Climate change and nuclear weapons, the two great security threats of the 21st century, are uniquely influential in the Arctic. Although the current risk of conflict is low, the global future is potentially turbulent. There is a ‘new’ Arctic because of meltdown induced by climate change. Some see great economic opportunities; others see ecological and human security threats. Governance requires new national and multinational agreements; now is the time to gain acceptance for a future nuclear-weapon-free Arctic.