In December 2018, Johannes Selbach, a winemaker in Germany's Mosel region, was asked whether eiswein - a sweet German wine made from grapes that have frozen on the vine - is "doomed thanks to global warming".

His answer to the Winespeed blog, was a qualified yes.

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To make eiswein, you need to have at least minus 7 degrees Celsius, or 19 degrees Fahrenheit, to fully freeze the grapes.

"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). This is when you can make great, concentrated eiswein," Selbach said at the time.

On Sunday, the German Wine Institute said that none of the country's wine regions saw the necessary low temperature.

"Due to the mild winter, the minimum temperature of -7C required for an ice wine harvest was not reached in any German wine region," said the institute's Ernst Buscher.

"And the coming days are also no longer expected to have frosty nights."

Because of their inherently low yields, ice wines come from a very small share of the total harvest, often less than 0.1 percent.

The trend is clear: in 2013, only five producers made eiswein, in 2014 fewer still. In 2017, seven producers were successful but for the 2019 season, there will be none.

The Copernicus Climate Change Service (C3S) of the European Union has confirmed the year 2019 as second-warmest on record. In Europe specifically, 2019 was the hottest year on record. The following winter in Europe has been comparatively mild and Germany is no exception.