There are huge benifits to the environment in legalization.
The syndicate growers would leave the forests and take their water diversions, pesticides and fertilizers with them.
People would not need to grow indoors greatly reducing the amount of energy being wasted by folks growing indoors just to hide it.
The smugglers would not be using fuel to bring marijuana across the border.
These are just a few of the benifits I can think of in addition to the myriad displayed above.

Time to end the prohibition.
rudy2010 Reviewed by rudy2010 on . The Industrial Benefits of the Cannabis Plant The industrial and agricultural benefits of the 'hemp' variety of the cannabis plant are almost unreal. There are over 25,000 industrial uses of the cannabis plant. --Green Fuel (Pun intended): A bio diesel fuel made from the hemp plant emits 80% less CO2 than fossil fuels, which generates less greenhouse gases and does not cause acid rain thus slowing global warming. Hemp fuel is found to be 10x less toxic than salt, and is as biodegradable as sugar. --Land Saving: 1 acre of usable hemp Rating: 5