Humans are altering the planet's biogeochemical cycles in a largely unregulated way with limited knowledge of the consequences. Without steps to effectively manage the Earth system – the planet's physical, chemical, biological and social components – it is likely there will be severe impacts on people and ecosystems. Perhaps the largest concern is that a component of the Earth system, for example, an ocean circulation, the Amazon rainforest, or Arctic sea ice, will reach a tipping point and flip from its current state to another state: flowing to not flowing, rainforest to savanna, or ice to no ice. A domino effect could ensue with other components of the Earth system changing state rapidly.