Top 40 questions in coupled human and natural systems (CHANS) research

Understanding and managing coupled human and natural systems (CHANS) is a central challenge of the 21st century, but more focus is needed to pursue the most important questions within this vast field given limited research capacity and funding. We present 40 important questions for CHANS research, identified through a two-part crowdsourcing exercise within the CHANS community. We solicited members of the International Network of Research on Coupled Human and Natural Systems (CHANS-Net) to submit up to three questions that they considered transformative, receiving 540 questions from 207 respondents. After editing for clarity and consistency, we asked the network's members to each evaluate a random subset of 20 questions in importance on a scale from 1 (least important) to 7 (extremely important). Questions on land use and agriculture topped the list, with a median importance ranking of 5.7, followed by questions of scale, climate change and energy, sustainability and development, adaptation and resilience, in addition to seven other categories. We identified 40 questions with a median importance of 6.0 or above, which we highlight as the current view of researchers active in the field as research questions to pursue in order to maximize impact on understanding and managing coupled human and natural systems for achieving sustainable development goals and addressing emerging global challenges.