1. "Kennedy insisted that the problem is that much of the space that was used for cocoa plantations is no longer there, because the farms are being chopped down and turned into rubber plantations as they get a better yield."
2. "...we need another Earth if we carry on at this rate,"
Is this supposed rate of decline he uses to forecast into the future something permanent though?
Is the problem they can never go back to producing cocoa once they've switched to rubber?
Because if it's not, when chocolate becomes more expensive and thus profitable (yield-wise) than rubber plantations will just go back to cocoa, ie bring the price down.
IE changing the current rate of cocoa decline.