CSIRO climate change scientist and wine expert Leanne Webb examined ripening times across Australia and found grapes were maturing faster in recent warmer temperatures, affecting quality and taste.
Some growers say they are already modifying their winemaking to cope with the effects and at least one major player is taking steps to move production further south.
“All my modelling is showing that if the climate warms up – given that a variety is able to ripen well in a region in a present climate – the actual quality that we see will be decreasing,” Dr Webb said.
“(Wine drinkers) may not understand the complexity that goes into it, but I am sure they can taste the difference.”
The CSIRO predicts temperature rises of between 0.3C and 1.7C by 2030 and while in some colder climates this can lead to more consistent vintages – like for Riesling in the Mosel region of Germany – in Australia the effect is generally negative.
Dr Webb and her co-authors found the average ripening creep had quickened to 1.7 days a year in the period 1993 to 2009 compared to 0.8 days a year from 1985 to 2009.
Of 44 blocks of vines across the dozen regions studied, only one – in Western Australia’s Margaret River – bucked the trend towards earlier ripening.
Dr Webb believes it is the temperature changes combined with some vineyard management practices that are causing the effect and while all regions will have to adapt it will be harder for the warmer zones.
“Regions like the Riverina and … the Murray Valley for instance will be more affected than regions like Coonawarra,” she said.
Brown Brothers Wineries CEO Ross Brown said he was sufficiently alarmed by climate change to have started relocating production of cooler varieties to Tasmania’s Tamar Ridge winery.
“Basically we are in the coolest part of Victoria (for wine) and that won’t be cool enough to produce some of our main wines – for sparkling and pinot noir,” Mr Brown said.
“As the vineyards warm up a few degrees some of the varieties we are currently growing won’t be viable in those vineyards in 10 to 15 years time.”
Mr Brown said warming also presented a major challenge for wines that are suited to warm climates – like shiraz and cabernet – which would lose quality.
“In a warmer climate that heat and earlier ripening period creates richer and fuller bodied wines,” he said. “But we are seeing a consumer demand for finer wines, more elegant wines and that does not augur well for people who are already making those rich fuller bodied wines.”
The makers of perhaps Australia’s most iconic wine – Penfolds Grange – have already started making adjustments for climate change.
Climate change wines
“We have seen vintages ripening earlier by a day, to a day and a half, per year for the last 15 years so we know this is happening,” said Treasury Wines regional sustainability manager Jioia Small.
Ms Small said Treasury – which also has labels like Lindemans, Wolf Blass, Yellowglen, Rosemount Estate and Seppelt – was working with the South Australian Government growing vines in controlled warming experiments and adjusting their winemaking accordingly.
While the results from these “climate change wines” were not yet available she said the company’s main issue was with any increase in extreme weather events like droughts and floods which are harder to plan for.
Victorian Wine Industry Association chair Chris Pfeiffer, who grows grapes for pinot noir, chardonnay and muscat at Rutherglen in northeast Victoria, agreed it was not just slowly increasing average temperatures which threatened growers.
“There was an expectation that this year the vintage would be more normal after years of hot weather,” Mr Pfeiffer said. “But the events (high rainfall and flooding) created a lot of problems for this industry – people had trouble just getting fruit to ripen.”
However, not all believe changing temperatures will be bad for the industry.
Natural resources manager for national wine industry body Wine Makers Australia Jonathon Green said some grapes could actually improve with the change.
“It’s not necessarily bad and probably depends on the region and variety,” Mr Green said.
“The events like last year’s flooding in parts of the country and previous years of drought are already hazards in the agricultural sector. Responding to those challenges is a normal part of any primary producer’s challenges.”