This booklet is the third of its kind and, as such, the sequel to ‘Critical Issues in Sustainability – Part I’ and ‘Critical Issues in Sustainability – Part II’. It contains several of our reflections as they have appeared in writing throughout 2020, notably but not exclusively through opinion articles. Just as much as we hope this booklet will challenge your ideas and actions and will provide you with the inspiration to change our world for the better, we hope it will be the ancestor of our and others’ future work. In any case, we invite you to let us know what you think about it and how we might join forces