What happens when a polar bear crosses the tracks?

The train stops.

That's how it went in central England on Tuesday when fifty Greenpeace activists and a polar bear (or a person dressed like one) halted a 1,500 tonne coal train bound for the coal-fired Cottam Power Station in the town of Nottinghamshire, east of Sheffield.

While the life-sized bear blocked the path of the train, the demonstrators climbed on top of the cargo cars and began shoveling coal into sacks, which were then stamped with "Return to Sender: Vladimir Putin" and tossed aboard. According to the group, 51 percent of the United Kingdom's coal imports comes from Russian coal oligarchs.

The demonstrators reportedly used industry standard flags to stop the train. And although the police have responded, as of Tuesday afternoon the train was stalled on the tracks and continued to block the main supply route to the power station, BBC reports.

The action occurred at the same moment that world leaders, corporations, industry stakeholders and a handful of token environmental groups had convened at the United Nations climate summit in New York City in what is being billed as an 'unprecedented meeting' to discuss climate change. The action is meant to highlight the incongruities of holding these talks while the world is still so dependent on coal, and other fossil fuels, for the bulk of its energy.

"Politicians can't keep claiming to care about the future of our planet while we're hooked on coal—coal that will wreck the climate if we keep burning it," Greenpeace said in a statement. A spokesman for the demonstrators says they have enough food and water to occupy the train for the duration of the one-day summit.

"We're doing exactly what leaders in New York and here in the UK should be doing, which is to stand in the way of the massive damage to our health and climate inflicted by coal," added Will McCallum, Greenpeace UK climate campaigner.  The group is calling on UK residents to sign a petition calling on Prime Minister David Cameron and Labour Party leader Edward Milliband to stop their support of coal.

Live Twitter updates of the action can be found under the hashtag #peopleVScoal and videos of the action are available on the Greenpeace UK website.

A text comes from the coal train. "It's getting chilly but we're keeping warm by shovelling coal." #peopleVScoal pic.twitter.com/pNNS0MxR4W

— Greenpeace UK (@GreenpeaceUK) September 23, 2014