A climate of change

Recent news reports about the 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 and move to Tasmania just yet.

The report, published in the journal Proceedings of the National Academy of Sciences of the USA, warns that wine output of the world's finest wine regions could fall by two-thirds by 2050. Bordeaux, Tuscany and the Napa Valley in California will be hard-hit, it says. In the worst case, Australian production could drop by nearly 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 would have to wonder about the thoroughness of their research.

Australian winemakers have, for some years, been taking steps to counter climate change in their vineyards, which is causing grapes to ripen earlier 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 and who is involved in several Victorian regions, thinks it's alarmist to say 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 such as grenache and mourvedre, which need more heat than cabernet and thrive in drier conditions.

Walpole has tempranillo in his vineyard at Beechworth in north-eastern Victoria, 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,'' Walpole 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 says 2013 was also hot, but again the wines are very pleasing. ''The mean January temperature in Wangaratta 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.''

When the Greenstone Heathcote vineyard was planted, Walpole took the unusual step of orienting 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 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. Inter-row grasses add organic matter to the soil and help rainwater penetration. Henschke also experiments 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 that are on board. Taylors, at Clare Valley, mulches 20 per cent of its 500 hectares of vines, using straw or suburban green waste.

Even moving a vineyard can have a big effect on the microclimate. One of the first to do this was Rick Kinzbrunner at Giaconda, near Beechworth. 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 while 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 has now bought a higher, cooler block of land east of Beechworth and planted it to nebbiolo.

Changing grape varieties is the easiest way to combat climate warming. Some varieties need more heat than others, such as Rhone Valley grapes shiraz, grenache, mourvedre, marsanne, roussanne and viognier. They ripen later, after the extreme heat of summer has passed - a plus for quality. Taylors chief executive Mitchell Taylor says his company now produces 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, as were grenache and mourvedre, but there are some Rhone-style whites now, such as Torbreck's The Steading Blanc (a marsanne, viognier, roussanne blend), Spinifex's Lola (a blend of Mediterranean varieties) and fleur roussanne, and Turkey Flat Butcher's Block (a marsanne, viognier, roussanne). There are others.

These blends, made with less oak, less alcohol and more restraint, have a great future. The drawback is that blends are harder to sell than varietals and they will need to be promoted well.

Heat is on in Tasmania

Tasmanian 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 Gunns' Tamar Ridge in 2010, so it can afford to get rid of the smallest.

Chief executive Roland Wahlquist says Browns intends to sell the White Hills vineyard at Relbia, although it hasn't yet placed it on the market. ''We're in no hurry,'' he says. ''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 has never been in the business of contract-growing grapes for other people, and the vineyard is surplus to its needs. It will retain the Coombend vineyard on the east coast and the Kayena vineyard in the Tamar Valley.

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