Significant shift in New Zealand climate

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A significant shift in the New Zealand climate has occurred during the past 20 years.

Detailed research of climate records by scientists of the National Institute for Water and Atmospheric Research (NIWA) revealed that since 1977:

  • The north and east of the North Island has become 10 percent drier and five percent sunnier with more droughts
  • The west and south of the South Island has become 10 percent wetter and five percent cloudier with more damaging floods
  • Fewer frosts are occurring nation-wide
  • The retreat of the west coast glaciers has halted but eastern glaciers continue to shrink
  • Night temperatures continue to rise.

The research was carried out by climate scientists Dr Jim Salinger and Dr Brett Mullan. They analysed climate records and main weather features in the New Zealand and south Pacific regions between 1930 and 1997.

They say that the changes in average temperature and rainfall totals have impacted dramatically on the number of climate extremes, such as frosts, floods and droughts.

"The changes have resulted from the strengthening of the anticyclonic belt which brings fair weather to northern New Zealand. It has squeezed stronger westerly winds over southern and central New Zealand."

"This climate shift has prevailed for two decades with variations around this new average since the mid-seventies."

The Chief Executive of NIWA and President of the Crown Research Institutes Association (ACRI), Mr Paul Hargreaves, said the climate shift had significant implications for pastoral industries, forest, crop and fruit growers, water supply authorities and hydroelectricity generators as well as property owners.

"We have already seen dramatic changes in our land and environment. Droughts have become more frequent in the north and east of the North Island. Flooding is more frequent on the west coast of the South Island."

"The higher rainfall is causing the Franz Josef and Fox Glaciers to push out. Fewer frosts have allowed the spread south of sub-tropical grasses, insect pests and diseases."

"These New Zealand changes are linked to larger scale climate changes in the south Pacific and other world-wide variations. Since 1977 there has been more than a 150 km movement east of a vast belt of storms and winds in the south Pacific between Fiji, Samoa and Tonga, known as the South Pacific Convergence Zone. El Nino events have become more frequent. These developments have resulted in the Northern Cook Islands, Tokelaus and parts of French Polynesia becoming substantially wetter. At the same time Fiji, Tonga, Vanuatu and New Caledonia have become drier."

"It is apparent that 1977 was a key year in which significant changes in climate occurred in the Pacific Basin. An abrupt shift in the climate of North America also occurred. Global average temperatures, which showed little change from 1940 to 1977, then warmed 0.3°C by 1997."

"NIWA is undertaking further research to understand these changes and to predict whether they will continue by continuing analysis of South Pacific climate records and by computer modelling of global climate. It is also working on seasonal predictions of climate."

"The challenge now facing CRIs is to advise the Government and stake holders on the impact climate variations will have on specific sectors."

"They will he expected to come forward with solutions that will minimise adverse environmental, economic and social consequences and to identify new opportunities for national development across a broad spectrum of agriculture and industry."

"The situation re-emphasises the value of a vigorous and soundly funded research sector capable of responding positively to fundamental changes in the environment," Mr Hargreaves said.

"The outcome of their research will be of considerable importance to a wide range of political, agricultural and industrial interests."

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Principal Scientist - Climate
 

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Archived on 15 April 2019