A United Nations study released last week found that a "deadly collision between climate change and urbanization" will take place unless effective urban planning measures can deliver energy and emissions savings. According to the study, an estimated 59 percent of the world's population will live in urban areas by 2030, and cities tend to be energy intensive. The report warned that towns and cities are vulnerable to serious consequences of increased emissions, including increased frequency of heat waves, downpours, and droughts, and increased sea level in some areas of the world. "These changes will affect water supply, physical infrastructure, transport, ecosystem goods and services, energy provision and industrial production," the study wrote. "Local economies will be disrupted and populations will be stripped of their assets and livelihoods." According to Joan Clos, executive director of UN-Habitat, local urban planners and governments may play a large role in affecting climate change, even if national governments fail to address the issue. The report specifically identifies challenges in several urban centers, including barriers to carbon reduction in cities such as Los Angeles and Sao Paulo. For the full story, see http://www.bbc.co.uk/news/science-environment-12881779. For the report, "Global Report on Human Settlements 2011, Cities and Climate Change: Policy Directions," see http://www.unhabitat.org/content.asp?cid=9599&catid=7&typeid=46&subMenuId= 0&AllContent=1. For case studies, see http://www.unhabitat.org/downloads/docs/GRHS2011/SomeCaseStudies.pdf.