According to the Intergovernmental Panel on Climate Change (IPCC), the mean temperature of the atmosphere will continue to rise by up to several degrees centigrade by the end of the century. The implications for humankind and the environment will be dramatic.

While news reports and disaster movies remind us about tipping points for Arctic melt and sea level rise, some things closer to home get less attention. Take food supply: new modelling studies show that there are climate tipping points here too, beyond which crop yields will collapse.

In the past, global climate modelers could realistically simulate either the atmosphere or the ocean, not both at once. Now a new "hybrid" model at the National Center for Atmospheric Research manages the feat. Its developers say it shows how minute changes in solar radiation can cause major climate swings such as the medieval Little Ice Age. But other researchers say such claims are premature.