Climate Change in the Moorabool Valley

We’ve done the digging on climate change

If the media coverage in the last few weeks is anything to go by, you could be forgiven for thinking that it’s only the latte-sipping, avocado munching, city dwellers that are crying foul about climate change. Though dig a little deeper and you’ll also find it’s the chardonnay and pinot drinkers who are also feeling the effects.

After doing a little digging, here’s some insights on the subject that is currently dividing the nation.

The Change in temperature

The above chart maps the temperature over the last 27 years here in the Moorabool Valley, with three simple lines showing the average maximum and minimum temperature, with the average in the middle. Proof (if you need it) that when it comes to temperature, things are inarguably on the up.

“But hey,” you might say, “that’s only over the past 27 years, perhaps the changing climate is part of a 50 or 100-year cycle of temperature fluctuations.”  Ok sure, that’s one argument, but I’m going to leave that to the climate experts to debate. My focus is on how the current climate affects what we do as winemakers and how these rising temperatures are going to impact the taste and quality of our wines.

In the early years of winemaking in Geelong (i.e. the 1960-70s) honestly, there were years when achieving full ripeness was hard going, and late ripening varieties like cabernet and shiraz struggled to get to the ripeness level required to produce a decent drop.  The upside is, that’s why pinot noir and chardonnay became the go-to varieties to plant in the Geelong region. With their early ripening nature, growing in a cool climate, we had a better than even chance of making something delicious.

The change in harvest times

But what once was a harvest decision made in late March or April, is now increasingly a February decision for these early ripening varieties. In warm conditions, sugar accumulates quickly in the grape, as sugar ripeness is influenced largely by temperature. While the other important grape components that influence wine quality, namely tannin and flavour development, ripen at different rates because they are influenced by factors other than just temperature.  Generally, long slow ripening conditions lead to a more subtle, nuanced wine with brighter aroma, better acidity and pH. These wines will age nicely and take on a more complex flavour profile.

Does climate change affect the taste of wine?

However, we here at Austin’s aren’t giving up just yet on producing nuanced, silky pinot noir, even though the last couple of vintages have been the warmest on record.  We have tried to overcome what nature has thrown our way by judicious, strategic irrigation and also leaving our foliage largely untouched to provide more shade.

However, going forward, water could be the limiting factor, as our increasing water requirements are limited by what Mother Nature provides.  The graph below shows our rainfall pattern over the last 24 years and could seem to show that rainfall is only marginally influenced by global warming, though since 2013, the trend is beginning to look more ominous.

So far, the wines we have produced at Austin’s during the warm 2018/19 years, encouragingly still have all the lovely flavours that we like to see, though how persistent this is, remains to be seen.  We are definitely seeing a decline in natural acidity and rising pH in some varieties, particularly pinot and chardonnay, and there is still the issue of how they will look as aged wines in years to come.

 We are still trying to pick our best batches around the 12.5 to 13.0 Baume level and through our regulatory body, Wine Australia has given Aussie winemakers permission to add water to the wine to lessen the impact of high alcohol, due to increased sugar levels in grapes caused by climate change. This will ensure that our wines are structurally similar to what we want but certainly not an answer to how increasing temperatures will affect the flavour profile of our grapes.

Time will tell where the tipping point is for Geelong winemakers in producing delicate, nuanced complex wines or just overripe dry reds and whites. But the answer, my friends, could be blowing in the wind (turbines)….and solar panels.

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