A climate of change

The recent news reports about the drastic effects of global warming on the world’s vineyards had a ring of Armageddon to them. But winegrowers in Australia’s warmer wine regions aren’t planning to sell up and move to Tasmania just yet.

The report, published in the journal “Proceedings of the National Academy of Sciences of the USA”, warned that wine output of the world’s finest wine regions could fall by two-thirds by 2050. Bordeaux, Tuscany and California’s Napa Valley would be hard hit, it said. In the worst-case scenario, Australian production could drop by 75 per cent by 2050. It further speculated that future viticulture could extend to places previously thought unsuitable, such as Tasmania. If the writers didn’t know Tasmania has long had a thriving wine industry, you’d have to wonder about the thoroughness of their research.

In fact, Australian winemakers have for some years been taking steps to counter climate change in their vineyards, which is causing grapes to ripen earlier than ever, thanks to hotter, drier seasons. These steps include site selection, grape variety selection, canopy management and soil and water management.

Viticulturist Mark Walpole, a partner in Heathcote’s Greenstone vineyard, who is involved in several Victorian regions, thinks it’s alarmist to say that viticulture will be finished in some regions by such-and-such a year. The study seems to overlook the possibility of changing grape varieties for a start. If Coonawarra becomes too hot for cabernet, for instance, it might find its future in later-ripening vines like grenache and mourvedre, which need more heat than cabernet and thrive in drier conditions.

Walpole has tempranillo in his vineyard at Beechworth, and a very good wine was made by Adrian Rodda in 2011. Beechworth is more noted for chardonnay, but Walpole says it has the temperature regime of Rioja and the sunlight hours of Ribera del Duero – Spain’s two greatest tempranillo regions. “I think we need to look more at the strength of the site and the terroir,” he says. “In Heathcote in 2009 I could smell the grapes cooking in the vineyard. It was so hot that I couldn’t believe anything could be made, but we are very happy with our ‘09s, which have lovely spice and elegance.” He said 2013 was also hot, but again the wines are very pleasing. “The mean January temperature in Wangaratta in January was three degrees hotter than average, and the heat summation of the growing season was probably 200 degree days hotter than average, but we’re very happy with the results.”

He points out that when the Greenstone Heathcote vineyard was planted, he took the unusual step of orientating the rows east-west rather than the usual north-south. This means the sun passes along the rows and there’s no direct heating of the bunches. With north-south rows, the afternoon sun heats the western side of the vine and cooks the fruit. “The heat denatures the enzymes and you lose your colour.” It also damages the grapes’ aromatic components.

Some growers address the afternoon sun problem with canopy management: they leave more foliage on the west side to shade the bunches, while they leaf-pluck or raise the foliage to expose the grapes on the eastern side.

Prue Henschke is a big fan of mulching and inter-row grassing as two ways of cooling the soil and helping moisture retention. Mulching has many benefits including encouraging earthworms. The opposite would be ‘nuking’ the weeds with expensive herbicide which leaves the earth flat, hard, hot and lifeless. Or ploughing, which disturbs the soil structure. Prue Henschke says mulching can preserve the topsoil moisture for four to six weeks longer in December-January. Inter-row grasses add organic matter to the soil, help rainwater penetration and encourage biological life. Henschke is experimenting with native plants, which need less water than the usual vineyard cover-crops.

Lethbridge vineyard in the Geelong region has had great success with mulching, but it’s not only boutique vineyards in cooler climes: Taylor’s at Clare mulches 20 per cent of its 500 hectares of vines, using either straw or suburban green waste.

Even moving your vineyard from the north side of the hill to the south can have a big effect on the micro-climate of the vine. One of the first to do this was Rick Kinzbrunner at Giaconda. In 2005 he began a gradual process of ‘shifting things around’ in response to hotter seasons. First, he removed some of his pinot noir and planted chardonnay, the reasoning being the pinot wasn’t performing whereas chardonnay performs well everywhere in his vineyard. Then he removed all of his cabernet, which was in the coolest part of the vineyard, and replaced it with pinot. Kinzbrunner’s latest act to counter climate-warming was to buy a higher, cooler block of land east of Beechworth and plant it to nebbiolo. He has plenty of land there and could plant other varieties there in future.

Changing grape varieties is the easiest way to combat climate warming. Some varieties need more heat than others, eg. Rhone Valley grapes shiraz, grenache, mourvedre, marsanne, roussanne and viognier. And they ripen later, after the extreme heat of summer has passed – which is a plus for quality. Taylors’ CEO Mitchell Taylor says his company is now producing tempranillo, vermentino and grenache, all warm-climate varieties. The first two are new to Clare.

In the Barossa, which is a warm climate – and getting significantly warmer and drier – we are seeing more Rhone varieties. Shiraz was always big, so too grenache and mourvedre, but there are some superb Rhone-style whites now, such as Torbreck’s The Steading Blanc (a marsanne, viognier, roussanne blend – tastings), Spinifex Lola (a blend of Mediterranean varieties – tastings) and Fleur roussanne, and Turkey Flat Butcher’s Block (a marsanne, viognier, roussanne – tastings). There are others. These blends, now being made with less oak, less alcohol and more restraint, have a great future. The drawback is in marketing them: blends are harder to sell than varietals and they will need to be promoted well.


Tasmania is one of the places viticulture is predicted to boom because of global warming. So why is Brown Brothers selling one of its three Tasmanian vineyards? There seems no cause for alarm – it acquired the state’s three largest vineyards when it bought Tamar Ridge in 2010 so it can afford to get rid of the smallest. CEO Roland Wahlquist said Browns intended to sell the White Hills vineyard at Relbia, although it hadn’t yet placed it on the market. “We’re in no hurry. We’re not looking for a quick sale. We want someone who’ll love it – partly because we want to buy good fruit back.” Wahlquist says Browns had never been in the business of contract growing grapes for other people, and the vineyard was surplus to its needs. It will retain the Coombend vineyard on the East Coast and the Kayena vineyard in the Tamar Valley.

Ironically, Treasury declared in the same week that it wanted to buy or lease vineyards in Tasmania, as insurance against climate warming. “They’re not very good poker players,” quipped Wahlquist. He said Treasury’s David Dearie had already called, but nothing had been decided. The three vineyards Brown Brothers acquired from Gunns total 400 hectares and represent 25 per cent of Tasmania’s plantings.


First published in the Sydney Morning Herald, Good Food – 23 April 2013.

 

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