Blah blah blah. Whatever. I think you're out-to-lunch and am tired of this particular aspect of the conversation.Wrong. It isn't a value of change, it's as if the actual temperatures had been used at the left axis. If (for example) the temperature for 2007 was 15.8C and the temp for 2008 was 15.3C, that's an actual drop in temperature.
Yes it is, and that's what it says it is. Change in temperature is what is being measured.
You're referring to the bottom axis, which is the elapsed time over which the temperature changed.
THe graph demonstrates changes in temperature over time. It does not demonstrate rate of change.