We maintain that humanity’s grand challenge is solving the intertwined problems of human population growth and overconsumption, climate change, pollution, ecosystem destruction, disease spillovers, and extinction, in order to avoid environmental tipping points that would make human life more difficult and would irrevocably damage planetary life support systems. These are not future issues: for example, detrimental impacts of climate change (increased wildfires and extreme weather, sea-level rise, ocean acidification), pollution (contaminated drinking water in many parts of the world), rapid population growth in some areas (contributing to poverty, war, and increasingly frequent migration) and overconsumption in others (a main driver of overexploitation of resources and greenhouse gas emissions), and new disease outbreaks (Ebola, Zika virus) already are apparent today, and if trends of the past half century continue, even more damaging, long-lasting impacts would be locked in within three decades. Solving these problems will require some scientific and technological breakthroughs, but that will not be enough. Even more critical will be effective collaboration of environmental and physical scientists with social scientists and those in the humanities, active exchange of information among practitioners in academics, politics, religion, and business and other stakeholders, and clear communication of relevant issues and solutions to the general public. This special feature offers examples of how researchers are addressing this grand challenge through the process of discovering new knowledge and relevant tools, transferring insights across disciplinary boundaries, and establishing critical dialogues with those outside academia to help effect positive global change.