Bordeaux wine merchants are renowned for regularly declaring their latest offering the “the vintage of the century”. The claims go with the territory of super salesmen.

This year there is a difference. The world’s wine experts agree with the spruiking merchants. The 2005 vintage wines recently offered for sale out of their oak barrels have received lavish praise.

“One would like to call the wines classic claret, but Bordeaux has surely never known a vintage quite like this,” wrote Jancis Robinson in the London Financial Times. “The 2005 vintage will go down in the history books as a superlative year for Bordeaux,” said James Suckling in the Wine Spectator. For Jane MacQuitty of The Times, “after a frenetic week of tasting the precocious, purple-black 2005 claret straight from barrel, two years in advance of bottling, it is clear that the Bordelais have a likely vintage of the century on their hands.”

The American critic Robert Parker says the 2005’s show “compelling greatness” and describes his jubilation about the vintage with many Chateaux making their greatest wine ever: “I know I sound like a broken record,” he admits, “but here is another estate that may have produced its finest wine…ever.”

And the reason for all these superlatives? Well the experts put it down to two things; grapes that were picked small and ripe. The 2005 Bordeaux vintage was marked by above average temperatures and below average rainfall.

The growing season was the driest since 1949 with rainfall about half the 30 year average. The drought kept the grapes free of the fungal diseases they often suffer in humid weather and made them smaller and unusually low in juice. “It was the thickness of the skins, in which all flavour-, colour- and tannin-producing compounds reside, that were responsible for the 2005s’ quite exceptional charge of these vital elements.” Ms Robinson explained to her readers.

Now you can make of that what you will. Some researchers at the Davis Campus of the University of California have conducted experiments that suggest that when drunk blind, people prefer wine made from high yielding grapes more than from low yielding ones. But there is little doubt that ripeness helps quality.

Winemakers throughout Australia, where a good vintage virtually every year produces the fruit concentration and alcohol levels of the fabled French years, have long known that. So too do the growing number of customers worldwide who have made Australian wines bigger sellers than their French competitors in many markets.

It is something of a paradox that the same wine experts praising the 2005 Bordeaux are the ones who regularly write about cool climate winemaking and how this is essential to make fine wine. Yet it is wines from the uncommonly hot European summers like 1945, 1947 and now 2005 that they really rave about.

The evidence pointing to rising world temperatures suggests that soon there will be more opportunities for Bordeaux “vintages of the century”. Conditions in the nine months of the 2005 growing season saw 70 hours more sun than the thirty-year average and temperatures above the thirty-year average from 0.6 to 2.3 degrees C depending on the month, with the one exception being February when temperatures were 1.3 degrees below average.

More years like that, and French wine makers who learn how to handle ripe fruit when drought does not limit production, and Australia will have a new “old world” competitor.