Keeping a cool head in a warming climate

The Australian ‘Black Summer’ of 2019/20, which saw bushfires destroy swathes of vineyard land across the country was a dramatic reminder of the growing challenges facing winemakers around the world. We spoke to leading Australian winemakers and lab technicians to find out how agile decision-making is helping to deal with the consequences of global warming.

By Wine writer, Lucy Shaw. https://www.fossanalytics.com/

Wednesday, January 24, 2024

Offering alarming proof of the escalating effects of climate change, in November 2019 bushfires blazed through New South Wales, scorching more than five million hectares of land following Australia’s hottest and driest year on record. In December 2019, the fires swept through the Adelaide Hills, destroying 650 ha of vines in the region, and wiping out entire vineyards. Making matters worse, the smoke from the fires was far-reaching, rendering vineyard plots from Canberra to the Hunter Valley useless. Ravaging an estimated 24.3 million hectares of land in total and destroying over 3,000 buildings, the September 2019 to March 2020 bushfire season – Australia’s costliest natural disaster in history – became known as the ‘Black Summer’ due to the size, intensity and duration of the wildfires, which were caused by exceptionally dry conditions in the country. 

Fire and smoke damage 

Over 1,500 hectares of vineyards were destroyed by the wildfires, with the majority of the damage concentrated in the Adelaide Hills, Kangaroo Island, Tumbarumba and parts of northeastern Victoria. Among the producers worst hit was Vinteloper in the Adelaide Hills, which lost 95% of the vines planted at its 30 ha property. Owner David Bowley’s home was also destroyed in the blaze.One of Australia’s most revered wine estates, Henschke, also suffered damage from the fires, losing 95% of the crop at its 25 ha Lenswood vineyard in the Adelaide Hills, along with two sheds and vineyard equipment. Among the losses at Lenswood were some of the oldest Pinot Noir vines in the Adelaide Hills region, which were planted by Tim Knappstein in 1983. At the time the fires hit Chardonnay and Pinot grapes were still hanging on the vines, but the levels of smoke taint were so high that owners Stephen and Prue Henschke abandoned hope of picking a single grape, leading to yield losses of 70% across the board. 

While the havoc wreaked on the Adelaide Hills was brutal, it didn’t have a huge impact on the 2020 output of the Australian wine industry at large, as the region only accounts for 1% of the country’s total wine production and 1% of its exports in terms of value. The engine room of Australian wine production – the Riverland – emerged relatively unharmed, so in volume terms, the damage from the fires was minimal. The bigger problem facing producers was smoke taint, which was far wider-reaching than the fires, leading a number of top producers to scrap their 2020 vintages altogether, or produce a fraction of their usual output. The first vintage affected by smoke taint on a major scale since 1969, Wine Australia estimated that the combination of fire and smoke damage amounted to losses of around 4% of the country’s average tonnage – around 60,000 tonnes of grapes – in 2020. High levels of smoke taint forced Tim Kirk, chief winemaker and CEO of Canberra estate Clonakilla, to abandon the 2020 vintage entirely for the first time in the winery’s 49-year history. “Once the grapes were ripe enough we began sending samples off for testing. The results confirmed our worst fears: highly elevated levels of smoke taint. At that point we had no other choice than to write off the vintage,” Kirk says – a decision that cost the estate “multiple millions of dollars”. 

Strategies for a hot climate

Helping Kirk in his hour of need was Yalumba’s chief winemaker, Louisa Rose, who offered him some of her Eden Valley Viognier and Shiraz. To protect her own vines in the fight against global warming, Rose has grasses growing between the vines and mulch to cool down the soils and preserve moisture, while canopies help protect the grapes from direct sun and trellising provides shading and keeps the grapes cooler, helping them to ripen more slowly. When things get really hot, Rose applies a fine layer of white clay called kaolin on her grapes, which acts like sunscreen, mixing it with water and spraying it on the vines to stop tissue damage from excessive heat, which is proving an effective way of maintaining acidity in the grapes and slowing down the ripening process.

