After several years of work, the chapter’s writing team — which included engineers, planners, and economists — concluded that mitigation strategies are more effective when policy instruments are bundled and when land use and transportation planning are integrated.
“Infrastructure and urban form are strongly interwined, and together they set in place patterns of land use and behavior that are difficult to change,” Seto said. “Thinking of the city as a whole will allow for more systemic mitigation strategies that bring more emissions savings than focusing solely on individual sectors.”
One of the challenges in writing the new IPCC chapter, Seto said, was being comprehensive in the research assessed, since there has been such a surge in study worldwide. Two other complicating factors, she said, were the lack of precedent for the new chapter and the fact that none of the authors on the chapter team had experience with previous IPCC reports.
“There was no roadmap for the structure of the chapter, and we didn’t have the wisdom of experience. At the same time, there has been a lot of interest in this chapter,” she said. “Many countries are recognizing that urban-scale mitigation is where some of the most innovative mitigation strategies are being developed.”
One of the key messages of the chapter is that there is a window of opportunity, as much of the world’s urban areas will be developed this century and infrastructure lock-in and behaviors have not been set in place. “For established cities,” Seto said, “the key mitigation options lie in retrofitting their aging infrastructure and doing systemic improvements.”
In a report released on March 31
, the IPCC Working Group II concluded that the effects of climate change are already affecting the planet’s natural systems and will pose an increasingly dire threat to human health, water supplies and food security.