Last week’s rain which varied from 12 – 30 mls in different parts of North Otago has lowered temperatures. So while noting the touch of frost on my morning walk I wondered if it would be all bad news if the globe is warming?
The EcoClimate report, Costs and Benefits of Climate Change and Adaption to climate change in New Zealand, which was released by MAF yesterday, says that farming may be better in some areas if the temperature rises a degree or two.
The full report is here and the authors stress it should be regarded as part of the risk assessment of what could happen to production not a firm prediction on what will happen.
The Herald says the impact of climate change wouldn’t be all bad, but the bad effects would be worse than in the past.
The expectation for North Otago is it will be warmer which could mean an earlier growing season. However, it might also be drier with a greater risk of droughts.
“For an average year in the future the predicted changes are small when averaged across the country,” said MAF’s director of national resources policy, Mike Jebsen.
“But different parts of the country are affected differently, with the west becoming wetter, the east drier and all of the country becoming warmer.”
The growing season will get longer, especially in Southland and the West Coast. But although production is expected to increase there, it will decrease in Northland and some east coast areas.
In an average year in the 2030s or 2080s the expected impact on national export revenue from dairying, compared with now, is expected to be minimal. For sheep and beef farming it would be between 4 and 9 per cent lower.
But in extreme years droughts are expected to be worse than those experienced in recent decades, like the 1977/78 and 1997/98 episodes, and national production from pastoral farming would be almost halved.
Econometric modelling by the Treasury a few years ago found drought to be the second most potent influence on the New Zealand economic cycle, after export prices.
We know all about that in North Otago which has been dogged by recurring droughts. The impact on individuals is as harrowing as ever, though the impact on the district is getting less as irrigation increases.
Droughts would become more frequent, said Niwa scientist David Wratt, and the work suggested the likelihood of the especially damaging case of a two-year drought might be higher.
“What is now a one-in-20-year drought might become a one-in-five-year one later in the century.”
The work takes no account of any increased risk of pests and diseases which might arise from higher average temperatures (about 2C over the rest of the century, twice the increase of the past 100 years), with fewer frosts and more hot days. Nor does it attempt to model how farmers would react to these climatic changes.
“It takes no account of adaptation, for example, water harvesting and storage or going to drought-resistant plants,” Jebsen said.
More precipitation on the Southern Alps might mean more water coming down the South Island rivers, increasing the potential for irrigation.
North Otago Irrigation Company (NOIC) is already working on the second stage of its scheme which has consents to water 20,000 hectares. The scheme has 100% reliability of supply because it takes water from the Waitaki River which is snow fed.