BBC: Amphibian populations at Yellowstone – the world’s oldest national park – are in steep decline, a major study shows. The authors link this to the drying out of wetlands where the animals live and breed, which is in turn being driven by long-term climate change. The results, reported in the journal PNAS, suggest that climate warming has already disrupted one of the best-protected ecosystems on Earth. The park covers some 9,000 sq km (3,500 sq miles) in the western United …