CO2 and forests

CO2 helps plants grow faster, but it is complex in that there are often other limiting factors. As you eliminate some, others become more prominent. A limiting factor for trees is often water or a shortage of one or more of the big three fertilizers: Nitrogen, Phosphorus and Potassium. Humans have added CO2 to the air, but also added Nitrogen, Phosphorus and Potassium, so much that they are sometimes pollutants. It might be that we have lucked onto something good out of potentially bad if increased CO2 levels allow faster growth to suck up some of that excess NPK. This is unlikely to apply as much to tropical forests as temperate ones, however.

Throughout earth’s history, CO2 levels in the air have fluctuated but have generally been dropping until recently. I mean, we are talking geological time. The drop has been happening for the last 200 million years, when CO2 levels were 4-5 times as high as they are today. At this time, earth was universally warm and great forests of giant ferns grew all the way to the arctic. I have always been interested in such things, but there is probably no practical use for this knowledge.