It's been pretty well established and even discussed on HN that higher CO2 levels impairs some facets of human cognition. I quick glance at some of the research

It's been pretty well established and even discussed on HN that higher CO2 levels impairs some facets of human cognition. I quick glance at some of the research suggests that this impairment can begin around ~700ppm. Having higher and still increasing atmospheric CO2 levels means indoor concentrations will make diffusion between indoor and the outdoor even slower. On the climate related side, the graph of CO2 levels for the last 10,000 years is very consistent, around 260ppm, up till recently. We should have just as concerned (or were) when it crossed 300ppm, 400ppm, etc. On a more political note, while some/most climate change deniers at this point are likely ignoring evidence - having graphs with non-zero axis can be called out as a bit misleading which makes the increase relatively larger than it actually is; visually it's at ~230% of it's normal level when it's actually 'only' 157% compared to baseline. Graph manipulation has been used to in the past to spread false information about global warming/climate change so I think it's especially important to make everything above board. It only takes a few people spreading the graph around with the axis cropped out and then everyone will cry 'fake news'.