As the final negotiating session before next month"s United Nations climate change conference in Copenhagen concluded today, the world body"s top U.N. climate official called on governments to deliver on a strong international agreement to tackle global warming. "Copenhagen can and must be the turning point in the international fight against climate change-nothing has changed my confidence in that," said Yvo de Boer, Executive Secretary of the U.N. Framework Convention on Climate Change (UNFCCC). "A powerful combination of commitment and compromise can and must make this happen," he told a news conference in Barcelona, the site of the final round of talks ahead of the 7 to 18 December meeting in the Danish capital. In Copenhagen, governments are expected to agree to a successor to the Kyoto Protocol, the 1997 treaty which expires in 2012. More than 4,500 negotiators from 181 countries participated in the five-day gathering, during which progress was made on the issues of adaptation, technology cooperation, reducing emissions from deforestation in developing countries and mechanisms to disburse funds for developing countries. Little progress was made, however, on mid-term emission reduction targets of developed countries and financing for developing countries, according to a news release issued by the UNFCCC. These are two key issues that would allow poorer countries to limit their emissions growth and adapt to the inevitable effects of climate change. "Without these two pieces of the puzzle in place, we will not have a deal in Copenhagen," said de Boer, adding that "leadership at the highest level is required to unlock the pieces."