The routes could also bypass the Russian-controlled Northern Sea Route, say Brown University researchers said.

Climate models show that parts of the Arctic that were once covered in ice year-round are warming so quickly that they will be reliably ice-free for months on end in as little as two decades.

Projections show that by 2065, the Arctic’s navigability will increase so greatly that it could yield new trade routes in international waters – not only reducing the shipping industry’s carbon footprint but also weakening Russia’s control over trade in the Arctic.

“There’s no scenario in which melting ice in the Arctic is good news,” said Amanda Lynch, the study’s lead author. “But the unfortunate reality is that the ice is already retreating, these routes are opening up, and we need to start thinking critically about the legal, environmental and geopolitical implications.”

The researchers modelled four navigation scenarios based on four likely outcomes...