Perpetual Motion Machines and Increased CO2

2. what effect would increased carbon dioxide have on plants? If more trees are planted, would this stand to have any effect on atmosphere levels?

Increased CO₂ makes it easier for plants to grow.

Planting more trees gives more scope for photosynthesis to occur, altering the CO₂:O₂ relationship in the neighbourhood of each tree in the direction of O₂. It will also increase the humidity as well, as plants naturally transpire water from the surrounding soils. The leaf canopy produced will reduce the availability of light at the soil surface, which may in some cases have a detrimental effect on flora there and the fauna that depend on them.

"1. what energy principle precludes the possibilty of a perpetual motion machine?"

The Second Law of Thermodynamics is the stumbling block that brings down all known schemes of PM, Free Energy,Zero Point Energy, etc. ad nauseum.

The laws of thermodynamics can be summed up as (A) You cannot win; (B) You cannot
break even: and (C) Sure, the dice are crooked, but this is the only game in town.

The laws of thermodynamics can be summed up as (A) You cannot win; (B) You cannot break even: and (C) Sure, the dice are crooked, but this is the only game in town.

Beautiful!