In fact, over 40% of civil conflicts in the 20th century had a link to natural resources, often as a contributing cause, by financing arms, or acting as a flashpoint for small-scale conflict that becomes embroiled in larger ethnic, political or economic conflict, which can spiral out of control. In the post-conflict period, extraction of natural resources (mining, timber, firewood forestry, fishing) is often the only livelihood option for returning displaced populations. All too often, unsustainable practices become embedded as the new norm, setting up the conditions for severe resource stress in the future.
As a historian, I am extremely sceptical of arguments based on monocausation. Although I am a medievalist, I have had to teach across a lot of periods and cultures, and my conclusion wrt wars and conflicts is that they are almost all bother over determined and under determined. There is a certain chaos in human affairs which social scientists just do not seem to be able to acknowledge.
Figures such as "40%" can only be made by discarding a lot of actual information to create "all other things not considered" scenarios.