Greenland, the National Theatre's state-of-the-planet pageant, places its audience in a shifting, uncertain landscape and asks how it intends
to react to climate change. We could flagellate ourselves with collective guilt, do our recycling or become tent-dwelling, office-occupying eco-warriors; we could deny that it is happening, fall into despair or get on with our lives in a responsible manner. After two hours, I still wasn't sure of my answer.

Bunny Christie's design is deliberately invasive. Guillemots fly around the auditorium's walls. At the end, torn-up pieces of paper, on which protocols from the Copenhagen climate summit are printed, snow down on us. And it's not over when it's over. In the lobby, a band is playing, and the DJ from the pretend radio station who impedes our progress to the bar on the way in is still soliciting our opinions (one suggestion on press night: climate change is God's way of bringing us together).

Even without the polar bear that crosses the stage - was it recycled, in an ecologically responsible touch, from His Dark Materials? - it would be quite a show. With four writers and a cast of 15, this is the National's all-singing, all-dancing response to global warming. The director, Bijan Sheibani, has gone to the extremes of the earth, one might say, to ensure that we are not bored. It's no Enron, but it's never dull.

Yet, if art is life reordered until it makes sense, this play fails. It neither makes sense of the science of climate change nor argues a fit response. We can only guess which of the playwrights - Moira Buffini, Matt Charman, Penelope Skinner and Jack Thorne - wrote which of the stories that weave in and out like plots in a soap, but their narratives frequently pull us towards different conclusions.

We are tempted by the lonely life of a disinterested scientist, as represented by the Arctic observer who pretends that he doesn't love the guillemots whose declining numbers he counts but who clearly does. He is joined by his younger self, the London schoolboy of 40 years earlier, whom we meet being given the third degree by a bullying Oxbridge don at his admissions interview. The proper study of mankind is geography. But an equally sympathetic narrative follows a young researcher from Ed Miliband's office (the play is set when Labour was still in power, which, it must be said, somewhat reduces its urgency) who visits a hermit-like climate-change scientist. The scientist scares her with a prediction of a 3.5° temperature increase and the extinction of a sixth of all life on earth.

As a politician and pragmatist, she chooses not to believe him. "It's not a religion, Phoebe," he tells her. "Of course it is," she replies. But this doomsayer, whom she bundles off to Copenhagen, loses enthusiasm for his own prophecies as he falls for her, becoming agitated by more immediate concerns. "Do you fancy him?" he asks of Miliband. "No, believe me, I've tried," she assures him. As the summit reaches its climax, so do they. Perhaps the truly heroic thing in the face of annihilation is to take the optimistic gamble of loving someone.

I wonder, too, if whoever wrote the story of the young woman who chucks in her sports science degree in favour of an eco-camp, a messianic hippie and direct action was not of the devil's party without knowing it, or, at least, of her parents' party. As this student rants at them from a supermarket trolley hoisted on wires above the stage, it is hard not to wonder if she is off her trolley as much as she is in one.

Serving the believers' cause no better is a whiny, right-on, Saffy-style daughter who berates her mother so much that she contorts with guilt about her weekly Starbucks coffee. We are also presented with an inarticulate yoof who compares our materialist excess to his profligate use of a loo roll, forgetting that he will soon be down to a single sheet and in the you-know-what. And then there is the strange visual comparison of human survival with winning the jackpot on Deal or No Deal.

It feels wrong to accuse a play of containing too many ideas, but someone should have decided whether Greenland was an examination of Britain's mental state, agitprop or an Al Gore lecture (in which case, the alarmist stats of a fictional scientist would be inadmissible).
Nigel Lawson, a climate-change denier whose name is invoked in the production, will be speaking at the theatre on 4 April. For all its brio, Greenland, which earns its place in the new era of eco art that we are surely entering, is a less formidable opponent than he might have feared. In taking it apart, his only problem will be figuring out where to start. l

“Greenland" is on until 2 April. For more details, visit: nationaltheatre.org.uk
Andrew Billen is a staff writer for the Times