“Anthropocene” has been proposed as a name for the current period of Earth history, defined by the detectability of a global human ‘signal’ in the geological record; proposed starting dates range from ca. 12,000 years ago to the mid-20th century. Regardless of the acceptance of the term, human activities have induced large, global changes in atmospheric, biological, and geochemical systems. As these earth systems move into states beyond past human experience, it becomes increasingly difficult to project our future by extrapolating from where we have been. How is our time unique? Human-induced climate change will continue through the current century and beyond, taking us beyond conditions previously experienced by modern humans. Human population has approximately quadrupled in the last century and, while growth is slowing, will likely add another 2-3 billion over the next generation. Efforts to support this population involve massive rearrangements of global geochemical cycles (including massive extraction of fossil fuels) and, while these efforts have been successful so far, they raise concerns about sustainability and the compatibility of human well-being and conservation of natural systems. Extinction rates have accelerated with the redirection of planetary ecosystem function to serve human needs (humans now appropriate 1/3-1/2 of Earth’s biological productivity). New diseases (human, animal, and plant) emerge as evolution responds to environmental change. Lacking precedent from which to project planetary futures, we must use our best scientific understanding to assess options and choices and to make policy and plans in the face of uncertainty. We will explore scientific underpinnings from earth and biological sciences to understand the roots of global change, to evaluate scenarios and predictions of likely (or worst-case) consequences for global biological, climatic and geochemical systems, and to consider effects on human welfare and the sustainability of human societies?