If you want to quantify the environment impact of your diet...

While doing research as an effort to find more detailed scientific data that may help estimate exactly how much impact on environment there is for going hybrid and going veggie, I came across a good blog Vegans vs. Hybrids. Then it got me searching for the report Diet, Energy and Global Warming that it referenced to. That blog and the report are really good sources for me to understand the issue from a more quantitative perspective. However, as the report was written back in 2005, and the blog was posted in 2007. I decided to look for more recent data. Then I found the following article that  I would like to share with all of you. The paper was published more recently than the aforementioned two in May 2009 by American Journal of Clinical Nutrition and the title of the paper is Diet and the environment: does what you eat matter?

To be fair, I must say I have no idea about the reputation of this journal, but I do find this paper a very interesting read, and very easy to follow for anyone with little or no medical background. As I am seeking more scientific data on the issue of environmental impact from our diet habits, this paper provides the exact source of knowledge I am looking for. As stated in the abstract,

...The literature supported this notion. To accomplish this goal, dietary preferences were quantified with the Adventist Health Study, and California state agricultural data were collected and applied to state commodity production statistics. These data were used to calculate different dietary consumption patterns and indexes to compare the environmental effect associated with dietary preference. Results show that, for the combined differential production of 11 food items for which consumption differs among vegetarians and nonvegetarians, the nonvegetarian diet required 2.9 times more water, 2.5 times more primary energy, 13 times more fertilizer, and 1.4 times more pesticides than did the vegetarian diet. The greatest contribution to the differences came from the consumption of beef in the diet. We found that a nonvegetarian diet exacts a higher cost on the environment relative to a vegetarian diet. From an environmental perspective, what a person chooses to eat makes a difference.

Note that, since the research work carried out by authors in this paper require a big enough sampling space to establish their findings as statistically true or convincing, with 34000 California Adventists participating, the data collected there may be 2 to 3 years old (I was looking for the age of the data in the paper but failed to find it, I probably have missed). However, I think the data there are still fresh enough to provide some guideline this this context. Note that this paper is based on the authors work limited only in California residents. It is important that, while data will vary drastically among different areas where the trend of the environmental impact is expected to remain the same.

Allow me to quote the following analysis from this paper to conclude my post,

As it is pointed in the paper,  "The outcome of our studies provided evidence for the much higher ecologic cost of an animal-based diet. The approximated effect ratios for water use efficiency, energy use efficiency, pesticide use efficiency, and fertilizer use efficiency are presented in Table 2. Our analysis further showed that these differences resulted primarily from the inclusion of beef in the diet of the nonvegetarian. This finding is similar to those published by groups in Europe (4, 19), Japan (51), the United States (27, 52), and Australia (6, 53).

Can Mao, CL/R, 07/03/2010