Food waste is a big problem in the U.S. and (presumably) many other parts of the world as well. From Scientific American:
According to the U.S. Department of Agriculture’s Food Loss Project, we throw away more than 25 percent—some 25.9 million tons—of all the food we produce for domestic sale and consumption. A 2004 University of Arizona study pegs the figure at closer to 50 percent [...]
In the U.S., the Environmental Protection Agency has requirements in place for landfills to monitor methane emissions, and capture these emissions at higher concentrations. Again, I presume similar regulations are in place for many countries around the world.
First, is it safe to assume that methane emissions from landfills come predominantly from food waste? The only other significant source I can think of is pet waste, but I doubt the quantity would compare to food waste.
If this is true, how much of the energy stored in food waste is ultimately captured? This could be by incineration and/or conversion to biogas. Ultimately I'm interested in a global figure, but values for specific countries around the world would also be interesting.
Inspired by the question I throw compostable food into trash — how much harm do I cause?