Brazil's soya exports could slump by more than a quarter over the next 12 years as the result of climate change, according to a study to be presented at an agribusiness conference opening in São Paulo today.

The study will add to concern over worsening food shortages around the world. It shows that even moderate rises in temperatures would cause significant damage to a range of agricultural produce in Brazil, which has emerged over the past decade as one of the world's biggest suppliers of food crops.