Terroir Trocken

Photo credit Markus Spiske on Unsplash

The photos that German astronaut Alexander Gerst sent back from the International Space Station during summer 2018 were deeply shocking: Germany was no longer green, but brown. The only visible green in the entirety of many of the wine regions was in fact the vines. 

RIP cool climate?

While it was common knowledge that the summer of 2018 had been exceptionally warm, few people realize it was also the warmest ever recorded. The Average Growing Season Temperature (AVGST) registered at Geisenheim/Rheingau in 2018 was 17.8° Celsius, or 0.9° (1.6° on the Fahrenheit scale) above the previous record year, 1947. However, most were happy to consider that an anomaly rather than a portent of the new normal. 

Then 2019 brought another drought year. And 2020 was even worse. At the end of that string of years, Germany had an average precipitation shortfall of 340mm (almost 13.5 inches). German soils were drier than at any point in 2018, 2003 or 1976: all famously hot years. And lest you think that Germany’s recent experience was an aberration, consider how Austria experienced a broadly similar scenario in 2017-2019.

The landscape of German-speaking wine is not just browning during hot summers, it is truly drying out. 

The German-speaking wine world is famously cool climate, its wine landscapes decisively green, and historically its warmer corners have stood out in contrast to the general pattern. But the current drought pattern has become the central challenge for winegrowers throughout Germany and Austria. This is far more important than, say, recent changes to the German wine law that switch the crucial factor for assessing wine quality from grape sugar levels to place of origin.

It’s widely appreciated that regions in Mediterranean climates, such as California, Southeast Australia or most of Spain, with their hot, arid summers are perhaps most vulnerable to the growing climate emergency. Unless warming halts, each of them will hit the upper temperature limits for the latest-ripening wine grapes like Carignan, Mourvèdre, and Nero d’Avola. Push any grape above its upper temperature limit and it will lose both balance and varietal characteristics. However, what’s recently come to light is that it’s not only the warm regions that are at risk of extinction. Growing scientific evidence indicates that drought in the German-speaking wine world will lead to changes almost as dire. 

The Drought below the Surface

New, as yet unpublished, research by Marco Hofmann and Professor Hans R. Schultz at Geisenheim University shows just how rapidly the situation in most German wine regions has worsened. Their work quantifies the climatic water balance, or the difference between rainfall and the potential evaporation of water from the soil plus transpiration of water through plants. This figure is negative because actual transpiration is always less than the potential, since plants regulate their transpiration to protect themselves. In order to give a realistic measure of the amount of water in the land this is a 10-year running mean. Here are the figures for the last 15 years. (Note the new trend from 2011.)

Those numbers show that not only is there significantly less water in vineyard soils for the vines, but there’s ever less water for the entire ecosystem. The landscape of German-speaking wine is not just browning during hot summers, it is fundamentally drying out. 

In Austria, the last rainy period was the summer and fall of 2020. Austrian growers as a group heaved a collective sigh of relief when they finally saw their vineyards green again as soil water reserves were replenished. Andreas Wickhoff MW of Weingut Bründlmayer in Langenlois, Kamptal told me that as of this writing, everything has remained green and the vines are looking good. In the winegrowing regions of Germany, rainfall during the first five months of 2021 was about 200mm / 8 inches, or around 50mm / 2 inches up on the long-term average. That’s not enough to erase the deficit, because the directly measured shortfall (i.e. making no allowance for the high temperatures) in 2020 alone was around 150mm / 6 inches. However green things look right now, the problem hasn’t gone away. 

Coping with the Climate Emergency

Where are we heading? The first part of the answer is irrigation, particularly in historically dry locations. With its steep slopes and shallow, stony soils, the Rüdesheimer Berg (with the sites Schlossberg, Rottland, Roseneck, and Kaistersteinfels) at the western end of the Rheingau, is one such terroir. According to Professor Hans R. Schultz, an irrigation system plus the infrastructure to capture as much run-off water as possible will be installed there shortly. It’s hoped this will be a sustainable system only utilizing the rainwater collected on site for irrigation. On paper, this could potentially work with current winter rainfall levels, but Professor Schultz emphasises the dependence of the sustainability on that winter rainfall. 

