Compost
Composting is the process of returning waste food directly into a humus-rich soil ammendment or fertilizer. The process can be done on a small scale or a large scale, and for small scale composting, you don’t even need a backyard. This process, and the related vermiculture or vermicomposting (worm cultivation), can be done by those living in apartments!
How is composting a solution to global warming? In several ways. First of all, it reduces the amount of trash in the waste stream. All trash requires mechanical, fossil-fuel-driven energy to transport and process, whatever that processing is. Second, the use of the end product on soil both increases the productivity of that soil (an adjunct benefit) and does so without the use of commercial fertilizers, which need to be manufactured, packaged, stored, transported, sold, and transported home… and then include the disposal of the packaging of that fertilizer… all of which is based upon fossil fuel use.
So composting is a fossil-fuel avoidance strategy for sure, and supports sustainability directly as well. It has another collateral benefit, more powerful perhaps still. It increases your awareness and involvement, it makes you feel good, providing direct positive feedback for your efforts, and helps you integrate more and more paradigm shifts in your lifestyle, which is the big prize in fact.
Here are some useful links on composting. There are thousands more online and in libraries (remember books!). But BEWARE of sites that hype lots of things to buy, especially large, complex, fancy composting bins. These are usually plastic, take significant transportation energy, come packaged extensively for protection en route, and require disposal someday as well. All of this can undermine the benefit of the composting they will support. Remember, the real goal is to get along with less stuff!