On 22 April, 1970, the first Earth Day, millions of people took to the streets in cities and towns across the United States, giving voice to an emerging consciousness of humanity’s impact on planet Earth. How has the planet changed over the last fifty years, what will it look like in 2070, and how will our current understanding of Earth’s trajectory map onto the reality that unfolds over the next half century? In his introduction, Tortell outlines the story and motivation behind the present volume, providing a chronological overview of developments in global environmental politics since the first Earth Day. He simultaneously acknowledges the progress we have made in addressing a range of acute environmental problems, and draws attention to the more pernicious threats that have emerged since the first Earth Day. Tortell summarizes the brief which he gave to the contributing authors of Earth 2020, and which resulted in the present volume: to reflect, from their own specialized vantage points, on how Earth and its human inhabitants have changed over the past fifty years, and to consider what the future might look like another in fifty years’ time. The scope of the volume is also delineated – from authors examining biophysical components of the Earth System, to those examining impacts on organisms and ecosystems, to those exploring the shifts in political, legal, economic and media landscapes that have occurred since 1970. Finally, Tortell calls for increased breaking of traditional boundaries, and conversations across domains of expertise, including new multimodal approaches to engage broader audiences who feel increasingly overwhelmed in the age of information overload.