The climate talks in Lima, Peru, are entering their final week, with few hints whether a newfound optimism that marked the start of negotiations will ultimately translate into a reality that would rein in climate change. Convened by the United Nations, the talks aim to craft the framework for an international accord to curtail heat-trapping emissions and adapt to changes already occurring on the planet. The final agreement is due to be signed in Paris next December. Despite more than 20 years of discussions about what nations must do to contend with climate change, the world’s emissions of carbon dioxide and other heat-trapping gases are higher than ever, as negotiations have continued to snag on the contradictory priorities of different countries. The latest round in the discussions began last week with fresh momentum, in large part thanks to steps the US took last month, including a major deal with China to curb emissions and a $3-billion commitment to help developing nations fight climate change. Yet over the days since the Lima conference began on 1st December, clashes have flared between developed and developing countries over issues such as whether emissions cuts should be mandatory and how much money rich countries should provide to help poor nations cope with damage from climate change. The question remains whether the brinkmanship will give way to an agreement by the end of the week on key issues, the most pressing of which is ground rules on emission-reduction pledges that countries are to make early next year. The window is closing fast for countries to cut greenhouse gases enough to avert the greatest global temperature increases and natural disasters associated with them, climate scientists and organisations such as the World Bank warn. The current round of talks would shape efforts to address climate change after 2020. Poorer nations are struggling to nail down significant, steady funding from industrialised countries to help them cope with the damage from climate change and to develop their economies without relying on fuels such as coal.