An old rift between rich and poor has reopened in U.N. climate talks as developing countries look for ways to make developed countries accept responsibility for global warming — and pay for it.

With two days left, there was commotion in the Warsaw talks Wednesday after the conference president — Poland's environment minister — was fired in a government reshuffle and developing country negotiators walked out of a meeting on compensation for climate impacts.

The question of who's to blame for climate change is central to developing countries who say they should receive financial support from rich nations to green their economies, adapt to shifts in the climate and cover costs of unavoidable damage caused by warming temperatures.