The link below leads to National Geographic and an article about the Human Condition and our impact upon the plant.  One fact listed on the page that leaps out for me is the factoid listed about Puento Hills Landfill, Whittier California which is listed as the largest landfill in the US. At this landfill gas is collected from decomposing garbage generating roughly 40 watts of energy each day which is sold to a local power company.  Closed in 2014 this landfill no longer accepts garbage but what forward thinking to put garbage to use.  I wonder how many years this landfill will continue to produce methane?

http://www.nationalgeographic.com/earthpulse/human-impact.html

This link is for the landfill:
http://www.lacsd.org/solidwaste/swpp/energyrecovery/landfillgastoenergy/puentehillsgastoenergy.asp