Some of the world's great vineyards could be destroyed by global warming. Rising temperatures also help to explain why wine is getting stronger
A couple of months ago the wine website Decanter.com reported that Randall Grahm, the maverick Californian wine maker who owns Bonny Doon Vineyard, had been scouting for land in Europe to plant vines.
Nothing particularly strange about that. But the fact that the part of Europe he was scouting was southern England confirmed for many that something quite dramatic was happening in the wine world.
Grahm's helicopter survey highlighted a number of issues, most notably fears of global warming. In recent years there has been a raft of reports on scientists' concern about the impact of rising temperatures on key wine areas, such as Burgundy and California.
If the current trend continues, scientists believe that the world could be almost two degrees warmer by the end of the century. This would be catastrophic, with the probability of all manner of disasters.
For southern England, which is already spawning a number of wineries, global warming could have an upside. But if better wine were made in unlikely places such as England, what about the hallowed grounds of, say, Burgundy, with its neat plots of Pinot Noir and Chardonnay, the raw material for some of the world's greatest wine?
If temperatures rise, would the area have to be replanted with grapes more at ease with hotter climates, such as the Grenache and Mourvèdre of southern France? Many believe that it would. It's a sobering thought.
At the moment the nascent English wine industry is dominated by Germanic whites, but that could easily have to change - meaning our children's children could be buying Chelmsford Chardonnay a century from now.
Global warming is already having an impact on alcohol levels. The hotter it gets, the harder it is to control how much alcohol wine has. Australia and Chile, two of the main sources of new-world wines, produce very few reds with less than 12 percent alcohol. The old world is going the same way.
This is a result of heat and fashion. Many drinkers' preference for "big" wines encourages producers to keep alcohol high in their search for strong flavour. Grapes obviously ripen fastest in the heat, but in order for them to mature phenolically - that is to say, gain optimum colour, aroma and tannic development - they need more time.
So wine makers are faced with the dilemma of when to harvest. The longer they leave the grapes on the vine, the greater the buildup of sugars, which in turn leads to more alcohol. But, equally, phenolic maturity is essential to making a great wine - or even a half-decent one. Hence the high alcohol levels.
So global warming is affecting the glass in your hand. This is even more apparent as 125ml glasses give way to posher, larger, more impressive bowls, such as Riedel glasses or Waterford's new range.
In theory, the larger bowl allows the same amount of wine greater opportunity to express itself, by providing more room to swish it around, but in practice you drink more. And when the wine in your glass is also more potent than it used to be, it doesn't take long to drink your weekly 21 units, if you're a man, or 14 units, if you're a woman. They can tot up very fast.