That's what millions are asking after hearing Morning Edition's top of the hour news segment (sorry, no link). The segment referred to negotiations over emissions caps for greenhouse gases. It said that China argued that it should not be subject to the same rules that apply to other rich countries.
China was presumably making the argument that it was not a rich country and therefore should not be subject to the same rules as rich countries. While China's economy is now larger than the U.S. economy on a purchasing power parity basis, since it has four times the population, on a per capita basis it is about fourth as rich. This means both that it has fewer resources to cope with the problem and that the average Chinese person is far less responsible for global warming than the average person in the United States.
It is also worth noting that in an era of secular stagnation, like the one we are in now, spending to slow global warming would increase employment and output. It is not a drain on the economy.