Last Updated: Thursday, 24 May 2007, 14:13 GMT 15:13 UK Japan's Prime Minister, Shinzo Abe, has said the world should halve emissions of greenhouse gases by 2050. It is the first time Japan has set a firm target to replace the present Kyoto protocol, which expires in 2012. The plan is believed to be less demanding than other proposals from European countries such as the UK. But Mr Abe said it was