Frequent droughts for farmers as climate change hits

The risk of severe droughts capable of crippling farmers and horticulturists could increase fourfold in eastern New Zealand over the next 75 years.

Some regions which are already drought-prone - such as Marlborough - could see what is today considered a one-in-20-year drought occurring every three to five years by the 2080s, says a National Institute of Water and Atmospheric Research report released by Cabinet minister Pete Hodgson, who chairs the Cabinet's climate change committee.

"Climate change poses a direct threat to New Zealand's environment, way of life and economy," he said yesterday.

The report said that drought usually had the largest impacts of any national or international calamity on New Zealand's economy.

"The drought of 1997-98 was bigger economically for New Zealand than the 'Asian [business] crisis'."

According to the NZ Institute of Economic Research, that drought cost $407 million or 0.4 per cent of gross domestic product.

The report set out a range of four scenarios, based on two computerised climate models, one at the CSIRO in Australia and one at the Hadley meteorological office in Britain.

It said that New Zealand agriculture's heavy reliance on rainfall meant that just 21 days without rain was often enough to trigger drought-like conditions.

The report said there were possible increases in drought risk in inland and northern parts of Otago, eastern Canterbury and Marlborough, Hawkes Bay, the Bay of Plenty, the Coromandel Peninsula, parts of Wairarapa and Northland.

In the two scenarios it considered in detail, severe droughts were likely to become between two and four times more common in these parts of the country.

Mr Hodgson said the areas at risk represented a large proportion of the nation's prime agricultural land for cropping, dairying, sheep farming, viticulture and market gardening.

"The results are alarming," he said.

He said the 1997-99 Canterbury drought directly cost farmers $230 million, and the Australian drought of 2002-03 slashed agricultural output across the Tasman by 30 per cent, costing Australia 70,000 jobs and a 1.6 per cent drop in GDP.

The report said farmers had adapted well in recent years to short droughts lasting about three months, but longer drought had more serious effects.

Mr Hodgson said farmers had learned from previous droughts how to harvest and store water, and breed more efficient and drought-resistant pastures.

But he said some of the coming climate change-induced droughts would be well outside what the nation was used to: "adapting farming and water management practices will only go some way to offset the increased risk".

What climate change could mean for NZ farmers:

* Severe droughts every three to five years in some areas.
* Farming would no longer be viable without irrigation.
* Main regions affected: inland and northern Otago, eastern Canterbury and Marlborough, Hawkes Bay, Bay of Plenty, Coromandel Peninsula, parts of Wairarapa, Northland.