Human preferences, practices and actions are the main drivers of global environmental change in the 21st century. It is crucial, therefore, to promote pro-environmental behavior. In order to accomplish this, we need to move beyond rational choice and behavioral decision theories, which do not capture the full range of commitments, assumptions, imaginaries, and belief systems that drive those preferences and actions. Humanities disciplines, such as philosophy, history, religious studies, gender studies, language and literary studies, psychology, and pedagogics do offer deep insights into human motivations, values, and choices. We believe that the expertise of such fields for transforming human preferences, practices and actions is ignored at society’s peril. We propose an agenda that focuses global humanities research on stepping up to the challenges of planetary environmental change. We have established Environmental Humanities Observatories through which to observe, explore and enact the crucial ways humanistic disciplines may help us understand and engage with global ecological problems by providing insight into human action, perceptions, and motivation. We present this Manifesto as an invitation for others to join the “Humanities for the Environment” open global consortium of humanities observatories as we continue to develop a shared research agenda.