Where There Is Fire, There Is Smoke

By Doug Frost / 17 Sep, 2022

“Chinese hoax!”, a now disgraced American ex-president insisted when confronted with the question of climate change. Small solace that his post-presidential palace may soon be underwater like much of the state of Florida, one of the more predictable impacts of climate change. Yet answers will be required of the wine industry confronted by the specter of soaring temperatures, extreme weather events and altered growth cycles.

The wine press is awash in musings as to which grapes and regions will become obsolete. Some regions are choosing, like Bordeaux, to open up the grape options. But the most immediate crisis might be the precipitous increase in wildfires in areas that once enjoyed wetter climes. Though those might seem somewhat limited to the destruction of homes, buildings and only occasionally vineyards, vines not immediately in the path of conflagrations are suffering mightily from smoke damage.

The problem of smoke impact upon grapes and wines is still too new for the industry to fully comprehend. Undoubtedly, leading the charge has been the AWRI (Australian Wine Research Institute), but then the country Down Under was first to see the blazes, literal and figurative, on the horizon. Australia has struggled with water issues, drought and bushfires for more than a century; Europe has more often fought against rain and humidity pressures.

But all that has changed. Summers 2021 and 2022 have seen death and destruction in Europe, from ill-timed rain, frost, floods and hailstones larger than a man’s fist. In 2021, a heat dome brought temperatures over 40 degrees C to the Pacific Northwest, including Canada’s favored western wine regions. The 2020 season on America’s West Coast was, like years before, marked by deadly fires but more of them, more widespread and earlier in the season than has ever been seen in the country’s recorded history. Though only a handful of vineyards were damaged and destroyed, the Glass Fire alone (one of nearly hundreds of fires in California) wiped out 1555 homes and buildings, ravaging over 27,000 hectares in Napa and Sonoma.

And what was not ruined by fire was wrecked by smoke. Prominent wineries such as Shafer Vineyards bottled no wine in 2020. Napa’s legendary 2022 Premiere auction had only 21 Cabernets from 2020 on auction, a fifth of the normal collection. Famed winemaker Heidi Peterson Barrett rather publicly quit her 20-year gig as winemaker at Napa 's Kenzo Estate when the owners insisted upon releasing the winery's 2020 reds.

Such disagreements are rife when wines are smoke-damaged. Vexingly, wines will often seem only mildly affected during or after fermentation. Indeed, the true extent of the smoky, bitter, charcoal, ashtray-laden flavors can take months or longer to show up, often after the wines are already in bottle. And the severity depends upon factors that are little understood today.

The AWRI has identified four compounds (Guaiacol, 4-Methylguaiacol, Syringol and Cresol) it believes are the principal culprits, but readily admits that more may be involved in creating these deleterious effects. Their labs are now testing up to thirteen such compounds. In the U.S., labs have focused upon four to six primary compounds; those wineries that are more exacting have found testing sources for as many as two dozen possible suspects. Full disclosure: this author has dealt with the issue and utilizes all the tests available, despite that clarity is lacking. Indeed, the greatest hindrance to knowing how damaged your grapes might be is that the majority of the compounds are often in a bound, non-volatile and difficult-to-measure form. Measuring the volatile phenols, as the standard literature recommends, will provide a false confidence based upon temporary conditions. Post-fermentation, some of those non-volatile or bound compounds will become available, because of temperature, time or even the pH of the taster’s mouth. Not exactly a guarantee of future success.

The Australian wine industry has had more experience than any other, but there is little consensus whether treatment provides a complete cure or merely a temporary improvement. For some, treatments are less a cure than an evisceration of most of the distinctive flavors of a wine. Carbon treatment can remove smoke taint, it’s true, but removes color, aromas and flavors too. Reverse Osmosis may be less onerous but mostly pulls out the free, unbound compounds, which can be quickly replaced by those lurking bound molecules. Nature abhors a vacuum, as they say, and what was once seemingly free of smoke taint exhibits those ashtray flavors often only weeks later.

Some Australian winemakers insist that Reverse Osmosis is an effective tool, if only it is deployed quickly enough and often enough. How often? I have heard of a dozen or more treatments required to create what tastes perfectly clean and seemingly stays clean as well. Producers I know describe such multiple efforts by feel rather than analysis. Each pass with the RO machine can cost thousands of dollars; to own such a machine requires hundreds of thousands of dollars. So only large or deeply pocketed wineries are likely to go this route.

It takes experience, I am told, to get good at handling the problem with RO. Not so long ago, few wineries felt the need to become adept with the machines. But the issue of smoke taint is becoming more widespread, with little certainty of future range. The prevailing wisdom has been that the only grapes that are impacted by smoke are those that are near to harvest time (during or post veraison), and those that are closely proximitous to the fires, in a belief that only the larger compounds (those that are unlikely to drift very far) are responsible for the worst harm.

But 2020 proved the lie to that notion; in some cases, grapes were hundreds of kilometers away from the fires but sat in smoke-shrouded, nearly other world-like, conditions for days on end and were decimated. Vineyards nearly next door, but that were refreshed and cleared by coastal winds, showed little to no injury. Some grapes, such as Petit Verdot and Cabernet Franc seem more impacted by smoke than others. Why? At present, no one can say.

The incidence of fires is increasing around the world. Winemakers in California, North America’s Pacific Northwest, South America, South Africa, France, Italy, Spain and particularly Portugal, are seeing the sorts of fire events that Australian is finding frighteningly routine. How should a wine lover respond? By understanding that some areas are less impacted than others, and that some vintages will repay cellaring more than others. A smoke vintage like 2020 need not be wholly eschewed. But consumers should know which areas suffered and which did not, and if smoke takes aim at your favorite producer, ask them for an honest appraisal. The wine doesn’t necessarily need to be avoided but the clock is ticking for that wine and the sooner you drink it, the better. In all likelihood, the clock is ticking for all of us; we must address the root causes of climate change. If we are so lucky as to see such a dramatic shift in political and societal will, there may someday be little reason to write about smoke damage. Until then, buyer and earthlings, beware.