© Stuart Pigott

Changing the grape variety is another option, though this is clearly a radical step. Some years ago the Rheingau state winery Kloster Eberbach planted two hectares in Berg Rottland with Cabernet Sauvignon (most planted in 2012, the remainder in 2018), which is much more drought resistant than Riesling. Less radical is perhaps the approach of Dr. Martin Tesch of Weingut Tesch in the Nahe town of Langenlonsheim. He is changing the row orientation from the traditional north-south to northeast-southwest, or even to east-west in his new plantings in the Krone site. 

Of course, all those things enrage traditionalists — as once upon a time so too did the idea of irrigation. They insist that irrigated vines inevitably become addicted to the irrigation water, and the roots move to where the irrigation water drips into the soil. While this argument assumes that irrigation water flows frequently, examples in Austria’s Wachau as well as neighboring Kremstal and Kamptal reveal that that is simply not the case. Large-scale irrigation systems have been in use there since 1979. Growers are limited to a maximum of six water applications per growing season. Each application must be approved by a committee that examines weather data and the state of the vineyards. This type of irregular irrigation imitates natural rainfall.

A forest behind your vineyard is a built-in water reservoir. 

Another possibility — counter-intuitive as it may sound — is to decrease the vine density. This is a path being pursued by Rheinhessen producer Daniel Wagner of the Wagner-Stempel estate in Siefersheim. In one of his parcels in the Höllberg GG site he has pulled out every second row to reduce the vine density to just under 3,000 vines per hectare. This strategy reminds me of something Stephen Henschke of the Henschke winery in South Australia’s Eden Valley told me. The original planting of the famous Hill of Grace vineyard (original name Gnadenberg, after the adjacent Lutheran church) from 1860 by Nicolaus Stanitzki was twice as dense as it is now. After a number of years he pulled out every second row. The northern European idea of ideal planting density simply failed in this radically different climate zone.  In regions with Mediterranean type climates almost nobody does dense plantings, because it gives each vine too small a volume of soil from which to draw water.

However, I believe we must look beyond the vineyards to consider the ecosystems of which they are a part, for the vines are dependent upon it as much as the winegrower’s tending of them. 

The Forest for the Trees

Almost a third of Germany is Wald (forest). And some of the highest percentages in the country occur in the major winegrowing states: 42.3% Rheinland-Pfalz (covering the wine regions Ahr, Mittelrhein, Mosel, Nahe, Pfalz, Rheinhessen), 42.3% Hessen (Rheingau and Hessische Bergstrasse), 38.4% Baden-Württemberg (Baden and Württemberg). These forests are in trouble. A recent survey found that just over a fifth (21%) of the trees in German forests have a fully intact crown, suggesting significant external stressors and an ecosystem in danger.

Photo credit Paula Redes Sidore

I live in the forested Taunus hill country above the Rheingau, and there much of the shallow-rooting spruce (Picea abies) is dead. Beech (Fagus sylvatica) are also dying in significant numbers on south-facing hillsides because this species hates direct sunlight on the trunk. And sunshine hours are also way up — in April 2020, for example, they were almost double the historic norm! Waldsterben, or forest death, is sadly typical for Germany. For example, 4.7% of all the spruce in Germany died during 2020 alone. 

In 2019 the German government promised 500 million euros to support forest replanting with more drought-resistant species. My fear is that this is too little, too late and entire landscapes in Germany and Austria will be permanently changed. The knock-on effect upon the climate would be devastating with further reduced rainfall, and the possibility of a feedback loop developing. Such developments are bound to impact winegrowing in the numerous locations where vineyards border forests.

Historically, wine experts have regarded the rivers of German-speaking wine regions as the element perhaps most responsible for the greatness of certain vineyards located on, or close to, their banks. However, while it makes for a romantic story, the reality is that the reflection from the surface of the water is almost negligible and rivers don’t warm the land close to them as is commonly supposed. The most crucial thing for terroir at 45° – 55° N is topography: exposition, inclination, altitude, along with the lay of the surrounding land. Water in the vineyard soil is far more important for wine quality than water in the rivers!

