In his book "Just Food," James McWilliams takes down the myth of the importance of local food for slowing carbon emissions. There is a nice long list of objections, but in the end he chooses to focus on one: the importance of limiting meat consumption. The Washington Post took up that theme, noting that the average meat eater in the US contributes about twice as much to global warming as vegetarians (or fishitarians). Vegans are the best in this regard, coming in 60% below the meat eaters.
China right now is the #1 contributor to climate change, but only just barely larger than the US. That's projected to change, as the US is taking steps to curb pollution while China, as it industrializes, is on an upward swing, though the leaders at least say they're working against that. According to the news article linked to just there, emissions can be thought of as something like this:
Number of people X average income per person X energy used per unit income X CO2 per unit energy
The first one is limited by the one-child policy. No one wants to limit the second one. The third and fourth are more less measures of technical sophistication, and this is where there is a real chance to improve things. Hopefully the US and other OECD countries will share at least some of their technology with China to keep those ratios as low as possible. It will be hard for China to wean itself off of coal, a very cheap and abundant but highly polluting source of energy.