[Neeek]

Except it won't, dead plants decompose and release their carbon back in to the atmosphere whether you burn it or not. Coal comes from an age where atmospheric carbon was much higher and nothing had evolved to decompose wood, digging it up and burning it means a net increase, growing something and burning it is net neutral.

[adrianN]

Technically it will, because there are geological processes that more or less permanently remove carbon from the atmosphere, but they take geological time (tens of thousands of years).