The major obstacles to sustainable development

Willingness
Understanding
Capacity

Gallopín, Gilberto C.(2002). Planning for resilience: Scenarios, Surprises, and Branch Points. In: Gunderson, Lance H. & Holling, C.S. (Hrsgg.) (2002). Panarchy · Understanding Transformations in Human and Natural Systems. Washington, Covelo, London: Island Press. S. 362.

Ultimately, the major obstacles to sustainable development can be reduced to three basic categories: willingness, understanding, and capacity.
The first and major obstacle has been described as a lack of political will to implement those changes that are glaringly necessary. Asymmetric power structures, vested interests, and conceptions by humankind that emphasize antagonism, competition, and individualism over cooperation and solidarity lie at the heart of this obstacle.
Even in cases where political will is present, another obstacle is the lack of understanding of the behavior of complex systems. This lack of understanding results often in a failure to address the relevant linkages within and between systems and across scales. Compartmentalized perceptions of reality and a scientific tradition and training that are still largely reductionist impair the development of understanding.
Inadequate institutions, lack of financial resources, unskilled human resources, weak infrastructure, plain poverty, and other limitations contribute to the third obstacle: insufficient capacity to perform the actions and changes needed, affecting notably (but not exclusively) the developing world.