MULL THIS OVER
ACIDITY MAY BE the least appreciated essential element of wine, yet we are losing it. Acidity gives balance, liveliness, some of the elegance of wine, and helps to preserve its integrity while aging. Insufficient acidity equals boring, flabby, heavy wine that may reach senility before maturing. Progressively rising global temperatures are already reducing grape acidity, chiefly tartaric acid. Our vinous world is undergoing a tectonic shift.
It’s not only acidity. Warming may have led to a temporary euphoria occasioned by its resultant ripeness, especially in previously marginal areas – but ripeness is not all. Critical balance is being lost, as jammy fruit and alcohol concentration rise to unprecedented levels. Although some of this may be caused by vineyard and fermentation practices misconceived as catering to the tastes of consumers and critics, rising temperature is the more basic and less alterable problem. Vine-preserving and health-giving polyphenols are being affected. Even microbial flora in the vineyards are changing.
Most at risk in the near term are vineyards on the fine edge, e.g., Champagne, Mosel and a number of Loire appellations. Some may be forced to seek similar terroir in places previously unsuitable, but now warming to suit. Picture the Champenois planting in England’s chalky soil. Vineyards at the warm margins of effective viticulture are also at particular risk – watch out California, Australia and the Mediterranean littoral! It is no longer just gallows humor to discuss the vine-planting prospects of Montana. How about Alaska and Siberia?
There’s no denying that harvests in many regions occur 2 to 4 weeks, or more, earlier than they did 3O years ago, that unripe vintages have become rare, or that harvest sugars and wine/alcohol concentrations are at all-time highs. Scientific studies confirm the trend, as explained by Susan Gaidos in science news, February 8, 2O14, and documented by the research of Nikolas Bokulich, et al. in proceedings of the national academy of sciences usa, January 2O14, by Lee Hannah, et al. in that same journal April 2O13, by Nyamdorj Barnuud, et al. in international journal of biometeorology, September 2O13, by Anna Bock, et al. in plos one, July 2O13, by Marco Moriondo, et al. in climate change, March 2O13, and by Gregory Jones, et al. in climate change, 2OO5. These are just a selection of many.
A study of 17 wine regions revealed an average temperature rise of 1.26o Celsius. The climb in Mediterranean vineyards was steeper. It is projected that average temperatures will increase another two degrees by 2O49, a very large increment, reaching, in Bordeaux, the upper temperature limit for growing red varieties and exceeding the ideal limit for whites. High temperature spikes impede grape maturation. The wine production of Tuscany and other regions is predicted to fall by 7O percent. Projections have plantings moving north amid increasing heat and a shortage of water.
Not to panic! There’s still time, though not much. Maybe efforts to halt global warming will become serious, global and effective. And viticultural research is already starting: planting at different orientation or at higher altitude, development of more suitable grape varieties and finding cooler vineyards. But I would not embrace the role of vigneron – the temperature of whose holdings is already marginally high.
