[tcpzhqsq] Global warming

The question of global warming breaks into four separate questions.

1. Is the earth warming?
2. Do greenhouse gases cause global warming? In particular by the amounts we see.
3. Is the amount of greenhouse gases in the atmosphere increasing?
4. Is the increase in greenhouse gases caused by human activity?

If the answers to the previous four questions are positive, then it logically follows that global warming caused by human activity.

Critics of global warming neatly break into four camps, one for each question. (There is actually a fifth category of people who acknowledge that global warming is caused by human activity, but disagree with proposals to stop it, namely curbing greenhouse emissions. )

It is possible to doubt global warming, thinking the evidence is inconclusive for one or more of the questions above, yet still support trying to curb carbon dioxide emissions. You can take the mentality of a scientist or of a engineer/adventurer. For the scientist, the way to gain conclusive evidence is to perform the experiment, forcibly changing greenhouse emissions by human activity and measuring what happens. The engineer/adventurer can look upon the project like climbing Everest, exciting and ambitious: We do it simply as a test to see what we as a civilization are capable of.