Rose admits that when it comes to bushfires, there is very little that wineries can do to protect themselves in the event of one breaking out. “If there’s a bushfire next door to you there’s not much you can do about it, but a lot of research has been done in Australia around early detection of smoke taint, which impacts on picking and bottling decisions. You could turn your Pinot into a sparkling wine, for example, as there’s no need for skin contact that way,” she says. From a quality assurance point of view, using a FOSS WineScan™analyzer enables Rose and her team to make quick and informed picking decisions. “It’s great to have that ease and breadth of analysis at a minute’s notice, which helps us with decisions around analytics. Winemakers make decisions on how a grape tastes, but it’s all about balance, and the numbers are really important to back up the decisions we make with our palates,” she says. 

Chester Osborn, the charismatic chief winemaker at d’Arenberg in McLaren Vale, has various tricks up his sleeve when it comes to mitigating the effects of rising temperatures, from water management and canopy protection to composting and keeping nitrogen levels in the soil low in order to produce thicker and more resilient grape skins and a firmer pulp. He’s also rethinking his plantings to incorporate more heat-resistant varieties. “We’ve been working with hotter climate varieties for some time now from Spain, Italy, Portugal and the South of France. I’m very happy with how well these grapes grow in McLaren Vale,” he says. Among them are French varieties Carignan and Cinsault, Italian grapes Sangiovese and Sagrantino, and Spanish natives Graciano and Mencía, which are “producing solid, strong berries with good colour”, and, according to Osborn, “could be a replacement for Shiraz down the track”. When it comes to heat-resistant whites, Osborn is seeing success with Rhône trio Marsanne, Roussanne and Viognier, while he believes Italian white Fiano is “extremely well suited to McLaren Vale – perhaps even better suited than its homeland of Campania.” 

Protecting quality 
Prioritising quality over profit during the Black Summer of 2020 was Hunter Valley-based Tyrrell’s, which slashed its 2020 crop by 80% due to high levels of smoke taint, amounting to AU $3.5m in sales losses. “From mid-October we had bushfire smoke across various parts of the valley. We went through a series of tests for smoke taint with the Australian Wine Research Institute, and, based on the results, we made the decision to not pick anything that was over the recommended limits – around 80% of our crop,” says owner Bruce Tyrrell, who believes producers that allowed smoke-tainted wines from the 2020 vintage to enter the market risked damaging their neighbours’ reputations.

Frustratingly, Tyrrell reveals, there is no way to protect against smoke taint. “Grape selection is impossible because there is no way of determining it on a berry-by-berry basis. We have learnt to reduce smoke taint by about 50% with some fairly brutal processes in the winery, which means we can make decent commercial wine but no top-end wine,” he says. And while smoke taint analysis has improved dramatically in recent years, by the time you receive the results, the damage has already been done. “Smoke taint analysis is very good at the moment, however it only tells you what you’ve got when it’s too late,” says Tyrrell. “Sometimes it can take three years or more for smoke taint to show up on the nose or the palate of a wine. Luckily, we have the ability to test for the relevant compound and that can stop you spending money on a vineyard that’s never going to be any good.” 

Climate change has meant increased flooding and high rainfall, as well as hailstorms and high winds during flowering and fruit set

While making quality reds from smoke taint-affected grapes is almost impossible, whites and rosés are less impacted due to their different production methods. “You will never make fine reds from smoke-affected fruit, but some of the carbon products available did a good job with commercial whites and rosés in 2020 – we saw no bitterness in these wines and they sold very quickly,” reveals Steve Webber, chief winemaker at De Bortoli, who said careful pressings were paramount on whites and rosés in 2020. “There are certain enzymes that you can add to smoke tainted juice that can ‘cleave’ some of the smoky characters such as guaiacol, which are tied to grape sugars and subsequently can be removed more easily with activated carbon,” Webber adds.

