This is not true. The book you cite, 'SuperFreakonomics,' by Steven Levitt and Stephen Dubner, apparently misquotes the original research on which they base their claim. Here's a quote from the book[1]:
"Even the 'locavore' movement, which encourages people to eat locally grown food, doesn't help in this regard. A recent study by two Carnegie Mellon researchers, Christopher Weber and H. Scott Matthews, found that buying locally produced food actually increases greenhouse-gas emissions."
But compare that to how one of the two authors of the original study, Christoph Weber, actually summarizes their findings[2]:
"The point of the paper was to say that yes, you can lower your footprint by eating local foods, but you can do more on average by eating differently. It’s not that eating local is a crock."
In that light, it seems as if Levitt and Dubner either misunderstood the paper by Weber and Matthews or preferred to portrait it in a light that helps make their own book look profound and surprising.
"Even the 'locavore' movement, which encourages people to eat locally grown food, doesn't help in this regard. A recent study by two Carnegie Mellon researchers, Christopher Weber and H. Scott Matthews, found that buying locally produced food actually increases greenhouse-gas emissions."
But compare that to how one of the two authors of the original study, Christoph Weber, actually summarizes their findings[2]:
"The point of the paper was to say that yes, you can lower your footprint by eating local foods, but you can do more on average by eating differently. It’s not that eating local is a crock."
In that light, it seems as if Levitt and Dubner either misunderstood the paper by Weber and Matthews or preferred to portrait it in a light that helps make their own book look profound and surprising.
[1] http://abcnews.go.com/2020/Books/superfreakonomics-read-exce...
[2] http://pubs.acs.org/doi/full/10.1021/es900427m?cookieSet=1