Discussing global warming: why does this have to be so hard? | John Abraham | Environment | theguardian.com: "1. We don't know exactly how much climate change will occur. It may range from very little to a lot over the next 100 years or longer. If we are lucky, climate change will be a minor inconvenience. If we are unlucky, it will destabilize societies around the world. It is most likely neither of these extremes will occur, the future will be somewhere in the middle, but frankly we just don't know.
2. We don't know how fast it will happen. Will it take a few decades or a few centuries for some of the big changes to occur? We have a pretty good idea but we can't be certain.
3. We don't know exactly how climate change will manifest itself. How will drought/flood patterns change? How will hurricanes change? How will sea levels rise? How fast will the oceans acidify? We have educated guesses but we can't be certain.
4. It isn't clear how much of what we see is due to us and how much is just natural variability..."