In article , Norman Wells
writes

Atmospheric extraction is totally unfeasible. Have you _any_ idea how
big the atmosphere is, and how small in comparison any man-made
extractor would be?

Yes, at surface density, it is equivalent to a uniform layer a little
less than 5 miles thick over the surface of the globe, some 200million
square miles, making the atmosphere approximately 1billion cubic miles
at surface density.

How many would we need do you think?

That depends on how fast you think we need to do it. The argument,
whether you believe it or not, is that we have managed to cause the
problem simply by a few hundred large CO2 producers over a couple of
hundred years. So a similar number of capture units should be capable
of sweeping it all up in a similar time, probably faster.

At a few hundred feet per minute a single atmospheric extraction unit
with a scrubber area of only 1 square mile, would take around 20,000 to
remove all CO2 from the atmosphere, so a distributed system of 50 such
systems around the planet would clear the problem in less time that it
took to create it in the first place - and we don't WANT to get rid of
all of the CO2 or we'd be in for a very cold future.

And wouldn't it be better to use trees as we always have?

No, because trees rely on natural air movement to access the atmosphere,
not forced air movement. And they tend to decay or be burned, releasing
their captured CO2 in the timescale.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)