Biology lesson
Re: "No CO2 miracle", (PostBag, Oct 8).
I'm at a bit of a loss to understand Michael Setter's assumption that I don't eat my greens, but I have to acknowledge the rest of his letter makes more sense than I usually give him credit for. It seems that my long-held conviction that photosynthesis operates at a rate determined by available moisture and sunlight, and is not related to the atmospheric concentration of CO2, is wrong.
I apologise to Anna Aarts for my somewhat haughty dismissal of her factually correct science in this regard, though I doubt she has fled the country in high dudgeon as Khun Michael fears.
In the interest of maintaining perspective however, we have to keep in mind the apparent " greening" of the planet recorded by satellites is neither a wave of new vegetation in previously barren areas nor entirely a result of the increase of CO2 in the atmosphere.
While the science suggests existing vegetation may proliferate more quickly because there is more available CO2 in the air, some of the new "greenery" recorded from space, as in the deserts of China and India, is due to the deliberate planting of large areas of trees specifically to prevent those arid areas from spreading.
Before we get too warm and mushy about our good friend CO2, it is also worth noting that the Sahara, Kalahari, Simpson and Gobi deserts, among many others, continue to expand in area, due in part to the global warming caused by man-made carbon dioxide.
It's a fascinating topic and much has happened since I last sat in a biology class. For those interested in the topic, or keen to follow it further, Google has a lot to offer.
