We are trying not to get too deeply into it with climate change deniers. It is often a waste of time and generally doesn’t result - especially on social media - in a productive discussion.
Nevertheless, sometimes in the context of talking about CDR, one encounters deniers who argue that no CDR is necessary because no global warming exists.
They use a few of the same arguments in different versions. Here is some information about those that are relevant in the context of CDR.
Picture source: Unsplash, Md. Hasanuzzaman Himel
This is an argument people seem to actually believe (rather than just use as an excuse): plants need CO2 and more of it is better for growth. This is why greenhouses artificially increase the concentration of CO2 to 800 - 1500 ppm.
The source below explains why this is an oversimplification and logical fallacy quite well, but in short:
too much of a good thing can be a bad thing and only focussing on CO2 as “plant food” neglects to take other important factors (water, other nutrients, etc. into account.
Source: More CO2 in the atmosphere hurts key plants and crops more than it helps