An even better question may be: “Other than terroirs in Germany (and, heck, let’s exclude Alsace, too), which terroir do you think has the greatest potential to produce world-class Riesling grapes?”
As you may know I am intimately involved in Washington State producing Eroica Riesling as a joint venture together with Chateaux Ste Michelle, and I think the success alone of this region in terms of Riesling may answer this question for me, but in addition to the success I can speak personally to the quality of the grapes going into the wines. Plus there is a diversity from dry to sweet to even the equivalent of a TBA there so it reminds me of Germany in that respect. Of course on a small scale other places in the world can produce world-class Rieslings within their given microclimates and skill of the individual winemaker. As the climate of the world changes this will make things even more complex.
Dr Loosen, as a follow on question, can you make any comments about Riesling in Oregon?
Speaking personally, I have had two vintages of Eroica and found them (and all Washington rieslings I’ve had) very good for the price. That being said, the only regions outside of Germany (and I must include Nahe with Mosel) that have cracked my personal 90 point threshold have been the Finger Lakes and Alsace. I can count on one hand the number of OR/Australian rieslings I’ve had and while both are on my short list of regions to explore more in-depth from a riesling standpoint, overall I feel the Mosel/Nahe produce the most consistent top quality rieslings.