities are pursuing across the country to reduce their greenhouse gas (GHG) emissions and adapt to the already inevitable impacts of climate change. Informed by environmental science, climate change mitigation and adaptation measures translate into everything from policy, to land use and transportation planning, to architecture and building engineering, to urban and landscape design.

"Public participation is a crucial aspect of the climate action planning work we've done," said Laura Cacho, AECOM economist and planner in Alexandria, Virginia. "No plan is going to succeed if it was developed without involving the community and understanding what lifestyle changes they are willing to make."

"GHG inventories are the critical first step in developing a climate action plan—letting municipalities know where their emissions come from, helping them set achievable reduction targets and prioritize measures that will help reach those targets," said George Lu, AECOM environmental planner in Kansas City, Missouri.

"A majority of GHG production occurs from poor land use and transportation planning, which leads to people having to do a lot of driving," said Jeff Henderson, AECOM urban planner in Sacramento. "Mixed-use development that inherently requires less travel, linked with transit options such as light rail and bicycle, provide a low-carbon solution."

"Increasing the energy efficiency of buildings constitutes a major factor in enabling cities to reduce their dependence on fossil fuels," said Alastair MacGregor, who leads AECOM's High Performance Buildings group in Orange, California.

"This can be done through innovative approaches to the engineering of new buildings, building commissioning to make sure that buildings operate as they were designed to and also through smart renovations of existing structures."

"Finding the balance between accepting, confronting or retreating from the impacts of our changing environments forms the key decision when designing for climate adaptation at the water's edge," said Sandy Fischer, AECOM design director in Seattle. "These decisions are the responsibility of every community, resident and city along the waterfront and must be made collaboratively on a regional scale and implemented at the site level with consideration of the larger adaptation goal.

On the Richmond waterfront in British Columbia, AECOM developed a planning and landscape design solution that considered rising sea levels, increased runoff from snow melt and population increases.

Political leaders including former President Bill Clinton and New York Mayor Michael Bloomberg recently discussed efforts to address climate change at the fourth biennial C40 Cities Mayors Summit in Sao Paulo, Brazil.

"It was helpful for us to learn how mayors all over the world view climate change and are responding it," said Claire Bonham-Carter, who attended the summit and a new Business Advisory Council on behalf of AECOM. "There is no text-book on how to do this—cooperation and sharing of best practices between public and private sector and across geographies is absolutely critical."

Jake Herson