Getting warmer, going greener 30 June 2008

Martin Moore worries about global warming, and reports on better water management

Will next year still be the same?
Winter settled in as it always does in June with cold, misty days so typical of the Cape and (mostly) gentle rain. The sap has drained down into the roots, and outside my window the gnarled brown stumps of leafless vines on the slope opposite stand rather forlornly in their neat rows between the green cover crop. As they do every year. But somehow one looks at the scene with different eyes now. It is as if some of the innocence of the past is gone, that somewhat naïve acceptance that next year will be the same as this year which was the same as last year. One is increasingly becoming aware of the fragility of the world we're in, of the fact that, imperceptibly, things are changing, a mindset brought about by the dire warnings from scientists and researchers of the effects of climate change and the urgency with which we need to meet what must be the greatest challenge to face humankind.

At the same time one is somewhat paralysed by the knowledge that nothing we do can prevent global warming. The damage has been done and will continue to be done as countries burn fossil fuels and pollute the earth and the atmosphere to sustain their economies. As the French climate change specialist Bernard Seguin recently said: "If we emit less, there will be more warming; if we emit more, there will be more warming." All we can do, is to try and treat the world around us with all the consideration we can and in the process prepare ourselves for what seems inevitable.

The effects on our vineyards
But to be able to do that we need to understand what the effects of global warming will be on our vineyards. We all know the weather will get warmer, but by how much? We have only projections to go by. On the Internet I came across the research done by Dr Gregory Jones and his colleagues at the Southern Oregon University. They analysed climate data for the past 50 years, examining 27 of the world's high-quality wine regions and found that temperatures during the growing season had risen by an average of 2,0°C during that period.

For me the most interesting part of the study are the predictions for the next 50 years. To do so, Jones and his colleagues used a model used previously to predict changes in agricultural conditions. The results suggest that the 27 wine regions analysed can expect an average growing season temperature increase of 2,04°C by 2049. Of these regions, the largest predicted change was for southern Portugal (2,85°C) and the lowest for South Africa (0,88°C).

What do these climate changes imply? Not only will the annual rainfall in certain areas decline, but weather patterns will become increasingly erratic, with violent, and sometimes unseasonal, downpours causing flooding instead of the gentle rain that nourishes the soil and builds up the water table. Water will become an even more precious resource and preference will have to be given to cultivars needing less. At the same time we can expect that, with increasingly milder winters, dormancy will start earlier and so will budburst. We also know that as carbon dioxide levels in the atmosphere increase so does photosynthesis so that the ripening rate of the grapes will quicken. All of this is bound to affect the quality of the end product, and there will have to be much more intervention in the cellar to produce wine of acceptable quality.

But there's more...
That is not all. Scientists predict the warming climates will encourage new pests and diseases with notably insects moving into new habitats. This seems to be happening already, with the so-called Asian Lady Beetle, a bug that taints wine with methoxypyrazines, suddenly appearing in the US as well as Italy, Belgium and the UK, and, according to reports, "breeding like crazy". This phenomenon could present a challenge to especially organic and biodynamic growers, although it is also claimed their vines will be better adapted to the new conditions.

We are extremely fortunate that the cellar and its supplier vineyards all lie within the coolest winegrowing area bar one in the Cape Winelands. However, that is no reason for complacency. We will have to develop higher-lying areas for new vineyards without losing our indigenous vegetation. We will have to experiment with cultivars that can withstand increased temperature levels. And we will have to adapt our canopy management programmes to even more carefully control ambient temperatures around grape bunches while on the vine. And we will have to protect our resources at all costs.

Trying to do things better
I said at the start with all this in mind, how one starts responding so differently to the world, how one becomes motivated to try and do things better even while knowing that, in the greater scheme of things, what one does will make very difference to the end result. One is also encouraged by the fact that we are not alone, that there are hundreds of like-minded people in the South African wine industry - grape producers, viticulturists, winemakers, researchers, scientists - all to a greater or lesser degree working towards the same common goal of preserving our environment.

Several years ago, Durbanville Hills received ISO 14000 accreditation, a programme aimed primarily at operating the cellar in an environmentally sensitive manner. Through careful management we have cut down on the volume of water used during the vintage by about a third, and of that not a drop gets lost these days. It is all pumped to a large storage dam on the hill above the cellar where it is aerated and the pH restored. From there it flows down to one of our members in the valley who uses it for irrigation.

And, rather than having husks and stalks carted away as happened in the past, we are implementing a programme of turning these into compost to be used by our supplier members in their vineyards instead of chemical fertilisers. You can get quite far with the compost from about 2 000 tons of such organic waste, let me tell you.

And here I have become so engrossed in global warming and how it will affect us that I have again run out of space and will have to return to the question of our so-called green, burnt reds in the next newsletter.

• This contribution is  taken, with permision, from the Durbanville Hills June newsletter. It appears in full on the Durbanville Hills website.