A FEASIBILITY study for the first large-scale copper and gold mine in Papua New Guinea's environmentally-sensitive Sepik River catchment suggests it will be even bigger than expected.

The Sepik is one of the largest wild river systems left in the Asia Pacific.

The mine owners said they would be using proven best-practice waste and pollution controls but environmentalists said the risk to the pristine Sepik and Frieda Rivers was huge.

The Frieda River Copper and Gold Project is controlled by an 80:20 joint venture between Chinese-owned company PanAust and Australian Stock Exchange-listed junior Highlands Pacific.

"It is important to understand what we have at Frieda River. What we are sitting on is one of the 10 largest undeveloped copper deposits in the world," PanAust managing director, Fred Hess said.

A PanAust announcement said its recently-completed feasibility study outlines a larger scale development than that proposed by previous owner Xstata.

That has scientists and environmentalists worried.

The Frieda River runs for 100kms from the mine site in the steep, forested highlands before it joins the Sepik which flows another 600kms through a wetland-dotted plain before reaching PNG's northern coast.

"From a biological perspective I can hardly think of a worse place for a copper mine," said mammologist Professor Tim Flannery, who made his name in Papua New Guinea identifying 16 mammal species previously unknown to science.

"I spent a decade in that general region doing a faunal survey and was able to show that the mammal faunas in that area were the richest in all of Australasia," he said.

The feasibility study said the project would build an innovative integrated waste management facility that would see both tailings and waste rock stored underwater.

Monash University environmental engineering senior lecturer Dr Gavin Mudd said integrated management makes sense in that environment but the risks are big.

"The total size of the resource is reported to be about 2.7 billion tonnes. That is just the ore they dig up that has got the copper and gold in it but ... there would probably be several billions of tonnes more of waste rock added to that," Dr Mudd said. - ABC

Islands growing, not sinking

Climate scientists have expressed surprise at findings that many low-lying Pacific islands are growing, not sinking.

Islands in Tuvalu, Kiribati and the Federated States of Micronesia are among those which have grown, largely due to coral debris, land reclamation and sediment.

The findings, published in the journal Global and Planetary Change, were gathered by comparing changes to 27 Pacific islands over the last 20 to 60 years using historical aerial photos and satellite images.

Auckland University's Associate Professor Paul Kench says the results challenge the view that Pacific islands are sinking due to rising sea levels associated with climate change.

"Eighty per cent of the islands we've looked at have either remained about the same or, in fact, gotten larger.

"Some of those islands have gotten dramatically larger, by 20 per cent or 30 per cent. We've now got evidence the physical foundations of these islands will still be there in 100 years."

Kench says the growth of the islands can keep pace with rising sea levels.

"The reason for this is these islands are so low-lying that in extreme events waves crash straight over the top of them," he says.

"In doing that they transport sediment from the beach or adjacent reef platform and they throw it onto the top of the island."

- ABC