[copperred]

At first glance, it seems attractive to put a giant CO2 sink in urban areas where it can reduce those pesky greenhouse gasses. But on closer inspection you will find that they actually pump CO2 into these facilities to improve crop growth.

[avip]

>a giant CO2 sink

Just to set the numbers straight:

  Very clean US city: 10^10 [Kg*CO2/year]
  Absurdly hefty tree, in his prime: 10^2 [kg*CO2/year]
  vertical farm: _____

Such is the impact of the giant sink.

[copperred]

It's not a sink.