The Anthropocene, global change and sleeping giants: where on Earth are we going?

The "climate problem" has come to the fore in public policy debates over the last year or so. The continuing high temperatures, the spate of intense tropical cyclones and deepening droughts in some parts of the world have focused attention on the issue of defining "dangerous climate change" [1]. This is often conceptualised as an upper limit to the rise in global mean temperature, for example, 2°C above pre-industrial levels, which in turn leads to a back calculation of the permissible concentration of CO2 in the atmosphere and then to the trajectories of the corresponding maximum anthropogenic carbon emissions.