Tonnes per hectare

using that CSIRO paper mentioned ealier algal ponds produce 110t/ha/yr

Okay. Lets aim to have all historical human emissions out of the atmosphere in 100 years (ignoring ongoing emissions at this stage; eggh)

So 780 billion tonnes X 1/1.5 = 520 billion tonnes

520 billion / 110  (tonnes/hectare) x 100 (years)= 50 000 000 hectares. 

Alot....

how much?