What exactly is a 'cool climate wine'

This may sound like a very simple question, but the term 'cool climate' has been overly used in Australia to the point where no one actually knows what constitutes a 'cool climate wine'. In this article we are going to (attempt to) arrive at a conclusion on what's 'cool' and what's not.

For the most logical answer, we went straight to the top - to Australia's peak government wine body, the Australian Wine and Brandy Corporation. The AWBC (or these days, Wine Australia) define Australian wine areas (and the subsequent climate classifications) in terms of Geographical Indications (GIs). GIs are the official Australian description for a wine zone, region or sub region - so you can have a Limestone Coast GI (which is a zone and a conglomerate of regions including Padthaway, Coonawarra etc..) or a Frankland River GI (which is a sub region and is small & unique). (The AWBCs list of GIs is here)

As for delineating the cool from the rest, the AWBC then goes on to defines GIs as either cool climate or warm climate. There are only a handful of warm climate GIs - including the Riverland, Murray–Darling, Perricoota, Riverina and Swan Hill - all areas based around our warm, inland, irrigation fed wine regions. The problem then is that any wine producing area outside of these areas can, according to our peak Government body, call themselves 'cool climate'.

As anyone who has spent some time in the Hunter or Swan Valley in January can tell you, the AWBC definition is a long way from accurate & out of step with global expectations on what makes a cool climate wine.

For a better interpretation, we went to the National Cool Climate Wine Show (NCCWS). Held in Bathurst every year, this show is purely devoted to cool climate wines and thus has a clear definition of what constitutes a cool climate wine.

In the NCCWS regulations the definition of 'cool climate' is:

a) Heat Degree days 1600 or less
b) Cool nights in growing season
c) Four distinct seasons
d) Large variation in diurnal temperatures
e) Cool Autumns

Much of this is also quite broad in its definition (How cold is a 'cool night' or a cool autumn - it can get pretty cold in the Hunter in May, yet stifling hot in March). The 'Heat Degree Days' measurement however is a very particular measure of vineyard warmth that is used by grape growers around the world to compare climates.

Heat Degree Days are measured by taking the average temperature per day (°C) minus 10, multiplied by the number of days in the 7 month growing season (Oct to April in the Southern Hemisphere). The base is 10 as vines do not function below 10°C.

To get some perspective, the table below (from Geoff Weaver) shows Heat Degree Days (HDD) of some global wine regions:

Region	HDD
Champagne, France	1131
Burgundy, France	1264
Lenswood, Adelaide Hills, SA	1278
Bordeaux, France	1420
Coonawarra, SA	1437
Napa Valley, California	1499
Barossa Valley, SA	1587
Mclaren Vale, SA	1765
Hunter Valley, NSW	2075
Riverina, NSW	2201

As you can see, the Barossa Valley would scrape in, but with its quite low diurnal temps and warm autumns would be essentially ineligible.

So going by these guidelines and using the HDD measurements, we start to get a clearer picture of where a cool climate wine comes from. I've set the table up below to show a few examples of what are true cool climate GIs, what could be more accurately described as 'moderate' climate GIs and what are warm climate GIs (based upon HDD and climate figures).

Cool	Moderate	Warm
Tasmania	Barossa Valley, SA	Riverland, SA
Eden Valley, SA	Langhorne Creek, SA	Riverina, NSW
Coonawarra, SA	Clare Valley, SA	Hunter Valley, NSW
Orange, NSW	Mudgee, NSW	Swan Valley, WA
Yarra Valley, Vic	Mclaren Vale, SA	Murray Darling, Vic
Great Southern, WA	Rutherglen, Vic	Adelaide Plains, SA
Margaret River, WA	Granite Belt, QLD	Swan Hill, Vic
Canberra District	Goulburn Valley, Vic	Peel, WA
Mornington Peninsula, Vic	Hilltops, NSW	Perricoota, NSW
Adelaide Hills, SA	Bendigo, Vic	Cowra. NSW

This list is by no means definitive - Mclaren Vale, for example could be warm climate but it abuts the Adelaide Hills & thus has considerable variation within the GI. Similarly, Cowra is very warm, with a high HDD, yet has quite cool nights.

So beyond the scope of where cool climate wines come from, what do they taste like?

Cool climate grapes will be subject to less heat during the growing season, with the grapes taking longer to ripen and often achieving significantly lower sugar levels than their warm counterparts. This translates into finished wines that may have lower alcohol levels & higher levels of natural acidity.

Cool climate wines are often thus 'drier' and more 'savoury & elegant' in style. The flip side of course is that the soft, opulent generosity that characterises many Australian wine styles is often absent in cool climate wines, with cool climate wines regularly emphasising wine structure over obvious fruit (which not everyone is attracted to).

The problem also with cool climate vineyards is that they normally yield less than warm ones; are more expensive to maintain and prone to the vagaries of the very cool climate that imbues them with character - Frosts are the enemy of cool climate vineyards.
Following on from this, many varieties need the warmer climates to achieve full ripeness - In the Mornington Peninsula, Cabernet struggles to ripen & even Shiraz can have an element of greenness to it & Tasmania sticks to early ripening Pinot Noir as most other red grapes are challenged to even ripen in all but the warmest vintages.

What ultimately defines cool climate wines however is acidity. Acidity = refreshment. Acidity keeps wines tight and crisp even after decades in the bottle. In warm climate wines, acid is added to the final product to keep it stable and, well, fresh! Acidity is the lovely dryness that comes from cool climate Sauvignon Blanc. Acidity is what makes Orange Chardonnay's that much more taut & pristine.

In short acidity is a crucial ingredient of wine, and the more natural grape acidity (when in balance) the more vibrant the wine can often appear - particularly in white wines. Winemakers love natural acidity - it makes their job easier. Thus winemakers love cool climate wines. Thus we have a preference of quality focused winemakers towards cooler climate wines. Thus we have Australia's finest winemakers making wine in cool climate regions (or 'moderate' regions at the most. There are, naturally, many exceptions).

Ultimately we can conclude that cool climate wines = Premium wines.
Or do they?....

Andrew Graham