Friday, March 15, 2019

Global Warming and Its effect on Wine Production


During the latest edition of Vinexpo NY, I had the pleasure of attending Dr John Holdren’s presentation “Global Climate Change and the Wine Industry: challenges and options”.
So, I must confess that I don’t do enough for mother Earth….unfortunately I’m in the group that Dr Holdren’s mentioned during his conference, climate change is not in most people’s minds, actually it is currently ranked at #17 of things that we worry about, and that has to change. If we don’t, the consequences will be catastrophic, but I will only dedicate this post to how wine production is and will be affected. Starting with Dr. Holdren forecasting that if no action is taken, by 2040, temperatures will be too hot/ high to grow grapes in countries such as Spain, Italy and France. Do we want that? Certainly not.

As I always say, a good wine is born in the vineyard, and good climate and water access are vital to get optimal fruit.  Good climate (between 60-70 F) is needed during budding, flowering, veraison (when grapes change their colors from green to yellow a purple getting closer to maturation) and ripening. Frost during budding or flowering can seriously affect yields, and hail can destroy delicate buds. Heavy rains closer to harvest can dilute fruit, acid and tannins, throwing away the work of months and create humidity that will allow fungus to wreak havoc.
Producers are very concerned about this, since most part from the fact that each vine will be productive for at least 40 years. If you plan to plant vines now, you need to consider global warming forecasts very seriously. Specially since projections for 2100 predict an increase of 2 to 2.5 ºF in the best case scenario and 8ºF, in the worst case scenario .

Of course viticultors are seeing changes right now, and you as a consumer can taste them too, there is an abundance of overripe wines in the market, those that know me and my love for acidity, know how much I hate this!

However, global warming is not a problem for everybody, there are some producers that are actually happy about it (they come from appellations with cool climates and marginal climates that in previous years strived to get grapes ripe). But now thanks to global warming, they get better fruit and with the addition of getting more sugar, they get extra alcohol that they couldn’t get before, at least naturally. Some producers also saw an increase in yields and that is something they need to keep an eye on, to keep quality.

Since 2003 we have seen/ felt extra hot summers, and that have given great vintages in several appellations (including Champagne, Bordeaux, Burgundy, the Mosel,etc), so ripening grapes is no longer a problem like it was in the past. However there are few things that producers are complaining about:

*Sugar levels are higher and acidity levels lower. Some of these however can be fixed at the winery.
*Shorter ripening seasons, with harvests dates coming earlier than ever and at least 2 weeks before previous vintages. Indeed, higher temperatures mean more sugar, but vines need time for phenolic development, if these two don’t go together, we could have high alcohol wines with green flavors. Mostly because seeds and skins ripen slower and need a long ripening season of 110 days instead of the 90 days, that they are getting right now.
Extreme temperatures both in winter and summer, with long periods of rain or drought. Hail, the size of golf balls, floods, torrential rains, strong winds and fire, as seen in California and Chile.
*Decline in diurnal and nocturnal temperature variations. This is vital to hold acidity, which disappears as temperatures go up and stay up during the day.
*Increase of fungal diseases such as mildew and peronospora, seriously affecting yields, due to high humidity.
*Botrytis arrives earlier in the season instead of late, when it is most favorable to produce botrytis affected wines (sweet styles). So, instead of concentrating sugars as botrytis should do, they concentrate high acidity and green flavors, also known as “sour rot”.
*Eiswein (dessert wine made from frozen grapes) requires low temperatures, and can’t be produced every year.
*Lack of low temperatures don’t allow vines their deserved rest during the winter, and it also doesn’t kill pests and diseases.
*Too low temperatures may cause vines to freeze and die, and this is something to keep eye on if they are planning to move vineyards in altitude.

Some producers (Torres, Catena, etc) are paying close attention to the matter and already acquiring land at high altitude. As Professor Holdren recommended during his lecture “you either move up in altitude or in latitude”. Moving up in latitude means vines are now planted in places where grapes couldn’t ripen in the past; Sweden, Northern Poland, England (where good quality sparkling wines are now produced), etc. So, in the future vine regions will eventually move out of the current latitudes 30-50º north and south respectively.

Other solutions that were reviewed at the conference:
*In an effort to delay ripening and stretch the growing season is recommended the use of special roostocks and clones. The planting at different densities, canopy management and high training of  vines can be used to delay ripening. Late pruning, which causes late budding, is also used to delay ripening.
*Used of nets to protect against sunburn caused by UV-B Radiation. Taking into account that some grapes are more delicate than others, red varieties with thick skins, tolerate warm weather better, for example Grenache and Syrah won’t be affected, but Pinot Noir is very sensitive to warm temperatures.  Canopy management and changing of vine orientations can also be used to protect fruit from excessive sunlight exposure by providing extra shade.
*Drip irrigation is recommended to counteract drought and also the use of vine clones resistant to drought. Remember, photosynthesis shuts down completely when the weather is too hot, at the same time, hot weather causes the vine to sweat in excess. Water stress though welcome in some cases, also shuts down photosynthesis, this is bad for vines that don’t have access to water basins. The use of soil cover crops may help manage drought and periods of heavy rainfall.
*Better selection of clones and grape varieties, In the past clones were chosen to produce high yields and sugar, this can be reverted, by selecting clones prone to produce lower sugar levels and higher acidity, to adapt better to warm climates.
*Uprooting of  sensitive to warm weather varieties and their replacement with warm/ hot climate varieties.

So, though there might be some clouds in the horizon, it looks the wine industry will survive after all. However our responsibility as citizens is to think in the long term and to make sure governments understand this.

Right after the conference, I had the chance to visit a group of biodynamic wineries present at the conference and would like to recommend their wines. 
The practice of biodynamics is not only good for the soils, and therefore mother earth, but also good for us, since eliminates the use of chemicals in the vineyards, unfortunately it has proven to be successful only in dry climate appellations.
My recommendations are two wines from Seresin winery in New Zealand.

Seresin Sauvignon Blanc 2017,  this wine tastes closer to a white Bordeaux, since it has a bit of Semillon in the blend and part of the blend is aged in oak, this sauvignon blanc is not very fruit forward as most coming from NZ, but more mineral. $20

Seresin Pinot Noir Leah 2016, a very elegant red featuring red fruits (cherry and strawberry) and fine tannins. $30

Cheers!
Silvina


Sources used to write this post:
Besides Dr Holdren's Presentation. I consulted the following papers:

"The Impact of Climate Change on Viticulture and Wine Quality" by paper by Cornelis van Leeuwen and Phillippe Darriet. Journal of Wine Economics, Volume 11, Number 1, 2016.

"Climate Change: Field Reports from Leading Winemakers". Journal of Wine Economics, Volume 11, Number 1, 2016

"Global change, sustainability and challenges from grape and wine production" by Hans R Schultz, 2014.