A deep-sea oil spill could devastate some of New Zealand's favourite beaches, with the effects stretching as far as the International Date Line, new modelling from Greenpeace suggests.
Texan oil giant Anadarko begins exploratory drilling in the Taranaki and Canterbury basins this summer.
Greenpeace NZ asked scientists to make detailed estimates of how far an oil slick could stretch based on wind, tide and sea currents.
The results, which have been greeted with cynicism by the Government and exploration industry, suggest a blowout off the North Island west coast may reach as far as Northland, coating some of Auckland's west coast beaches.
A spill in the Canterbury Basin would drift out to sea and could reach as far as the International Date Line, almost 3000km away.
A lack of New Zealand-based equipment means it could take about 76 days to stem the flow.
Dumpark ocean modeller Laurent Lebreton said his team predicted the trajectory of 1000 oil-spill scenarios at the two sites.
"In the North Island scenario, a deep-sea blowout will probably have dramatic consequences for the entire western coastline and harbours from Taranaki's Cape Egmont to Opononi in Northland - including Auckland's west coast beaches," he said.
A catastrophic blowout could also spread across the Chatham Rise, which is a lucrative fishing ground, to the Chatham Islands.
A slick emanating from the Taranaki Basin could devastate internationally renowned surf breaks near Raglan and at Piha, and recreational fishing and sailing grounds of Manukau Harbour, the study said.
An east coast spill would threaten colonies of yellow-eyed and little blue penguins off Oamaru, Hector's dolphins which shelter in Banks Peninsula bays, and an albatross colony at Taiaroa Head, near Dunedin. Wildlife tourism is worth about $100 million to Dunedin's economy.
Greenpeace campaigner Steve Abel said the Government understated the risks of deep-sea drilling. The lobby group argues that exploration is the riskiest phase, as proved by the 2010 Deepwater Horizon disaster in the Gulf of Mexico.
University of Otago oceanographer Dr Ross Vennell said the report's scenarios were "conservative" and it took 152 days to drill a relief well in the gulf.
However, Auckland University head of department of engineering science Rosalind Archer questioned the estimated volume, which was as much as 40,000 barrels per day. "My assessment is that this report is likely to overstate the impact of a possible blowout in New Zealand waters," she said.
University of Waikato's Dr Willem de Lang said the study used industry-standard modelling but was limited by a lack of New Zealand-specific data.
Energy Minister Simon Bridges said the offshore petroleum industry had operated with a strong safety record since the late 1960s, with over 200 offshore wells sunk.
"The Government has taken a number of steps to strengthen regulatory processes and extend environmental protection measures to ensure they're on a par with the highest international standards," he said. "These steps make an oil spill exceptionally unlikely."
Petroleum Exploration & Production Association NZ chief executive David Robinson said the report assumed that a spill would take place, and that black oil would flow at a phenomenal rate.
"I think it is science fiction. It is no secret that Greenpeace are not fans of the oil industry."
- Fairfax Media
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