I'm reading Catastrope Ethics by Travis Rieder. This passage drives home why we need to question how politicians talk so promisingly about negative-emissions tech that sucks CO2 from the air:

"The other category of negative-emissions technology avoids at least the land-use problem and is popular among the more techno-optimistic, as it does something that sounds borderline magical: it sucks CO, directly from the air and returns it to the ground. There's only one problem, which is that it doesn't yet exist in a scalable form.

What scientists have come up with so far are proof-of-concept models that show initial promise but that have very real drawbacks.

Consider, for instance, Orca, which is the largest carbon-capture plant in the world, located in Iceland just outside Reykjavik. This facility is instructive for many reasons. First, despite being the largest plant in the world, it will only capture about 4,000 tons of CO2 annually. And while that may sound like a large number, remember the scale that we're talking about: the all-time anthropogenic CO2 budget is 3.67 trillion tons. On average, humanity emits more than 1,250 tons of CO2 per second. What that means is that our largest plant to date, running around the clock for a year, will capture about 3 seconds' worth of humanity's emissions."