On the edge of the Arctic Circle some of the biggest names in art and architecture - including Zaha Hadid, Anish Kapoor, Yoko Ono, Tatsuo Mihijima and Future Systems - recently gathered to produce an extraordinary collection of artworks made of ice and snow. See ice harvested by chainsaw, flaming vodka coursing through Hadid's ziggurat (and threatening to melt it) and Anish Kapoor get cross as his 'Red Solid' begins to look more like a pink slush puppy. Charlie Luxton investigates