There are many things that people can do to reduce their carbon emissions, but changing your light bulb and many of the things are much less effective than changing your diet, because if you eat further down on the food chain rather than animals, which have produced many greenhouse gases, and used much energy in the process of growing that meat, you can actually make a bigger contribution in that way than just about anything. So, that, in terms of individual action, is perhaps the best thing you can do.

Emphasis added

Source: Supreme Master Television

James Hansen’s University of Columbia website