This calculation depends on the “level of emulation” expected to be necessary for successful WBE. Sandberg and Bostrom (2008) report that attendees to a workshop on WBE tended to expect that emulation at the level of the brain’s spiking neural network, perhaps including membrane states and concentrations of metabolites and neurotransmitters, would be required for successful WBE. They estimate that if Moore’s law continues, we will have the computational capacity to emulate a human brain at the level of its spiking neural network by 2019, or at the level of metabolites and neurotransmitters by 2029.

The roadmap does estimate that we could do a spiking neural network emulation in 2019, but the target dates for the more detailed levels of emulation come later: 2033 for the electrophysiology level, 2044 for the metabolome level. The 2029 estimate is right if you only look at the demands for memory (on page 79), but the demands are higher for processing power (on page 80).