 Berkes and Folke table a set of principles to assist with "building resilience and sustainability" which consolidate approaches of adaptive management, local knowledge-based management practices and conditions for institutional learning and self-organisation.More recently, it has been suggested by Andrea Ross that the concept of sustainable development is no longer adequate in assisting policy development fit for today's global challenges and objectives.This is because the concept of sustainable development is "based on weak sustainability" which doesn't take account of the reality of "limits to earth's resilience".