"This global warming is killing me!" kvetches a sunbathing hippo in Ice Age: The Meltdown. And with a thawing glacier threatening to flood the valley where he and his fellow prehistoric critters reside, that's not far off the truth. Reuniting the mismatched heroes from its hit predecessor, Carlos Saldanha's mix of race-against-time action and eco-friendly propaganda is actually an improvement on the original, not least for giving its funniest character - acorn-hunting rodent Scrat - a lot more to do.

For the most part, though, the story focuses on Manny the mammoth (Ray Romano), Sid the sloth (John Leguizamo) and Diego the sabre-toothed tiger (Denis Leary), whose long trek to safety is complicated by the arrival of a female mammoth (Queen Latifah), two playful possums and a kettle of singing vultures. Along the way Syd is crowned the king of a secret sloth society, while Diego learns to confront his fear of water - not that he has much choice with a billion tons of the stuff heading his way.

"A STERLING JOB"

CG 'toons no longer being the novelty they once were, it's harder to be impressed now by slick visuals and 360° panoramas. That said, the Blue Sky team who gave us Robots do a sterling job evoking this defrosting world, while the wisecracking voice cast capably complement Scrat's virtually silent escapades. A shame, though, the writers felt the need to incorporate anachronistic and largely unamusing nods to Jerry Maguire and R Kelly, or milk sympathy with a mawkish mammoth flashback.