Lessons from planned resettlement and new town experiences for avoiding climate sprawl.

• Climate change will lead substantial numbers of people to relocate. • Problems from unmanaged retreat include scattered growth or rising costs in attractive areas. • The history of new towns provides lessons for the coming wave of planned retreat. • Resettlement experience to date provides good practice examples. • Whole-community and new-community resettlement can foster social ties. Climate change will cause substantial numbers of people to relocate, whether in a planned or more ad hoc manner. In receiving communities this could lead to substantial problems supplying physical infrastructure, preserving affordability, conserving wild and productive lands, maintaining social connections, and providing community services in new areas. Moving to comprehensively planned new settlements could be a solution to climate sprawl (fragmented and dispersed development) and climate gentrification (increased demand in existing areas). This may involve moving an entire settlement as a whole to a comprehensively planned neighborhood or town. We call this " whole community" retreat as it keeps social ties intact. An alternative involves creating a comprehensively planned new town or new neighborhood for people from a variety of locations. We refer to this as " new community" retreat as it provides a new environment, but social ties need to be developed. The paper examines lessons from two sets of experiences with large scale resettlement or community-building. One group of examples involves whole community resettlements after disasters or related to economic development and a second set of precedents come from the broader history of new towns. Challenges from both resettlement experience and new town history include land and infrastructure availability and cost, planning and development coordination, financing, and attracting a large enough proportion of people to keep social ties intact. A more comprehensive approach has benefits, but is easier to pull off at a neighborhood rather than a larger scale and for shorter rather than longer moves. [ABSTRACT FROM AUTHOR]