Serious brownie points this week must go to the organisers of a conference on wine and climate change

The organisers of the conference on wine and climate change, to be held in Madrid in February 2008, have snapped up Al Gore as a key speaker. The effect of global warming on wine is a major concern, as acknowledged by Jancis Robinson in the introduction to the new sixth edition of the World Atlas of Wine (Mitchell Beazley, £35). In the six years since she joined Hugh Johnson for the fifth edition, the queen bee of wine writing lists as major developments the move towards red wine, the return to native grape varieties and the growing interest in organic and biodynamic wines. "Perhaps inevitably the most notable overall development between this edition and the last has been the observable changes in climate virtually everywhere and their effects on what sort of wines are produced where."

When Johnson first brought the World Atlas of Wine out in 1971, its ground-breaking nature lay in highlighting the relationship between location and wine. And, as Robinson says, "I am thrilled to see, after decades during which winemakers and grape varieties, not to mention scores, threatened to take precedence over what really creates wine, that the world of wine is increasingly preoccupied by its most important aspect, geography." But geography is about both location and climate, and it's arguable that the Atlas could, in the virtually unchanged section on Wine and Weather, elaborate more on the effects of global warming.

The Atlas continues to put the vineyards of the classic wine regions under the microscope. Look up Pauillac in Bordeaux, for instance, and you're presented with an intricate jigsaw of cru classé vineyards with the names of the most important estates clearly visible. Much the same goes for Burgundy, although since Robinson asserts that "the name of the grower, as ever, must be your guide", greater emphasis on the individual producer would be helpful. The same is true of regions such as champagne and barolo. Anomalously, where you most want to locate the producer, there's not enough space, whereas relatively unexciting areas such as Entre-Deux-Mers have more than enough space to include the names of apparently "notable producers".

Given their centuries-old history, the maps of the classic regions have an immutability about them that creates a sense of déjà vu. The fascination of an evolving world of wine lies in the depiction of developing new regions and vineyards both in Europe and – perhaps more importantly today, given its rapid rate of expansion – the New World. There are new maps of Barossa Valley, Eden Valley, McLaren Vale and Adelaide Hills. New Zealand, too, has new maps for the two major pinot noir regions of Martinborough and Central Otago, while the sections on Chile and Argentina have been expanded.

In the absence of an appellation contrôlée route map in the New World, there's more room here for subjective interpretation of potential. Is the source of the best wines the producer's vineyard, or from elsewhere? Indeed, how much is down to the producer and how much to location? To meet this difficulty, the maps are randomly sprinkled with "noted vineyards" and "notable producers". But the two don't necessarily correspond. Henschke's Hill of Grace in Australia, for instance, is made from Henschke's own vineyard, so it's rightly marked as a "noted vineyard", but Penfolds Grange, another of Australia's most notable wines, is not, because it's produced from a variety of different sources. Conversely, a "noted vineyard" may have little reputation at all except as a source of grapes for a well-known producer. Location is undoubtedly a hugely important factor in wine, but in the terra incognita of the brand-conscious New World, pinning down its significance is an even tougher nut to crack than in Europe.