BBC: Imagine the trouble that would ensue if China resorted to desperate measures to cool its climate but the result was that the Indian Monsoon suddenly failed.
Or that India tried to head off a rise in temperatures only to find that Pakistan suffered from massive flooding.
Or that the United States took drastic action to fight global warming and then saw that great tracts of Africa were suddenly left without any rain.
These are some of the nightmare scenarios conjured up by the latest thinking...