Price peaks of wheat on the world market are mainly caused by production shocks like those induced, for example, by droughts, researchers found. These shocks are exacerbated by low storage levels as well as protective trade policies, the analysis of global data deriving from the U.S. Department of Agriculture shows. In contrast to widespread assumptions, neither speculation across stock or commodity markets nor land use for biofuel production were decisive for annual wheat price changes in the past four decades. This finding allows for better risk assessment. Soaring global crop prices in some years can contribute to local food crises, and climate change from burning fossil fuels and emitting greenhouse gases is increasing weather variability.