Research into the effects of global warming on wine vintages suggests the future is bright for some, gloomy for others. Researchers from three US universities found that, as temperatures have risen over the past 50 year, vintages in areas with cooler climates have improved while vineyards in warmer regions have suffered.

The researchers, from Southern Oregon University, Utah State University and the University of Colorado, studied 27 renowned wine regions in nine different countries. Using Sotheby's vintage rating system, they found that most vintages improved as temperatures rose by an average of 1.3 degrees Celsius over the past 50 years.

The effects were strongest in traditionally cooler climate regions, such as the Mosel and Rhine valleys in Germany. However, regions with warmer climates, such as Italy's Chianti region, could see grapes ripen too quickly under even hotter temperatures, and alcohol content and acidity unsettle the balance. This year's unseasonably hot summer over Europe could provide an idea of the shape of things to come, the researchers said.

The findings are due to be published in a future issue of the journal Climatic Change.