Seas may rise even higher

Scientists are predicting seas will rise higher than the levels the Environment Ministry advises local councils to plan for.

Delegates in Copenhagen for the United Nations climate change conference next month are to be told of the new predictions, which draw on new satellite images of Greenland and Antarctica.

The Intergovernmental Panel on Climate Change has predicted a sea level rise of up to 59 centimetres by the end of the century. However, the director of the Antarctic Research Centre, Tim Naish, said the international community now believed sea levels could rise by 1.9 metres.

Environment Minister Nick Smith said the Government was working on establishing a national environmental standard on planning for sea levels, which he hoped would be in place next year.

He hoped to put the standard out for consultation next year, but said it was likely that councils would still be required to plan for a rise of 59cm.

"The Government is not going to consider adjusting its policy every week," Dr Smith said.

In its advice to councils, the ministry says that as sea levels rise, more high tides will flood coastal land. Waves will have more chance of attacking backshores and foredunes, and erosion of beaches will worsen. More estuaries and harbours will flood, cliffs will retreat, and existing coastal defences could be damaged. That could leave the land and buildings behind existing sea walls without protection.

Ministry senior analyst Warren Gray said the current advice to councils was to plan for a sea level rise of 50cm, and consider what a rise of 80cm could mean. He said some were planning for sea level rises of up to 1.5 metres.

"We want people to be safe, but not building defences that are not necessary," he said.

A new IPCC report is not expected to be published until 2013, but Dr Gray said that if an interim report was completed, the ministry's advice could be reviewed.

The new data was presented at a media briefing held by the Science Media Centre and NZ Climate Change Centre in Wellington yesterday.

Dr Naish said he believed that the new figures would impress the urgency of the problem upon policy makers.

They were particularly relevant for New Zealand, where such a large portion of the population lived on the coastline, he said.