While I don't want to spoil the joke (but I will) and I hate techno-optimist solutions that displace actual solutions for our biosphere: supposedly, Belgrade is such a dense concrete hell that trees aren't viable solution (at least in the short term).

There is some rumbling that liquid trees are not the solution to the real problems caused by large-scale deforestation, nor does it reduce erosion or enrich the soil. However, much of this wrath is misplaced as Liquid tree designers say that it was not made as a replacement for trees but was designed to work in areas where growing trees would be non-viable. Initiatives like Trillion Trees are laudable, but there is something to be said for the true utility of this tiny bioreactor. The fact that they can capture useful amounts of carbon dioxide from day one is another benefit for them. Such bioreactors are expected to become widespread in urban areas around the world as the planet battles rising carbon levels in the atmosphere.

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