Tuesday 22 September 2015

Faster than previously thought...climate change in New Zealand

Climate events put NZ coast at risk

An international study suggests New Zealand's coastlines could be harder hit by climate patterns than scientists previously thought

22 September, 2015

Waves crash over the breakwater at Port Taranaki.
Coastal impacts from La Niña could be worsened by rising ocean levels.  Photo: RNZ / Robin Martin

Researchers analysed data from 48 beaches bordering the Pacific Ocean from 1979 to 2012 to see whether patterns in coastal change were related to major climate cycles such as El Niño and its counterpart, La Niña.

La Niña is related to the cooling of surface ocean waters along the tropical west coast of South America. The El Niño weather pattern, expected to hit New Zealand this summer, is characterised by unusually warm ocean temperatures in the equatorial region of the Pacific Ocean.

The researchers from 13 institutions, including the University of Waikato, discovered that during periods of La Niña many stretches of New Zealand's coast had to cope with powerful waves and erosion.

Lead author Patrick Barnard from the US Geological Survey said New Zealand could have more coastal damage than in earlier years.

"More extreme La Niñas in the 21st century, as projected by recent global climate models, suggest New Zealand could experience more extreme coastal impacts during La Niña events than recently experienced, which would be even more amplified by global sea level rise."

He said this research would be helpful in future weather events.

"Understanding the effects of severe storms fueled by El Niño or La Niña helps coastal managers prepare communities for the expected erosion and flooding associated with this climate cycle."

The research group found that all the regions in the study were affected during either weather pattern.

When the west coast of the US mainland and Canada, Hawaii, and northern Japan felt the coastal impacts of El Niño, including bigger waves, higher water levels and erosion, the opposite region in the Southern Hemisphere of New Zealand and Australia experienced 'suppression,' such as smaller waves and less erosion, the study said.

The pattern then generally flipped; during La Niña, the Southern Hemisphere experienced more severe conditions.

Ocean erosion threatens the coastal route.Sea damage to a cliff in the South Island (file photo)
Photo: RNZ

Cold spring ahead as El Niño tightens grip

New Zealand is facing a cold spring and dry summer as strong El Niño weather patterns persist, according to the National Institute of Water and Atmospheric Research (NIWA).

3 September, 2015

Photo: 123RF

The institute's latest climate outlook said there were signs this year's event could be one of the four strongest ever recorded.

The report said the phenomenon, which increases the chance of drought in the east, heavy rainfall in the west and cooler weather, was extremely likely to continue into early 2016.

It said there was an increased risk of drought this summer in the north and east of the North Island, and the east of the South Island.

Cold weather and low rainfall are also expected for parts of the country during spring.

What's expected for spring:

  • The west and east of the South Island are most likely to experience colder-than-average temperatures. Cold snaps and frosts are expected in some parts of the country from time to time.

  • In the North Island and in the north of the South Island, average or below average temperatures across the season are about equally likely.

  • The north and east of the North Island - Northland, Auckland, Waikato, Bay of Plenty, Gisborne, Hawke's Bay and Wairarapa - are most likely to experience below normal rainfall.

  • River flows in the east of the South Island are most likely to remain low - but there are about equal chances of normal or below normal levels of rain.

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