BBC: The global recession and a range of government policies are likely to bring the biggest annual fall in the world’s carbon dioxide emissions in 40 years. The International Energy Agency (IEA) estimates that global CO2 emissions will fall by more than 2% during 2009. Measures such as emissions trading have complemented the drop in emissions as economic activity has declined. The news comes as leaders gather at the UN for a day of climate talks convened by Secretary-General …