Winegrapes and Climate Change

What’s changing?

Many things. But most notably harvest dates have advanced at least 2-3 weeks since the 1980s. Today many regions that were, for example, harvesting in mid-October regularly before warming are now often harvesting in mid to late September. And the trend appears to be continuing, in recent years in France the harvest has been 6 weeks earlier than average in some areas. There are many downstream effects of this: changes in wine quality, increasing alcohol content and more.

What will determine how a region fares in the future?

Lots of reports suggest the downfall of some regions and the rise of other regions, but it’s actually much more complicated. We believe three major things will determine the future for a winegrowing region:

    1. Current climate in a region — Where within the global range of winegrowing is the region? Areas at the hotter edges (at the limits, effectively) of winegrowing will have fewer options of how to cope with warming, while areas at the cooler edges will be able to grow a greater diversity of grape varieties than they currently can (as currently their climates are too cool to mature many varieties).
    2. Expected warming and other climate shifts — climate change is highly uneven. Northern areas, higher elevations and continental regions generally warm more (Europe is 50% ahead of the global average, for example). Other factors matter a lot also. For example, changes in storm patterns or frost dates. For a region such as Sonoma a big question is how fog patterns off the bay will change. 
    3. How much a region is willing to change growing practices — growers (and regions) that are willing to be flexible, try different management strategies and plant trial blocks for new-to-them varieties now should fare better. Growers who do nothing we expect will see large negative impacts, growers who respond actively and proactively will cope much better.

Climate change is a big challenge to agriculture. It forces growers to be even more flexible and adaptable. Using more winegrape varieties may offer that needed adaptability, up to a point. With continued warming it may be hard to continue growing grapes in some regions.

What do we need to know?

How much will it warm in the future? 

The biggest uncertainty for researchers like us and growers is what emissions scenario we end up on: will the globe warm 2˚ C or 4˚ C? All of us have tremendous control over that answer and it’s critical to what the future of wine looks like. A global decision on where we’re headed for emissions would make planning and mitigating negative impacts on winegrowing much more tractable.  

We also need to know more about how particular regions will warm. Winegrowing regions are chosen for their microclimatic complexity, so knowing how a region will warm and shift climatically requires fine-scale analyses. We’re funded currently to look at this for the Okanagan in British Columbia but can help with analyses for other regions, please contact us. 

How much diversity is out there? 

We still don’t know how many grapes are planted today globally or how many are housed across all research collections, such as Domaine de Vassal, USDA Clonal Germplasms, in Georgia, Spain, and Italy (to name a few). 

What is different about different winegrapes? 

For climate change, we critically need to know the different phenologies of winegrape varieties, their heat and drought tolerances, how they respond to different trellis and irrigation strategies, how they work with different rootstocks, and more. Remarkably we have very little of this information for more than just a couple dozen varieties.