What about a target temperature?
Now, if we're serious about ending climate change, why not agree to setting a global target temperature?
http://climate.nasa.gov/vital-signs/global-temperature/
Two decimal places looks pretty sharp to me!
If you notice, the graph is not distorted, it's linear. 1 Celsius degree changes our climate in a mix of predictable and unpredictable ways that you don't want for our planet.
Plus: there's the added problem that the changes can be exponential after a while, melted Ice melts other ice more easily, permafrost defreezing releases methane that is worse than CO2 to the atmosphere, Ice changing color, etc.