One of the problems facing wineries blighted by bushfires is the cost of smoke taint analysis, which usually has to be outsourced. “Sensory analysis plays an important role in detecting smoke taint, but smoke taint precursor compounds are glycosylated and don’t have aroma or taste, so you don’t get a full idea of the potential scale of a problem,” says Jill Huckel-Hicks, a laboratory supervisor at Angove Family Winemakers in McLaren Vale. “Chemical analysis can now detect these compounds, but this requires expensive equipment and for most wineries this testing needs to be outsourced, which can become a costly exercise with a lengthy timeframe for results.” While there are currently no ways to protect against smoke taint in the vineyard, Huckel-Hicks points out that scrupulous harvesting, juice preparation and lab analysis can all help with managing smoke taint in wine. 

DROUGHT

It appears that the 2019/20 Australian bushfires were a warning of more challenges to come for the global wine industry. In 2022, many wine making regions across Europe saw heatwaves and extremely low rainfall

SMOKE

A helicopter battles a bushfire. It can take three years or more for smoke taint to show up on the nose or the palate of a wine

FIRE

While the havoc wreaked on the Adelaide Hills was brutal, it didn’t have a huge impact on the 2020 output of the Australian wine industry at large, as the region only accounts for 1% of the country’s total wine production and 1% of its exports in terms of value

FLOODS

More than heat in vineyards around the world, climate change has meant increased flooding and high rainfall, as well as hailstorms and high winds during flowering and fruit set

More than a heat spike 
While the recent wildfires have had devastating consequences, Angove’s chief winemaker, Tony Ingle, stresses that the effects of climate change aren’t limited to heat spikes. “It’s important to consider climate change as more than just an increase in average temperatures. It’s easy to look at the recent bushfires and record high temperatures and consider that’s the whole story then gear our reaction to these consequences, when we need to look at many other issues,” he says. “Climate change has meant increased flooding and high rainfall, as well as hailstorms and high winds during flowering and fruit set, so solely looking at heat can’t help us ride out changes in climate.” For Angove, taking a holistic approach and adopting organic viticulture and regenerative farming has helped to produce more resilient vines that cope better with the various climate challenges thrown at them. 

Importance of analysis and early detection  
Dr Eric Wilkes, general manager of Affinity Labs, which offers a comprehensive range of advanced analytical services for the drinks industry, reveals that smoke taint analysis has got to such a level now that it can effectively detect smoke taint in finished wines. “Smoke taint analysis is an area of ongoing research, however we’re quite confident that our current testing gives a good indication of the risks of smoke impacts being evident in the final product,” he says. “Much of the advances in recent times have been around understanding the levels of the compounds that are tested that lead to discernible impacts in the final product. It has to be remembered that the compounds we’re testing are naturally occurring within the grapes at some level, and so an understanding of what the base natural levels are is incredibly important to the assessment of risk.” 

With bushfires proving increasingly problematic in Australia, Wilkes and his team have seen a rise in interest for their smoke taint testing services in recent years, “and a much greater awareness of the potential for smoke events to have an impact on final wine quality”, he says. Wilkes calls upon the FOSS WineScan on a daily basis when analysing various parameters in wines for his clients. “It’s an integral tool in our support of the wine industry and its producers. While it’s not directly involved in the analysis of smoke markers, the data it produces is incredibly important towards wine analysis, and contributes to the overall production of high quality wines in the face of climate change,” he says. 

Looking ahead, Wilkes believes investment in R&D will be paramount for the Australian wine industry in order to safeguard its future. “Wineries need to continue to invest in research and development to better understand the impacts of fire events and how to mitigate those when they happen, as it’s very unlikely that we’ll see a decrease in such events invent the future,” he says. Steve Webber of De Bortoli, meanwhile, believes wineries should be factoring the effects of wildfires and smoke taint into their business strategies. “We need to factor in a vintage write-off every so often into our planning and pricing,” he says. “We have to do the same with poor flowering conditions in our cooler climates.” 

Chester Osborn of d’Arenberg would like to see the Australian government ploughing more funds and resources into early bushfire detection. “People in helicopters and planes that can detect and put out fires before they become out of control could massively assist in reducing losses in hard to reach areas,” he says. Whatever the future holds, rising temperatures and increasing incidents of bushfires across Australia are a sad inevitability of global warming, meaning a nimble approach to both grape growing and winemaking is key if producers want to stay one step ahead in the ongoing fight against climate change.