Gavin and Jim want you to believe that Scenario B is the right one, because Scenario B’s predictions didn’t suck quite as bad as Scenario A. But it is worse than it seems.
The CO2 curve is an exponential curve. Joe Romm described it as being “super-exponential” The curvature is upwards, which means that the second derivative is positive.
The graph below adds tangents, showing how the slope is getting progressively steeper.
Jim and Gavin naturally assume that their audience is gullible, and have been pushing the Scenario B meme. So let’s look at what Hansen actually wrote in his 1988 paper.
Scenario A assumes exponential growth of CO2. Scenario B assumes linear growth, which clearly is not the case. Scenario C assumes no growth.
The graph below shows what Hansen’s three scenarios would have looked like. Scenario A in blue, Scenario B in green, and Scenario C in red.