Global warming/debate/position quiz

=The Global Warming / Climate Change Position Quiz= The following questions are an attempt to itemize all of the significant areas in which disagreement might exist so that parties debating this issue can focus in on resolving their actual disagreements rather than what they imagine the other person might believe. It should also be helpful in preventing discussion participants from shifting position without notice.

This quiz was originally posted here.

Quiz

 * 1. Is there any evidence that global temperatures have begun rising sharply since the beginning of the industrial age?
 * 1a. If there is evidence, is it fairly strong/conclusive?
 * 2. By approximately how many degrees Celsius would global temperatures need to rise in order to cause severe* consequences?
 * *severe enough that it would be worth putting forth global-scale effort towards reducing the rise before it happens
 * 3. Approximately what level of oil prices (expressed as a factor of current prices) would it take to cause a food crisis in the US?
 * 4. In what time frame (a decade? a generation? a century? never?) is this level of increase likely to happen?
 * 5. Is there any reason to think that accumulation of carbon dioxide in the atmosphere has reached unprecedented levels?
 * 6. Is there any reason to think that unusually high levels of carbon dioxide would cause serious ecological problems?