A delicate Yorkshire Riesling, robust Canadian Cabernet?

September 22, 2006 12:45 PM

A delicate Yorkshire Riesling, robust Canadian Cabernet? If global warming raises temperatures, an often mentioned consequence is the growing of wine grapes in the far North (for example the article in Slate today). Does this really follow?

My scepticism is based on a belief which may be wrong. The belief is that wine grapes do not flourish above 50 degrees North because the Ultra Violet rays of the sun are too weak, too diluted by the atmosphere at this latitude, to fire off the complex chemical reaction that produces sugars in the vine. A simple rise in temperature will not make any difference to this problem which would only be solved if the sun were to become brighter (which it will not).

Further a blanket of atmospheric carbon dioxide, which will cause the rise in Infra-Red and thus ground temperature, will slightly decrease the energy of the Ultra Violet radiation from the Sun.

What's the truth?

[It is possible that a rise in ground temperature might cause more sunny days - and this would certainly help the prospective wine growers of Yorkshire, but equally it might do the opposite. Details of future climate, rainfall, sunshine and cloud cover in a specific place are way beyond the abilities of our computer models.]

posted by grahamwell to science & nature (13 comments total)

It's already happening. There's a vineyard near Castleford - Leventhorpe, the most northerly commercial vineyard. You can see the vines on google maps. I've been for a tour, the whites aren't bad. Considering that it's officially in Leeds.
posted by handee at 12:52 PM on September 22, 2006

If I may be forgiven a bit of British Columbian chauvinism, our wines are already pretty good (though I'm not sure how many of them come from north of the fiftieth parallel.
posted by timeistight at 1:24 PM on September 22, 2006

Not to mention Ontario wines, but again Niagara is pretty far south
posted by TheWhiteSkull at 1:31 PM on September 22, 2006

Not for the first time:

...the Earth has been much warmer than it is presently (during the "medieval warm period" when Greenland was colonized and wine grapes grown in England).

I've seen other references to this period, I think ~500 years ago.
posted by trinity8-director at 1:33 PM on September 22, 2006

The medieval warm period was about a thousand years ago, and it ended with the "little ice age".
posted by Steven C. Den Beste at 1:41 PM on September 22, 2006

Canada already grows a lot of wine. I mean, we're not France, sure, but it's not so bad.

Also, I have no idea why you think UV rays lead to sugar production. I'm no biologist, but I don't think that has anything to do with it.
posted by GuyZero at 2:04 PM on September 22, 2006

Yeah, we do grow a lot of wine already, but grahamwell did mention a "robust Canadian Cabernet."

We do pretty well with Pinots, Merlots, and other grapes that don't mind a cooler climate and shorter growing seasons, but have you tried a Cdn Cab you'd consider robust (or drinkable, for that matter)?
posted by converge at 2:14 PM on September 22, 2006

Realclimate is rather dismissive of the Medieval Warm Period (but their key reference is broken). If it were real however it surely was not caused by the same factors as credited with warming today (our CO2 emissions), so a brighter sun and more sunspots is a possible cause and that certainly would allow a spurt of growth in Northern vines.

I understand that Wine is made in Alaska (I don't know how). I have no doubt that under special conditions you can grow good grapes very far North (under glass for example) or on particularly favoured hillsides (there's one in the Wye valley in Wales, a steep South facing slope which made wine for the recent G8 meeting). It's nice to know but it's not what I was after.

My mention of Ultra Violet may be a mistake. I did understand that the very energetic UV was important in the making of sugar but I can't find the source for that. I'm perhaps on firmer ground considering the reaction as simple photosynthesis, presumably through chlorophyll, and that seems to be driven by visible light.

The same consideration applies however. The sunlight won't get any brighter (at least not in the visible spectrum). The air and ground will get warmer - will that alone make better wine?
posted by grahamwell at 2:17 PM on September 22, 2006

England already produces great, if lesser known, vintages. They account for one per cent of all the wine sold in England, but they are generally quite good. You won't, however, find them at Tesco's.
posted by parmanparman at 2:20 PM on September 22, 2006

It's not quite as simple as "grape ranges move toward the poles," of course. A recent article in the Proceedings of the National Academy of Sciences gets into some pretty good detail, and though they only address the US wine industry, I think a number of their points (eg, increased days of extreme heat) are broadly applicable.

"Three central climatic conditions are required: (i) adequate heat accumulation; (ii) low risk of severe frost damage; and (iii) the absence of extreme heat. Although wine production is possible in an extensive climatic range, the highest-quality wines require a delicate balance among these three conditions. ... While increases in heat accumulation will shift wine production to warmer climate varieties and/or lower-quality wines, and frost constraints will be reduced, increases in the frequency of extreme hot days (>35°C) in the growing season are projected to eliminate winegrape production in many areas of the United States."
posted by nickmark at 2:36 PM on September 22, 2006

Unfortunately it's not the case that every place will just get warmer. For instance, a potential consequence of global warming is that the gulfstream, which brings warm air from equatorial regions to places like the will basically disappear. As a result, winters in places like the British Isles will become more severe, rather than warmer, per se. That's why people call it "climate change" instead of global warming.
posted by drmarcj at 7:20 PM on September 22, 2006

Looks like I'm just wrong on my cranky belief that it's all in the sunlight. If anyone's still interested in the subject, The BBC has comprehensive coverage of exactly this subject. I hadn't realised how important a factor frost is in the life of the young grapes (seeing frozen vineyards in Bulgaria in the depths of a four-month winter led me to assume that vines were basically resistant). Viniculture is a complex equation and many factors come into play.

drmarcj: indeed, we keep being told that - but this is a fascinating paper which makes a strong case that it is a myth. The Gulf Stream, it turns out, has less of an impact on winter temperatures in London than simple geography (yes, really).

That dream of a vineyard in the Brecon Beacons seems quite achievable.
posted by grahamwell at 4:44 AM on September 23, 2006

The dropoff in English vine cultilvation after the Black Death wasn't due to climate, but to labour - they didn't have enough people. Ladurie's book, Times of Feast, Times of Famine, covers the basic issues in the history of climate in Europe c1000-2000.

Also, Global warming means an average overall global increase in temperature. It could lead to colder temperatures in some places, or droughts, or massive climate change.
posted by jb at 7:46 AM on September 23, 2006