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By Karen MacNeil
December 7, 2018

Several WineSpeed readers have written in worried about the future of eiswein, one of the most spectacular sweet wines in the world—and one of the most difficult to make.

Is eiswein doomed thanks to global warming? The answer is a qualified yes. Below I interview riesling specialist (and my old friend) Johannes Selbach, winemaker and proprietor with his wife Barbara, of Selbach-Oster in the Mosel region of Germany.


KM: Given the warming Germany has experienced over the last several years due to climate change, and given the predictions for even greater warming, do you envision a possible future in which no German eiswein exists?

JS: I do not imagine a future where eiswein does not exist at all, but certainly a scenario where it will become very scarce; more a freak of Nature than something we could fairly regularly count on by the weather of the season—late fall or winter. There will still be eiswein now and then, but it will come from cooler parts of Germany (i.e. Saar and cool parts of the Nahe are more likely to succeed than Mosel).

And the rare likelihood of it happening will make eiswein production a much greater risk than, say 10 years ago (definitely a much higher risk than 20 years ago!)  Fewer and fewer producers (and that includes Selbach-Oster) may want to take that risk.  After all, the grapes need to freeze on the vine naturally, and for that you need ripe, healthy grapes and this means you can’t wait too long, before wind and weather take a serious toll on the quality of the grapes (not to mention the feathery and furry beasts that like to munch on sweet grapes during a time of the year where Nature’s table is no longer laid out in plenty).

KM: Under what conditions could eiswein’s complete disappearance happen?

JS: To make eiswein, you need to have at least minus 7 centigrade, preferably deeper, in order to fully freeze the grapes. The riper the grapes, the deeper the temperature needs to be. Now, a couple of hours of minus 7 Celsius don’t do the job. Ideally, you’d have at least 24 hours of such temperatures or lower. An old rule of thumb is that a great eiswein is possible when you have two consecutive frost nights (better yet two frost days and nights). On Day One, the grapes freeze but, on Day Two, the frost is through and through, and the grapes are frozen solid, not just like slush. This is when you can make great, concentrated eiswein.

KM: Would Germany ever consider amending the part of the law that stipulates “naturally frozen on the vine” in order to preserve eiswein as a category of German wine? (i.e. Allow eiswein to be made in commercial freezers?)

JS: I don’t think so. At least not in the foreseeable future. Germany is very conservative in the sense of making wines as pure and natural as possible. Cutting corners by freezing grapes artificially would not go over well with consumers and also with the majority of wine producers here.

KM: Although the production of eiswein might grow smaller, will the production of other styles increase? (Kabinett? Dry wines in general?)

JS: The production of the “bigger” wines has increased, and this trend is likely to continue as the temperatures stay warm or even keep rising. The whole “old” system set by the German Wine Law, i.e. the minimum ripeness standards set for the different “Pradikat” wines has been made obsolete by the warmer growing conditions. Today’s kabinett is yesteryear’s spätlese, and today’s spätlese is yesteryear’s auslese. That doesn’t mean the wines have become sweeter, but rather that the wines are more supple and generous today than their counterparts were 30 years ago. Bottomline, German wines have taken a significant step up in overall quality, and that is due in part to the changing climate and in part to the much better, “tender loving care” viticultural practices of today versus 30 [or] 40 years back.

To put this in context: in the 1970’s and 1980’s there were plenty of world-class wines—delicious, well structured, long-lived, praised by the critics—but the number of those wines has since increased significantly, and today it is not limited to the leading producers. Rather, many more producers are making very good and excellent wines although, sadly, many mainstream consumers haven’t taken notice of that fantastic development.

In the context of eiswein, I’d like to point out that the production of noble sweet wines using perfectly botrytized grapes has increased at the same rate eiswein has decreased. Today you find more super delicious, well-made beerenauslese (BA) than eiswein, and those wines offer much more complexity, more flavor, more length, and more potential than eiswein. Mind you, both BA and eiswein live from grapes losing water. Eiswein is simple: the frost freezes the water out of just about any grape, a lesser one as well as a better one. For BA, however, you need fully ripe, thin-skinned grapes and then the right temperature and moisture for botrytis cinerea to start punching micropores into the grapes’ skins, slowly dehydrating them while adding the botrytis signature flavors—honey and smokiness—to the grape.

In short, we consider eiswein the lesser of the two sweet “dessert” wines; beerenauslese definitely delivering more flavor, complexity, and nobility than eiswein. Which means to say, the loss of eiswein has been compensated for by a gain of wines with noble sweetness, courtesy of full ripeness plus botrytis, i.e. BA and certainly also trockenbeerenauslese (TBA), although the latter in much, much smaller quantities.

KM: If eiswein made from riesling is in peril because of climate change, are there other varieties that could perhaps still be used for eiswein or do all varieties require the same level of cold temperatures?

JS: All varieties need minus 7 C or lower. It is not so much the varietal but, rather, the sugar and acidity in the grapes that matter for eiswein. The sweeter the grapes, the more difficult to freeze them.

A low acidity varietal like pinot gris won’t make an exciting eiswein because pinot gris doesn’t have very much flavor and not much acidity as a grape or wine to begin with, so the concentration by freezing doesn’t yield much. Grapes with a lot of flavor and good acidity are the ideal candidates for making eiswein. In Germany—and I dare say elsewhere, sticking with noble vitis vinifera—there is no alternative to riesling which ripens late; is thick-skinned; contains less water than other, plumper grapes; and has more “yin and yang” flavor and acidity, than any other grape.

KM: In general, has climate change in Germany sometimes been beneficial?

JS: [Year] 2018 is another prime example of the changes that have been and are taking place. The weather has become warmer in general. Winters are not so cold any more (contrary to common belief in the U.S., they never really were so cold in the wine regions, which have a rather mild microclimate, provided by the sheltered river valleys), summers are hotter, spring starts earlier and more suddenly.

KM: Are some areas of Germany more affected by climate change than others?

JS: That is difficult to answer with scientific proof, but I’d say all of Germany has gotten warmer, although we certainly have great variations between regional climates within Germany. Mind you, we have a number of mountain ranges in Germany that run from East to West and that block cold air from the North. Unlike North America, we never get the “Polar Express” that comes blowing down from the Arctic. Plus, much of the western part of Germany has a maritime climate, influenced by the Atlantic Ocean and, to some extent, by the Gulf Stream. The further east you go, the more “continental” the climate gets which means Berlin will usually get much colder winters than, say, Frankfurt or Cologne.

If you look at the wine country only, it is safe to say that the northern regions of Mosel (with Saar and Ruwer), Ahr, Mittelrhein, Nahe, and parts of the Rheingau have been on the receiving end of the warming—getting riper over the years but still without losing elegance and typicity in the wines. What seems to be happening is a shift of precipitation to much drier summers. Rainfall occurs more erratically, and the volume of that rain seems to become more concentrated on fewer episodes of rainfall, causing some concerns with erosion which we did not have to deal with much 25 years ago.

Bottomline, however, we have clearly benefited from the change in climate if you compare the 1980s and before with what we have now.