Guardian: My, how things have changed! In 2000, scientists from the Worldwatch thinktank in Washington teamed up with the UN to spot the greatest threats to the planet over the coming years. Top of the list was ecosystem collapse, such as deforestation and the demise of corals; second were health and diseases, such as Sars and Aids; and third was global poverty. The world’s top environmental analysts gave climate change only four paragraphs in an eight-page essay – little more than malaria, trade, air …