Buffering vineyards against climate change

As the planet continues to warm, many vineyards will become less viable – but diversifying crops could help mitigate the impact, an international study has predicted.

Modelling showed that global warming of two degrees Celsius would reduce the land area suitable for growing grapes by 58% – but varying and shifting cultivated grape varieties could more than halve this impact to 24%.

In a grimmer scenario, a hike of four degrees would impact a whopping 85% of wine growing regions, and crop diversification could salvage a third of that, leaving 58% unviable.

“It is widely accepted that climate change is affecting and will affect agriculture,” says Ignacio Morales-Castilla from the University of Alcalá in Spain, lead author of a paper in the journal Proceedings of the National Academy of Sciences.

 “The magnitude of the effects, however, will depend on how we adapt to climate change, so we wanted to know if, as often assumed, agricultural diversity actually increases resilience under climate change scenarios.”

Grapes were an ideal crop to analyse because they have “hyper-diversity” – with more than 1100 varieties cultivated globally under wide-ranging conditions – and long-term records held in research collections provide the required volume of data.

The research team, from Europe, Canada, New Zealand and the US, investigated 11 wine grape varieties: cabernet sauvignon, chasselas, chardonnay, garnacha, merlot, monastrell, pinot noir, riesling, sauvignon blanc, syrah and ugni lanc.

Drawing on European data from 1956 to 2015, mostly from France, they modelled each variety’s key maturation stages for budding, flowering and ripening.

They then projected where each variety would be viable from 2006 to 2100 under average temperature increases of two and four degrees compared to zero warming, using global planting data and temperature records from 1880 to 2013.

Results showed that switching varieties could lessen the damage caused by global warming, says senior author Elizabeth Wolkovich, from the University of British Columbia, Canada.

However, the impact and necessary strategies will differ between regions, and the authors acknowledge that diversifying will face legal, cultural and financial obstacles. Legislation may need to be addressed in some countries.

“Conversations in Europe have already begun about new legislation to make it easier for major regions to change the varieties they grow,” says Wolkovich. “But growers still must learn to grow these new varieties.

“That’s a big hurdle in some regions that have grown the same varieties for hundreds and hundreds of years, and they need consumers who are willing to accept different varieties from their favourite regions.”

More knowledge is also needed to develop crop resilience strategies.

“Wine grapes possess tremendous diversity, but much of that diversity is still not well-documented or used by growers globally,” says Morales-Castilla. “Adapting the results to specific regions also requires finer scale data, and more research.”

The findings have relevance for other crops, he notes, at least for temperate perennial crops with high diversity such as apples, stone fruit and berries.

Ultimately, Morales-Castilla emphasises what he considers the most powerful message from their study.

“We have the knowledge to start adapting viticulture to future climate, progressively and hopefully in a cost-effective fashion. But for this strategy to succeed, warming should be limited as much as we are capable.”

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