Royal Court, SW1 ***  after the preachy hysteria of the National Theatre's Greenland ("Mum, the ice is melting and I'm really scared"), we were owed a sharpener: an affirmation that we may question the new religion which says that global warming is our fault.  Richard Bean's painfully witty play will annoy some, but even believers may enjoy briefly cocking a snook at the Monbiotocracy. Especially in a play so artfully recognisable: from the first snap of "Stop sighing Mum, you sound like you're in The archers", through references to Paxman, WikiLeaks, Gary Glitter and "Caroline Spelman's fish pie suppers", it strikes home. The first act is one of the sharpest, funniest, most engaging hours you could spend.  We start in a university department of Earth Sciences, surprised at its new fashionableness. In a clever set which shows clouds, rain and snow through skylights, Professor Kevin (James Fleet, with a moulting air) observes that arts once ruled, then Sociology , until Psychology supplanted it in the 1970s and "made bullshit respectable, which paved the way for Media Studies". Now Earth Sciences is the trendy faculty, and big business is knocking on the door offering consultancy contracts, so Kevin prefers to forget that his first book was about the coming Ic