Indigenous Sami herders and fishermen argue the plan, which was approved by Oslo on Thursday, will add to the existing problems of climate change, oil spills and poaching affecting their homes and livelihoods.
Up to 66 million tons of copper ore are believed to be in ground in Kvalsund in Finnmark – Europe’s northernmost region deep inside the Arctic Circle.
Environmentalists fear it will lead to mining and drilling projects in other fragile ecosystems in the Arctic, which has become the latest frontier in the quest for rapidly depleting mineral and fossil fuel reserves.
Melting sea ice has allowed heavily polluting ships to enter pristine habitats and nations are eyeing up its precious natural resources.
The Arctic is warming at twice the rate of the rest of the planet and current trends suggest the polar region will be ice-free during summer as soon as the 2050s.
This is opening up commercial opportunities both for resource extraction and cruise vessels.
Norwegian mining company Nussir, which owns all of the mining rights, said it would make use of the area’s deep-sea, ice-free port, a major highway and a “developing industrial zone” which was already in place.
The company said it was committed to “minimal intrusion in our host community’s way of life”.
Torbjoern Roe Isaksen, Norway’s industry minister, also insisted the project would “contribute positively to the local community, with new jobs and skills”.
But reindeer herder Nils Mathis Sara said the plan was evidence that Oslo was not taking their concerns seriously.
“I am shocked by the government’s decision. I had hoped that the Norwegian government would have heard our arguments,” he told the Reuters news agency.
Environmental groups fear mining for copper would destroy the land reindeer depend on in the summer months.
And a plan to dump mining waste into Repparfjord coastline threatens spawning ground for Atlantic salmon.
“This is one of the most environmentally damaging industrial projects in Norwegian history,” said Silje Ask Lundberg, leader of Friends of the Earth Norway.
Activists said two million tonnes of heavy metal waste will be dumped every year – the equivalent of 17 lorry loads every hour – into a fjord given special protection to conserve salmon.
Earlier mine waste dumping in the same fjord, at a lower level than planned in the project approved today, led to a large drop in the salmon populations that took 13 years to recover. Cod populations have still not returned to their former spawning grounds
“This decision shows conclusively that the government does not take the fight to conserve ocean life seriously, and would rather prioritise short-term profit over conservation and sustainability,” Ms Lundberg added.
Norway is the only country in Europe – and one of only five in the world – that allows mining companies to dump solid mine waste directly into the sea.
Environmental charity Earthworks said dumping mine waste in the Repparfjord in the 1970s “nearly wiped out” the area’s fishing industry.
Critics are considering whether to take legal action, potentially delaying the project, which had been waiting on a government licence since it was given the green light by local officials in 2012.
Around 2,500 people have also signed up for civil disobedience against the project.
The British government has promoted mining across the Arctic, writing in 2014 that Norway’s “considerable mineral resources” presented “excellent opportunities for growth”.
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