This isnt completely true. The biggest greenhouse gas CO2 is not a pollutant in any conventional sense. The gas is actually pumped into greenhouses to help plants grow faster, and helps plants grow in more arid environments, and reduces water consumption by plants.
So efforts to reduce CO2 might not bear environmental benefits beyond fighting global warming.
It's pumped into greenhouses because they have to be sealed to prevent heat from escaping. In nature plants aren't CO2 limited, typically they are either nutrient, light, or usually water limited; and the warming planet is exacerbating water distribution issues. Increasing CO2 does little to increase plant growth because the bottleneck is elsewhere.
Plants lose less water to the environment when CO2 concentrations are higher because they don't have to open their pores as much to effectively breath. That is why CO2 helps plants grow in more arid environments.
And CO2 is definitely not pumped into greenhouses to help them stay warm. CO2 is a very weak greenhouse gas, and the tens of vertical feet in a greenhouse couldn't possibly trap any measurable amount of heat from heightened CO2 concentrations.
The glass of a greenhouse is responsible for the 'greenhouse' effect, not CO2.
The point is that adding CO2 is necessary to solve a problem that greenhouses create, the enclosed plants deplete the available CO2 and stop growing. It's not applicable to the world at large.
In an open atmosphere plants aren't limited by available CO2, they are limited by sunlight, temperature, soil nutrients, or usually water availability. Adding more CO2 has little to no benefit for the plants.
"Has plant growth increased alongside rising levels of carbon dioxide in the atmosphere?
It turns out the answer is Yes – in a big way. A new study published in the April 6 edition of the journal Nature concludes that as emissions of carbon dioxide from burning fossil fuels have increased since the start of the 20th century, plants around the world are utilizing 30 percent more carbon dioxide (CO2), spurring plant growth."
- https://www.noaa.gov/news/study-global-plant-growth-surging-...
I mean, a little, but the closed nature of the greenhouse is still the bigger problem.
1000 cubic meters of air only has something like 150 grams of carbon in it; even if your plants in question are 95% water, you're still only talking a few kilograms of plant growth before you completely exhaust the air in an enclosed space.
> In nature plants aren't CO2 limited, typically they are either nutrient, light, or usually water limited; and the warming planet is exacerbating water distribution issues
Plants actually require extra water when CO2 levels are low, such as they are currently, which is why we see so much desertification of the planet.
High CO2 levels reduce plants need for water, reducing desertification
Increased CO2 concentrations do impare human cognition, but that is more about relatively sealed spaces with lots of people like a classroom where CO2 concentrations can be 3 times atmospheric levels or more.
So efforts to reduce CO2 might not bear environmental benefits beyond fighting global warming.