Opinion: Climate situation not without hope

Rising temperatures could have major impacts for industry in the Marlborough Sounds.

Rising temperatures could have major impacts for industry in the Marlborough Sounds.

OPINION: Earlier this month NIWA issued a report on the likely changes to the Wellington region's climate by the year 2090. Though Marlborough's weather is quite distinct from that of Wellington, one can safely say that, given their close proximity, a rise in Wellington's average temperature is likely to be matched by similar rises in Marlborough.

The main points in NIWA's report were that: the average annual number of 'hot' (over 25 degrees Celsius) days in the capital would increase from the present six, to 26. (In the Wairarapa, the jump would be from the current 24 hot days to 94!)

Though the average temperature has risen by 1C in the past hundred years, in the coming 70 years (the time between today's newborns and their pensions) the average temperature will increase by a further 3C, with autumns showing the highest increase. Spring rainfall will decrease, but be matched by an increase in winter rainfall and an increase in the number of extreme rainfall events.

Clearly, such an increase in the speed of change in the Marlborough climate is going to have a significant impact on its primary industry-based economy. We asked Gerald Hope, chief executive of the Marlborough Research Centre, what he thought would be the implications for Marlborough's agriculture, horticulture, viticulture, forestry and aqua-culture industries. How should they adapt to the changed conditions?

At the outset of the interview, Hope made clear that the views he expressed were his personal views and not necessarily those of the research centre. In his view, there was much that could be done to adapt to the changing conditions and that these adaptations "should have begun yesterday".

He believed that adaptation to a 3C rise in average temperature and seasonal adjustments in the rainfall pattern were well within the province's capacity. In his view, the most urgent need was for a rapid increase in Marlborough's already growing water storage capacity.

"… we would be negligent if we didn't store our water in the winter and harvest it in the summer: water storage is the key to productivity."

He suggested that while the increased sea temperatures and acidification were likely to adversely affect both mussel and salmon farmers, possibly forcing them to move further offshore or relocate into the more limited number of suitable sites further to the south, there were plenty of opportunities for new species to be introduced into Marlborough waters.

Though no-one had tried it yet, he was sure that the relatively warm and shallow water storage ponds would be developed and, as they are in Asia and as the economics started to make sense, adapted for intensive freshwater aquaculture.

Marlborough was lucky in that the high water-usage dairy industry was largely absent from the province. The viticulture that had replaced it, as a significant consumer of irrigation, was that much less thirsty and was not responsible for the excessive nitrogen inputs that were so damaging to waterways. Inevitably, over time, the flavours and the varieties of the grapes grown would change and those horticultural crops dependent on winter chill might become unviable and be replaced by other fruits.

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The most serious problem that lay ahead was the temperature rise opening up the province to new varieties of pest and diseases. In Hope's words "… the biggest threat to Marlborough is pest and diseases, because everything else is there. As long as we maintain soil quality and health and store and use water well, we will be in a good place."

The other problem he mentioned was that of wilding pines taking over vast tracts of the back-country.

After the interview, I did some research on wilding pines. To me, in the present crisis, any plants, including wilding pines, which sequester carbon, have to be viewed positively. In common with Hope, Landcare Research has a different view: "Because these trees grow in dense stands, and are not able to be managed as a plantation, they have no economic value. Instead, wildings can reduce the value of managed pasture, displace native biodiversity, reduce water availability, and alter the character of the landscape."

The optimistic message offered by Hope at our meeting, is of course dependent on the success of global efforts to mitigate climate change. We did not discuss the implications of what would happen should international attempts to check the rapid rise in temperatures prove inadequate.

If the first hundred years raise the temperature by 1C and the next seventy by 3C, how long will it be before the average temperature rises by a further 3C - and in what sort of ruin would that leave our province?



 - The Marlborough Express


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