Capt. Pal Bratbak has patrolled the Barents Sea for decades. His Norwegian coast guard search and rescue cutter mostly chases after distress calls from fishermen. The fishermen are chasing the cod — and the cod sometimes lead them astray.

"The codfish, they don't see the border, so we help every boat in our area," he says, and that means as many Russian boats as Norwegian. A treaty allows both nations to catch a quota, and that management of the Barents Sea Arctic cod fleet is considered a success worldwide, both economically and environmentally.

"That's important for Norway and the European Union and NATO and the whole world. And it's important for the Russians," he says.

Cooperation like that has been a given on the Russian-Norwegian frontier for decades, if not centuries. The Norwegians call it "high north, low tension."

Since Russia's invasion of Ukraine, though, that tension isn't so low, and Bratbak is worried. The coast guard also enforces the fishing laws in the Barents Sea.

Years ago, in a rare case, a Russian trawler fled from a coast guard ship, into Russian waters — with Norwegian inspectors on board. Back then, Russian authorities promptly arrested the captain and returned the inspectors. Bratbak hopes the same cooperation would happen today, but his confidence is a bit shaken by recent events.

"In these days, Russia can use other methods to negotiate. Like in the Ukraine conflict, they are willing to use power (more) than talking," he says.

Critical climate work is on hold

As a founding member of NATO, Norway's government has joined the rest of Europe in isolating Russia. But as a country bordering Russia, it's feeling the effects more immediately than some others — in everything from Arctic climate action and nuclear waste control to cross-border trade and regional sports leagues.

The protection of the pristine waters of the Arctic, as well as that cod fleet Capt. Bratbak mentioned, falls under an international group called the Arctic Council. The rotating chair of that group is currently Russia, and as such the council has suspended all activities, including crucial research on climate change.

"It's not something you can point out that failed today, but it's ongoing," says Kim Holmen with the Norwegian Polar Institute in Tromso, where the Arctic Council would normally be coordinating research.

Russia has about half of the world's Arctic landmass, including permafrost that, if it melts, could release megatons of trapped carbon and greenhouse gases.

Scientists like Holmen count on collaboration with their Russian colleagues.

"We have common publications. We have collected data together. We've been on each other's cruises. I've been to people's homes in Saint Petersburg, good friends," he says.

Holmen isn't in contact with those friends right now. He's been working on the Arctic for more than 30 years, and he says the lesson from back in the Soviet days is that communication will only get them into trouble, which would delay getting back to work.

"Polar scientists are used to the cold," says Holmen. "We hope and wish to pick up when it thaws."

"We are seeing the Iron Curtain come back"

For residents of the border city of Kirkenes, their world changed overnight.

Guro Brandshaug is CEO of the Kirkenes Conference, an annual businesses summit between Russia and Norway. This was the 14th year the event was held, and, on a weeknight in February, it all started out relatively normally.

"On Wednesday the 23rd I welcomed our foreign minister and the Russian ambassador," says Brandshaug.

With Russian troops massed on the Ukrainian border, she says, it was tense. But Kirkenes is a city built on friendly relations with Russia, and Brandshaug says no one she knew thought Russian President Vladimir Putin would really invade.

"And then we woke up on the morning on the 24th," she says. "The Russians had started bombing Ukraine. It was a huge shock. People were actually crying."

A nuclear waste dump poses a constant threat

"Everything that has been built up over the last 30 years, was just washed out in a few days. We are seeing the Iron Curtain coming back," says Thomas Nilsen with the Barents Observer newspaper in Kirkenes.

The new Iron Curtain severed personal ties, economic links and even scuttled issues of mutual survival, Nilsen says. For years, Norway had been helping Russia safely dispose of spent fuel rods from its aging nuclear submarines, which were stationed in the Arctic.

At a park station in Svanvik, scientist Bredo Moller collects air samples for the Norwegian radiation safety authority.

"We are some, some kind of a nuclear watchdog on the border to Russia," he says. "That's more or less why we're here — to monitor what's on the other side of the border, just a few kilometers from here."

He's referring to one of the world's biggest nuclear waste dumps, across the border, where tons of waste from Russian power plants and aging submarines pose a constant threat, either as a contaminant to the Arctic sea life or as material in a terrorist dirty bomb.

Moller says that just last November, Norway marked 25 years of cooperation on nuclear cleanup, and he went to Murmansk in Russia for a celebration with his colleagues.

"I have many friends in Murmansk, shaking their heads like me, waiting for this to end," he says.

Moller is counting on those colleagues to keep up the work of saving the Arctic from nuclear contamination. And he's certain his friends oppose the war in Ukraine just as he does — they just can't speak right now. But it's chilling that many local officials across the border, as well as 700 rectors and university presidents in Russia, have issued strong statements supporting Putin. And that makes Moller worry that even this vital work might not resume soon.

"It will take many, many years I'm afraid, to get back to that trust that we have gained through these 25 years of cooperation. So, yeah, it is frightening times," he says.