Cross-sectoral issues related to critical infrastructure and security have not received a great deal of attention to date in research literatures in general and climate change assessments in particular. This paper analyzes how climate change vulnerability will impact critical infrastructure in the United States including food and agriculture, energy, water, communications, transportation systems and health care and public health. Next the paper will analyze how the concept of critical infrastructure and its interdependencies with other sectors is linked to national and homeland security and argue that risks from climate change need to be addressed in our homeland and national security policies.   A central theme of the paper is that vulnerabilities and impacts are issues beyond critical infrastructures themselves. The concern is with the value of services provided by critical infrastructures, where the true consequences of impacts and disruptions involve not only the financial costs associated with the clean-up, repair, and/or replacement of affected infrastructures but also environmental, social, political and economic effects as supply chains are disrupted, economic activities are suspended, health and safety risks are increased and our homeland and national security is threatened.  

Currently, public policy and planning about vulnerability concerns tends to be focused on extreme weather events associated with climate change that can disrupt critical infrastructures, often cascading across infrastructures because of extensive interdependencies –threatening health and local economies, especially in areas where human populations and economic activities are concentrated in urban areas. However, public policy and planning efforts need to be focused on not on singular events but on the long term assessments of vulnerabilities, risks, and impacts associated with moderate to severe climate change on critical infrastructure.  The paper concludes with examples of promising approaches for risk management, based on emerging lessons from a number of innovative initiatives in U.S. cities to protect and adapt critical infrastructure.