I've been looking out for the Italian licence plates, but haven't seen any round here yet.

Some 170,000 Sangiovese vines are heading for my home départment of Hérault: a small army of vinous centurions in sun-reflecting helmets. I’m getting ready to make them welcome.

My suspicion is that this will be just one step in a gigantic transmigration of varieties which, supposing that humans are still walking the planet in 50,000 years, will see the existing varietal plantings we are familiar with changed utterly.

I spent much of 2009 visiting Australian wine regions, and what struck me then was that some of the existing varietal plantings in the warmer regions were reaching the limits of their usefulness. Anyone who suggests that Shiraz and Barossa may not be an ideal combination is bound to cop some flak, and if the region was still mainly producing fortified wines it probably wouldn’t matter.

The fact is, though, that if the raw materials require heavy acid correction to achieve stability as dry(ish) table wines in vintage after vintage, then the vineyard is giving you a message which it would be unwise to ignore forever. “Please,” it’s saying, “find me a later-ripening variety which can be harvested in a naturally balanced state.” That, after all, is the basis of fine-winemaking worldwide.

I’m now based in the Languedoc, and the message is much the same here. The cooler, higher zones of the Languedoc (like the cooler, higher zones of Australia) produce fine Syrah: as scented as anything in the Northern Rhône, yet in a different aromatic register, full of citrus blossom seduction as well as the widely loved thyme-and-rosemary wildness.

Yet much Syrah in the Languedoc, particularly from lower-lying sites, is often just too ripe. It doesn’t, as in Australia, get corrected into an unnatural rectitude; it just makes a skulking brontosaurus of a wine with a troublesome present and a short and dangerous future. Even Grenache seems to reach its limits in some sites here.

Mourvèdre, by contrast, is helpfully late-ripening, though it takes skill to get the best out of it (look out for La Pèira’s alluring Matassat, luscious, meaty and essence-like, when it’s eventually released). Carignan can take the heat, but its bitter edge and natural asperity will never make it a crowd-pleaser.

The Languedoc, in sum, needs to be trialling Sangiovese – and why not Aglianico, Nero d’Avola, Primitivo, Negroamaro, Sciacarello, Xynomavro, Touriga Nacional and Saperavi, too? Indeed every established, high-quality wine region in the world needs to be thinking about what it might plant in order not to sacrifice its qualitative advantages in a rapidly warming climate. That might indeed mean Syrah – for Beaujolais.

Just a glance at the gnarled, knotty intricacies of some of the magnificent own-rooted, old-vine Shiraz in the Barossa, and a thought for the crises which those vines have withstood, will underline the fact that these decisions are tough ones.

Even if your vines are only 50 years old, replanting means economic hardship and no little emotional grief, too. Since the process is an experimental one, and since the terroir equation is so complex as to resist prediction, it’s best to assume that you won’t get it right first time.

That, though, is the way in which evolution works. Whatever is least well-adapted gets wasted. The thought that this might one day mean Merlot in Pétrus or Pinot Noir in La Tâche is a tragic one. We still need to think it.

Written by Andrew Jefford