Bonn - A UN conference to combat global warming during the next century ended yesterday with the failure of Europe and the US to break their stalemate on the issue. The 10-day conference in Bonn was intended to clear the way for a worldwide agreement on restricting greenhouse gases, seen as a cause of global warming, at a summit in Kyoto, Japan in December. It took place despite wide differences between US and European negotiators on how deeply emissions need to be curbed beyond the year 2000, with Europe's proposed targets much stricter than those suggested by Washington. Europe wants industrialised nations to agree to cut output of greenhouse gases to 15 per cent below 1990 levels by 2010. The US plan, announced by President Clinton last week, proposed merely a stabilisation of emissions at 1990 levels by 2008-12.