The Anthropocene refers to an epoch in which humans have become the dominant driver of planetary change, affecting the Earth system on varying timescales. Human societies have even formed a new sphere of the Earth system — the ‘technosphere’ — that encompasses all human-made materials and structures, weighs more than 30 trillion tonnes and is markedly altering fundamental energy flows. Anthropogenic action through this technosphere is bringing us closer to a series of tipping points that — if crossed — will irreversibly alter the state of the Earth. Although there is a clear acceleration of human impacts on the Earth system in the mid-20th century, research in archaeology and palaeoecology suggests that thresholds of human–Earth-system interactions may also have been traversed in the past. From the expansion of food production by 6,000 years ago to the onset of the ‘Columbian Exchange’ in AD 1492, past human societies have left an important Earth system heritage for the contemporary world.

In this article Patrick Roberts and his colleagues discuss how projecting and managing the feedback between tropical deforestation and global Earth system dynamics, and identifying potential critical thresholds or tipping points, will be key to our species’ future on this planet. By understanding the major historical processes that underpin the origins of this interaction, and bringing natural and social systems together in interdisciplinary models, they can evaluate the degree to which past human impacts on tropical forests resulted in observable planetary ramifications that have left legacies for the twenty-first century and beyond.