Soil water availability is greatly influenced by the presence of forests above the vineyards. Forests absorb almost all the rain that falls on them, due to the effective absence of surface runoff that, for example, sloping fields and vineyards suffer from. A forest behind your vineyard is a built-in water reservoir. 

One of the large differences (along with exposition) between the Mosel sites of Braunbeger Juffer, Juffer Sonnenuhr, and Wehlener Sonnenuhr, for example, is the swath of forest above the latter and the thin row of trees above the former, behind which lie yet more vineyards. No surprise that in hot and dry years like 2003 and 2018, the Brauneberger Juffer and Juffer Sonnenuhr tend to do less well than their Wehlener counterpart. The top sites of Brauneberg draw on far smaller water reserves than those of Wehlen.

California is the Canary in the Coal Mine

To see what might be in store for us, let’s turn to California, which famously has not only vineyards but considerable forests as well. During the 2011-17 statewide drought 163 million trees are estimated to have died, and this dead wood provided part of the “fuel” for the catastrophic 2017 and 2020 wildfires. Allied Grape Growers of California estimate that between 240,000 and 325,000 tons of wine grapes went unharvested in 2020 due to smoke taint. A proportion of what was harvested (depending on exact vineyard location and harvest date) had to be ultra-filtered to remove the smoke taint and, of course, this stripped positive aroma and flavor compounds. Much of the wine thus treated had to be sold below market value, so the loss was far greater than the straight-forward value of the unpicked fruit. 

I think it’s misleading to focus narrowly on episodes like this when the Four Horseman of the Climate Crisis (heat, drought, fires, followed by floods) ride into town. The long view is every bit as important. 

Drought will lead to chronic problems and acute crises of a kind German  winemakers have never faced before.

“From an ecosystem aspect, I don’t think our forests and our natural lands that rely on rainfall ever fully recovered from that drought and now we’re into the next one,” Doug Parker, director of the California Institute of Water Resources told the LA Times in a story published this spring. According to fresh data, the majority of California is experiencing an exceptional drought (highest level) or an extreme drought (second-highest level). 

The effects of drought on this scale are complex. For example, the Chinook salmon population in Californian waters has all but vanished since 2010. The salmon industry rightly points to the way agriculture, particularly in the Central Valley, is responsible for sucking up river waters and leaving too little for the fish. Wine is just one element in this complex picture.

Sounding the Alarm for the New Normal

Unlike many of their German-speaking colleagues, before the effect of climate change became so massive, California winegrowers were used to not only drought and irrigation, but also to fire and flood. In the German-speaking wine world, the problems created by climate change are new. We are only beginning to recognize their shape. 

The BBK Bundesamt für Bevölkerungsschutz & Katastrophenhilfe, Germany’s equivalent of the United States’ FEMA, recently issued an official warning of the environmental dangers the country might shortly face. President Armin Schuster spoke first of the problems created by the falling water table in combination with the competition for water between industry, agriculture, and private households: “At least as great is the danger of forest and other vegetation fires plus extreme changes in the weather.” The latter refers to the way floods often follow drought, as we saw so devastatingly in Australia last year. Leading to the conclusion that Germany could soon be given a taste of what happened there and in California. 

German-speaking winemakers have quickly learned to handle grapes that ripen under much warmer and drier conditions than those of their parents’ generation. The far greater challenges lie outside in the vineyards of these browning regions when drought bites ever harder. Drought will lead both to chronic problems and acute crises of a kind German-speaking winemakers have never faced before. 

Grape varieties like Austrian Grüner Veltliner that have proven themselves vulnerable to drought will literally lose ground, both in the vineyards and on shelves and lists around the world. And those vine varieties that have proved resilient, like the Austro-Hungarian Blaufränkisch will gain ground. However, these will only be the most obvious signs of a massive reorientation. Winegrowers will be forced to work on their ecosystems to make them more resilient and thereby buttress their vineyards against drought. 

My first experience of this kind of work was in 2015 at the Grosset winery in Clare Valley/South Australia and it made a deep impression upon me. By planting native species around his vineyards and changing practices in them Jeffrey Grosset has taken major steps towards protecting his vines from climate change and restoring the landscape of his region. I recommend German-speaking winemakers start to learn from examples like Jeffrey Grosset’s now. Tomorrow may be too late.   

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