I’m between 4 & 5. Yes, it’s real and human-caused. But drastic emissions cuts are a cure worse than the disease. Although realistically, I don’t believe any major economic power would actually emasculate itself for the sake of preventing global warming.
My prediction is that there’ll be lots of talk, some token resolutions, some “targets” which some nations will make some effort to try to reach, a zillion exceptions to what rules do get passed (like emissions trading, exemptions for developing nations, etc.), and eventually when the technology is there a move away from coal as the main source of electricity and petroleum as the main fuel for vehicles.
In the meantime, cargo ships will be going between Europe and the Pacific Rim via the Arctic, polar bears may become extinct in the wild, snow will vanish from all but the highest mountain peaks, some areas will become dryer, some wetter, a few low-lying island chains will have to be evacuated after being drowned under one typhoon too many, there’ll be ecological and economic disruption… but it won’t be the end of the world. We’ll muddle through.
Also, a prediction I won’t live to see vindicated: sometime in the 22nd century, when human CO2 emissions drop dramatically due to technological advances, someone somewhere will sue for global warming NOT to be reversed, since they won’t want to go back to the climate they had in the early 20th century.