[korpiq]

For that, I'd be interested in Paulownia trees for their fast growing speed, and thus (I assume) faster CO2 reduction rate.

1) https://en.m.wikipedia.org/wiki/Paulownia_tomentosa is also rapid to spread, which may turn out too rad for local flora or neighborhood politics thereof, while

2) https://en.m.wikipedia.org/wiki/Paulownia_elongata seems not to spread on its own and thus may need active help for that.

You'll end up with a lot of soft wood from these relatively fast (10 years?). That should be used in some way that does not release the CO2 back.

I have no studies nor experience in biology nor gardening and all of this is only based on what I've been reading on the internet.

[abgfm]

The most appropriate trees for an area are the local ones and with a view to Climate Change, the local species with good adaptability to climate change characteristics (need less water, can rezist temperatures variations, etc.). Pawlonia is being pushed/marketed heavily on the internet due to some superficial/mercantile characteristics (fast growth, big foliage), but besides that, in the agroforestry/agroecology academia, Paulonia is known to be just a marketing buzz, and a relatively dangerous one.