Someone tell me what the ‘correct value’ of atmospheric CO2 is? Is it now too high, or is it too low? And how would we know?
We face two risks: Too much warming or too much cooling. The consequences of the latter are far worse than the former. So the conclusion is inevitable: It would be wiser to err on the side of too much warming, rather than too much cooling.
It is too high, by the exact amount caused by Americans driving SUVs.
And how would we know?
Nobel Prize/Oscar winner Al Gore says so.
CO2 levels of up to 2500 PPM are not considered hazardous to life. The earth has had levels this high in its history. Of course zero CO2 would cause all plant life to die, and that would eventually kill everything. I’d say as long as the level is around 200 PPM, plants can adapt. So my answer is somewhere between 200 and 2500 PPM.
Now if a final figure warms the planet from a baseline a few degrees, then I think most life will adapt. Hey if we discovered a planet that had an average temperature 5 degrees warmer than the earth presently is, we’d all want to move there, even if there weren’t any polar caps and polar bears, especially if the real estate was cheap and there weren’t any taxes.
There is no “correct” value of CO2, just as there is no “earth normal temperature”. However, if you drop CO2 below about 240ppm, photosynthisis begins to become impossible. This is well known and indisputed. In fact, real greenhouses generally add additional CO2 to the tune of approximately 1000ppm to make the plants grow bigger, better and faster. In fact some scientific studies show that increased CO2 in our atmosphere has helped plant growth planet wide. It also makes plants more efficient in water usage, and more drought resistant. The amount of CO2 in the atmosphere has varied greatly over the eons, and in fact during one of the largest ice ages was 15 times higher than today. If you were to think of all the air as your 1024x768 monitor and made the CO2 molecules black pixels, there would be 299 black pixels out of 786,432