Delegates from some 192 nations meeting this week for the latest round of UN climate talks will be faced with a difficult challenge: how to keep the ball rolling on agreeing a successor to the Kyoto Protocol in the midst of a global economic emergency.

The convention, which runs 1–12 December in Poznan, Poland, marks a halfway point between negotiations that took place in Bali last year and those at the end of 2009 in Copenhagen, where the international community is expected to approve a new deal on climate change to take effect from 2013.

Globally, greenhouse gas emissions are rising. Forty industrialized nations that signed the Kyoto Protocol have increased their output 2.3 per cent from 2000 to 2006. Yet the world remains fragmented on how far to reduce emissions and how to do so equitably.

Those questions will not be answered in Poznan (page 164). Even the modest ambitions of the talks — to settle how to finance emissions cuts and aid adaptation in developing countries — are now likely to be eclipsed by financial woes, shifting the focus to less costly issues such as technology transfer.

What can be expected to emerge from Poznan, however, is greater clarity on how various players will position themselves in Copenhagen. Over the coming week, the world's environment ministers will pore over a document that maps out national priorities for a final emissions control treaty.

Since the last round of talks in Bali, positions have shifted and in many cases have unified. At Japan's G8 summit in July, a group of the world's emerging economies came together for the first time in calling for more stringent binding emissions targets from the industrialized world. Meanwhile, 53 African countries have signed an 'Algiers declaration' that unites them as a bloc in the forthcoming talks, a move intended to give them more clout in the final treaty. And previously reticent China is expected to come to the fore, having recognized its role as the world's leading greenhouse gas emitter. Europe, on the contrary, long heralded as climate change champion, is starting to experience discontent among its ranks, with Poland demanding a compromise on the cost of CO2 emissions under the proposed expansion of the EU emissions trading scheme.

Unquestionably, the most meaningful shift has been the election of Barack Obama as US president, a change that brings renewed energy and hope to the UN process. How the Obama administration will position itself internationally on climate change remains to be seen, however, as President Bush is still holding court during the current talks. And with the United States in transition, the world is unlikely to move closer to resolving key issues in the coming week. But the emerging unity among other nations will put the pressure on the US come January — and that could just be enough to secure a global deal in Copenhagen.