The initial UN special session on climate change, held on Tuesday, emphasized the responsibility of wealthy nations in reducing greenhouse gases. Economist Nicholas Stern highlighted the need for both developed and developing countries to take part in a global effort to reduce human-made emissions. Stern proposed a global target of a 50 percent reduction in greenhouse gases by 2050, with wealthier nations expected to make even larger cuts, aiming for around 75 percent reductions due to their historical emissions and greater access to resources. Stern, a former head of the British government's economic service now at the London School of Economics, suggested that responsibility for financing cuts in emissions in other countries may be necessary. British Prime Minister Gordon Brown also emphasized the need for industrialized nations to take greater action on climate change, acknowledging the disproportionate impact on the world's poorest populations. Sunita Narain, director of India's Center for Science and Environment, criticized the lack of real action from political leaders in addressing climate change. John Holdren, an environmental scientist at Harvard University, stated at a gathering that global climate change is responsible for droughts, floods, rising seas, and more intense storms, and cannot be attributed to natural climate variability. The United States, a major emitter of greenhouse gases, did not make a statement at the recent sessions and has rejected specific targets for reducing emissions, citing potential harm to the economy. Instead, Washington has advocated for voluntary rather than mandatory cuts in emissions. President George W. Bush, along with leaders from other industrialized nations, agreed in June to make significant reductions in climate-warming emissions and to negotiate a new global climate agreement to replace the Kyoto Protocol after 2012. The two-day climate meeting at the United Nations is the first of its kind in substance and style, concluding on Wednesday. The event is environmentally friendly, as any emissions produced from air travel and the UN Headquarters building in New York are counterbalanced by supporting a biomass fuel project in Kenya.