Wine regions may lose their distinct character as grapes ripen more quickly

According to a new study, wine grapes in Australia’s south ripen on average 20 days earlier than in 1985. The researchers attribute the trend to climate changes, smaller harvests, and better technology in vineyards.

Scientists from the CSIRO and University of Melbourne who examined vintage records for ten vineyards across five regions discovered that grapes continued maturing earlier between 1946 and 2009. All but one site had this trend. Between 1985 and 2009, the trend toward earlier maturation increased.

The study included regions from Victoria, South Australia, and Western Australia.

Researchers described the change in Margaret River as “insignificant”, but only one vineyard ripened grapes later.

Nature Climate Change, an online journal, published the results of this study.

Leanne Webb is a Postdoctoral Fellow at CSIRO. She said, “Early ripening wine grapes can have negative effects on wine quality, as we’ve seen in Australia over the past few years.”

The wine industry is deeply rooted in the concept of terroir: matching grapes with unique combinations of soils and climate to produce distinctive wines. She said that global warming and changing rain patterns are altering these terroirs.

This study was designed to test the hypothesis that observed regional warming caused this earlier ripening in wine grapes. We found that regional warming was responsible for only a third (or about one-third) of the shift. “Other factors also affected the timing of grape ripening.”

These factors included declining soil water content and smaller harvests, as well as evolving management practices. Sugars from photosynthesis will be more quickly distributed into smaller grape tissues, resulting in a faster maturation of small crops.

The management practices that had changed in Australian vineyards since the 1980s, including trellising and irrigation, pruning and better nutrition, as well as improved disease and pest control, had likely also contributed. The report stated that “many of these practices improved the health and photosynthesis capacity of the vine, possibly inadvertently resulting in earlier maturity.”

These measures, however, would be costly. Wine producers could counter the trend of early ripening with new varieties and artificial shading to reduce temperatures. Researchers suggested that it would be more practical to increase irrigation, use mulch, or reduce pruning to increase crop yield.

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