I'm standing outside a Shell petrol station in Davos, looking at polar bears on the roof with a huge banner that says ARCTIC OIL - TOO RISKY.

Twenty-five activists have shut down the station, some of whom are chained to the pumps. The place is surrounded by police, but it's also been surrounded by journalists who have ducked out of the Davos meeting to hear their message about the dangers of drilling for Arctic oil.

Greenpeace came to Davos because Shell is here too.

Shell chief executive Peter Voser signed a $10 billion deal here to exploit oil shale in Ukraine, but he'll also be trying to reassure investors that the company's huge investment in the Arctic is still a good bet, despite the huge problems Shell is having up there.

So the hardy activists are bringing a different message to those same investors.

Shell Action, Davos

It's minus 15 degrees Celsius here (you might even call them Arctic conditions), but they've shut the station for several hours already.

And every minute they stay there increases their penetration into the meeting of politicians and business leaders at the World Economic Forum that's happening a few minutes up the road.

Shell Action, DavosShell was on Thursday given the Public Eye Award for the world's most unsustainable corporation.

Wherever there's a great concentration of power it's vital that the voices of ordinary people are also heard. I hope the voices of these volunteers are loud enough to reach the ears of the assembled power brokers in Davos.

We're telling them that the retreat of the Arctic sea ice – an effect of the global warming caused by burning fossil fuels – must not be exploited by oil companies to send their rigs into the newly opened waters.

We have to heed this grave warning from nature, but Shell looks at the melting ice and wants to use it to drill for the fuels that caused the melting in the first place.

I think of this as I watch the snow gently falling on the heads of the brave activists before they voluntarily end the action – having ensured the Davos meeting was so loudly interrupted by the call for Arctic protection.