Every once in awhile, a letter is published stating that increased carbon dioxide in the atmosphere is OK because plants thrive on it. This is true but only for a short duration until the process is effectively stopped by other factors. Plants can only absorb so much CO2, and after that point, more CO2 does nothing.
Other factors limiting plant growth also include other chemicals (nitrogen, potassium, phosphorous, and magnesium, the latter for chlorophyll) and if they remain at the same level or can only be absorbed at a certain rate, then again, more CO2 is irrelevant to plant growth.
Other less understood factors also come into effect. This includes more forest fires, more soil bacterial growth, and increased fibre decay all of which contribute more CO2 to the atmosphere.
The oceans are a less understood, but perhaps dominant factor, in certain areas. They have been shown to be a large carbon sink absorbing much of the CO2 resulting in the acidification of the oceans.
At the same time, they are also a large heat sink and absorb much of the global heating. This results in the large annual decrease in Arctic sea ice as the warmer waters prevent new ice from forming until much later in the year.
CO2 becomes an impairment problem at concentrations of around 1,000 parts per million, a concentration found in poorly air conditioned offices and school rooms etc. While that concentration is still a long way off, at current rates it could be reached by the 22nd century — definitely not in my lifetime, but perhaps that of my great-grandchildren.
So yes, CO2 is critical for plant health and thus our health. But also as is true with most chemicals, too much of a good thing is simply not a good, and definitely not a better thing.
Jim Miles
Vernon
