Dijon: A hot year is normally associated with a vintage year for wine growers but global warming could, by the end of the century, have adverse effects on vineyards in Southern France and California.

Speaking at a conference on the impact of global warming on the wine industry Gregory Jones, associate professor of geography at the American University of Southern Oregon said "in the future, warming could become disastrous in numerous regions."

"The first studies on the consequences of global warming show that warming favours the quality of the wine but the threat might come from a series of challenges," he said, citing problems with irrigation, diseases, and soil erosion resulting from flooding.

Bernard Sequin, from the French National Institute for Agricultural Research, said, "heat, it''s sometimes a good thing, up to a certain threshold," citing the heat wave that hit Europe in 2003 gave some idea of what is in store in the future.

"(This) was generally positive for the harvests in the North France but less so in the South," Sequin said.

The regions most threatened by global warming are those with the hottest climates, such as Southern Europe and California in the US.

If nothing is done about global warming, only the coastal regions of California, cooled by the ocean breeze, will be good for cultivating vines by 2100, Jones said.