HN's community moderation tools seem to fail at times, so I'm responding to ssearyus's comment that is marked [dead]:

ssearyus: At the risk of being immediately downvoted, let me point out that a 250ppm CO2 level is borderline disastrous for plant life -- at 180ppm, plants would starve globally. The increased CO2 levels in recent years (slightly added to by human activities) is immensely helpful for drought-resistance, as stomata do not then need to open as much to get sufficient CO2 with the result that they transpire less water. The above, and the fact the by far the most important GHG in the atmosphere is water vapor (CO2 is comparatively a rounding error) should give reasonable people pause for thought.

My response: I think there's something you're trying to say, but it doesn't come through clearly in these many points.

- 250ppm is not disastrous for plant life. That's around preindustrial levels of CO2 (280ppm) and plants did just fine

- What do you mean by "starve" here regarding 180ppm?

- And why are you talking about 250ppm and 180ppm specifically? No one is talking about 250ppm or 180ppm as targets (or maybe you are?)

- Water vapor is indeed a greenhouse gas, and contributes to warming. But it's best thought as an accelerant. Warmer temperatures bring more water vapor bring higher temperatures, bring more water vapor etc etc. The rise of carbon dioxide in the atmosphere is so important because it trigger in many ways a feedback loop, one of which is rise in water vapor as a greenhouse gas. The feedback loop caused by temperature/water vapor is one of the reasons we need to be very careful with our human-made emissions.

- "CO2 is comparatively a rounding error": Whether by mass or volume, CO2 is not a rounding error by comparison to water vapor. There's roughly 4 to 6 times the amount of water vapor as CO2. I wouldn't call 25% a rounding error. Maybe there's something I missed here.

- And when you say water vapor is "by far the most important GHG in the atmosphere", does that mean you're working on lowering water vapor levels in the atmosphere? Or what are you working on regarding solving for this? Maybe something with airplane cloud formation trapping heat?