Agence France-Presse: A natural ice dam in southern Argentina broke open spectacularly on Wednesday the first time it has burst in winter, prompting experts to say climate change was the reason. The 60m high wall of ice from the Perito Moreno glacier that usually divides Lake Argentina in Patagonia bursts from time to time under the built-up pressure of the held-back water. The event is one of the prime tourist attractions of Argentina. But until now it has occurred in the warmer …