Yvo de Boer, head of the U.N. Climate Change Secretariat, expressed concerns that the Bali climate talks could collapse if 190 nations do not quickly resolve disagreements that are hindering the start of negotiations for a new global warming agreement. The talks, which have brought together over 10,000 delegates on the Indonesian island, are stuck on the specifics of launching negotiations for a climate deal to follow the Kyoto Protocol. De Boer warned that failure to make progress could lead to the collapse of the entire process. In the ongoing discussions, the United States, Japan, Canada, and Australia are pushing back against the proposed guideline for wealthy nations to reduce greenhouse gas emissions by 25 to 40 percent below 1990 levels by 2020 as a reference point for future negotiations. The European Union, on the other hand, supports this range to demonstrate that affluent countries should take the lead, and has criticized Washington for obstructing progress in Bali. This target was included in a recent draft on Thursday as part of terms for discussions aimed at preventing food shortages, droughts, sea level rise, and the melting of Himalayan glaciers. Portugal's Secretary of State for Environment, Humberto Rosa, expressed disappointment that the United States is holding up global action on this issue. Portugal currently holds the rotating EU presidency, and Rosa is the chief negotiator for the EU at the Bali talks. "The United States has recently adopted new terminology such as 'engagement' and 'leadership,' but simply using words is inadequate. We require tangible action. This is the primary obstacle," he informed Reuters. The U.S., not a participant in the Kyoto Protocol, argues that setting guidelines would prematurely determine the results of negotiations. Additionally, it contends that the 25-40 percent range is founded on limited scientific research." De Boer stated that negotiations needed to resolve all remaining conflicts by midday on Friday to allow for translations into the six official U.N. languages. U.N. climate talks typically continue late into the night on the final day. The Kyoto Protocol requires 37 industrialized nations to reduce their emissions from 2008 to 2012. Developing nations, including China and India, are not bound by these restrictions, and President George W. Bush withdrew from the agreement in 2001, citing potential harm to the U.S. economy and lack of targets for developing countries. The United Nations aims for all countries to agree on a successor to Kyoto by late 2009 to allow for ratification by the end of 2012 and provide clear guidelines for investments in clean energy technology. China is pushing for negotiations on a new international agreement to continue beyond 2009 in order to allow a new American president to participate. However, not many other countries support this idea. Norwegian Prime Minister Jens Stoltenberg emphasized the importance of limiting global temperature increase to 2 degrees Celsius and ensuring global emissions peak by 2015. Our actions will be evaluated by future generations. He also mentioned that the wealthy will need to bear the majority of the expenses in assisting impoverished nations in reducing greenhouse gas emissions.