Winemakers could adapt to climate change by switching grape varieties

As temperatures rise and seasons change, the regions of the world that are suitable for growing wine grapes could shrink by half or more, new research has found.

However, the losses can be mitigated to an extent if vintners swap the types of grapes they grow.

According to a study co-authored by Lincoln University, Senior Lecturer in Viticulture, Dr Amber Parker, 56 percent of the world’s winegrowing areas may no longer be suitable for producing wine if global temperatures rise by 2°C and there are no attempts to adapt.

And with 4°C of warming, suitability for winegrowing could decrease by 85 percent.

Fortunately for wine-lovers, however, the new study published in the Proceedings of the National Academy of Sciences also outlines an adaptation strategy. The findings of the study indicate that reshuffling where certain grape varieties are grown could halve the potential losses of winegrowing regions under 2°C of warming and reduces losses by a third if warming reaches 4°C.

The study indicates New Zealand is likely to remain relatively unscathed in the 2°C scenario in relation to warmer climate regions, which are already limited to planting the warmest varieties.

“New Zealand could adapt to climate change by gaining suitable grape-growing areas in regions not currently suitable, or we may be able to introduce and expand production with varieties such as Grenache and Mourvèdre, which are more suited to a warmer climate,” Dr Parker said.

Grapevines are extremely diverse, with more than 1,100 different varieties grown in a wide range of conditions, and especially sensitive to the seasonal temperature fluctuations that come with climate change. Harvesting outcomes are also well documented, as the data stretches back centuries.

“On a global scale, switching varieties could halve the potential losses of winegrowing regions under 2°C of warming and reduce losses by a third if warming reaches 4°C,” Dr Parker said.

She and her colleagues investigated whether using this wide diversity of wine grapes could help build resiliency, and their findings may help other areas of agriculture adapt to a warming world.

The researchers — led by Ignacio Morales-Castilla at the University of Alcalá in Spain and Elizabeth Wolkovich at the University of British Columbia, Vancouver — focused on 11 varieties of wine grape, based on their diversity in development timing, a key trait for climate adaptation.

They selected Cabernet sauvignon, Chasselas, Chardonnay, Grenache, Merlot, Monastrell (also known as Mourvèdre), Pinot noir, Riesling, Sauvignon blanc, Syrah and Ugni blanc.

For the 11 varieties, the team used vintner archives to build a model for when each would bud, flower, and ripen in winegrowing regions around the world under three different warming scenarios: 0, 2, and 4 degrees of warming. Then they used climate change projections to see where those varieties would be viable in the future.

Losses were unavoidable in both warming scenarios, due to shifting temperatures and seasonal changes that would affect conditions while the varieties were ripening.

These factors would affect the wines’ quality, but by changing these varieties around, losses can be significantly reduced.

If winegrowers switch to varieties more suitable for the changing climate, only 24 percent of the world’s winegrowing areas would be lost with 2°C of global warming, rather than 56 percent.

For example, in France’s Burgundy region, heat-loving Mourvèdre and Grenache could replace current varieties such as Pinot noir. In Bordeaux, Cabernet sauvignon and Merlot could be replaced with Mourvèdre.

Variety-swapping is less effective at higher levels of climate change, as indicated by the results that came from 4°C of global warming.

The researchers note that there may be legal, cultural or financial hurdles to switching wine grape varieties. They also note that management practices like using shade cloths can help to protect grapevines, but only at lower levels of warming.

Ultimately, the effectiveness of any strategy depends on growers having the options and resources to adapt at a local scale, and on reducing greenhouse gas emissions and limiting warming globally, the authors say.

Source: Lincoln University

PHOTO: Elizabeth Wolkovich

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