Several times, this blog has referred to the relationship between plant life and carbon dioxide in the atmosphere. it has come to my attention that one or both sides of the climate change question may have interrupted possible changes in the tree line to be the result of climate change. To make sure I have not contributed to that erroneous conclusion, I would like to restate my understanding of the tree line and its relationship to carbon dioxide.
The tree line is, largely but not solely, determined by the highest altitude CO2 will reach in the atmosphere without the aid of wind currents or other factors such as jet engine exhaust.. Trees require a great deal of CO2 so when CO2 levels get weak, the trees do not/cannot grow. It is this location in the atmosphere that is commonly called the "tree line".
That altitude has to do with the molecular weight of CO2 not the amount of CO2 in the atmosphere. However, if climate change advocates succeed in reducing the overall amount of CO2 in the atmosphere, it is possible for the density of vegetation at the tree line to be reduced. It will not reduce the altitude to which large plant life will grow but, like dry areas, if there is not enough CO2 to sustain tall, well-formed trees, then they will not grow. Water or the lack there of also can play a huge part in the appearance of the tree line.
As stated before, CO2 gas and other carbon based gases are not to be blamed for climate change. CO2 levels may increase the density of vegetation but for the most part, high concentrations of CO2 gas are located in areas far from areas of dense vegetation.
As always when writing to those with limited scientific knowledge it is hard to know exactly how much explanation is needed. I hope this clarifies this topic for those who might be unfamiliar or confused in this regard.