The author of today’s post, Sheryl Canter, is an Online Writer and Editorial Manager for the Climate 411 blog.at Environmental Defense.

When it’s apple season here in New York and the green markets are overflowing, for a store to ship in apples from Washington State or New Zealand burns fuel for no good reason. Local food is fresher, tastes better, and supports the community. And locally produced food often results in lower greenhouse gas emissions - but not always. The greenhouse gas calculation is complicated, and you can’t assume that if a crop is produced locally, greenhouse gas emissions are lower.

For starters, the term "food mile" is itself problematic. A mile travelled by a large truck full of groceries is not the same as a mile travelled by a mini-van carrying a crate of carrots. A report published by DEFRA [PDF], Britain’s environment and farming ministry, says it’s more useful to think in terms of "food-vehicle miles" (the miles travelled by vehicles carrying food) and food-tonne miles (which considers the tonnage being carried).

The DEFRA report contains several counterintuitive findings:

• Trucking in tomatoes from Spain during the winter produces less greenhouse gas emissions than growing them in heated greenhouses in Britain.
• A shift towards local food systems might actually increase the number of food-vehicle miles travelled. This is because supermarket-based food systems have central distribution depots, short supply chains, and big full trucks. In local food systems, food is distributed in a larger number of smaller, less efficiently packed vehicles.

But the DEFRA report is not the last word on the subject. The Leopold Center for Sustainable Agriculture found different results in its 2001 study "Food, Fuel and Freeways." They reported that conventional food systems used 4 to 17 times more fuel and emitted 5 to 17 times more CO2 than local and regional food systems, depending on the system and truck type.

A Lincoln University study [PDF] included elements they called "factor inputs and externalities" in analyzing the impact of food miles - for example, the amount of water and fertilizer used, harvesting and storage techniques, means of transport, and dozens of other aspects of cultivation. They found that lamb raised on New Zealand’s lush pastures and shipped 11,000 miles by boat to Britain produced 1,520 pounds of CO2 per ton, while British lamb produced 6,280 pounds. The reason? British pastures provide poorer grazing, forcing farmers to use feed. They found similar results for dairy products and fruit.

There’s a push for "food miles" labeling in both the U.S. and Europe. North Carolina State University’s Center for Environmental Farming Systems is working with FoodLogiQ to develop a pilot program in North Carolina with an eye towards national implementation. Local food is fresher and supports the community, so a locale label can tell you that much. But "local" doesn’t necessarily mean lower greenhouse gas emissions. That depends largely on how the food is produced and transported. Just knowing where the food was produced doesn’t tell you that.

Read more posts on Environmental Defense’s Climate 411 blog.

The author of today’s post, Sheryl Canter, is an Online Writer and Editorial Manager at Environmental Defense.

Total greenhouse gas emissions from cars and trucks is a function of three factors: amount of driving, fuel economy, and carbon emissions per gallon of fuel (the "three-legged stool [PDF]"). The news media tend to focus on the latter two factors, but how much people drive has a huge impact.

A new report published by the Urban Land Institute says that greenhouse gas emissions cannot be reduced sufficiently by making vehicles more efficient, because growth in driving cancels out improved fuel economy. People also must drive less. And the report’s solution is not just better public transportation.

The way to reduce driving sufficiently, the authors say, is to shift development patterns to favor compact, mixed-land-use neighborhoods where you can walk to school and the grocery store. If you live in a car-dependent area, moving to a walkable area will do more to fight global warming than buying a fuel-efficient hybrid car.

This idea is already being put into action in some areas. New York City is expecting one million more people by the year 2030, and is using rezoning to direct development towards areas with strong transit access.

Environmental Defense helped California’s San Joaquin Valley, which is notorious for bad air quality, implement a similar strategy. The Air Pollution Control Board adopted an incentive program [PDF] that gives developers two choices: reduce the environmental impact by creating sidewalks, bike paths, and nearby schools and commercial districts, or pay a fee for any excess pollution.

Living in a walkable neighborhood has other advantages. Recently released figures from the New York City Department of Health show that New Yorkers tend to live longer than most people in the country — an odd finding considering the lack of fresh air and other hazards. The city’s Commissioner of Public Health thinks it’s because New York is a walking city.

Many a book has seeded, incubated and hatched great change in the world. In fact, Rachel Carson's Silent Spring, which exposed the hazards of pesticides, gave birth to the modern environmental era. From Thoreau's Walden, that staple of English classes, to Dr. Seuss's The Lorax, which inspired many of us as children, the environmental movement has gathered momentum from a slew of informative, visionary and literary works.

Our staff compiled a list of favorites, so this summer, check these out for your next good read.

Here's the list. Vote for the most influential, and tell us what's missing.

Nonfiction

Cadillac Desert: The American West and Its Disappearing Water
Marc Reisner

Collapse
Jared Diamond

The Creation: An Appeal to Save Life on Earth
E.O. Wilson

Desert Solitaire
Edward Abbey

Earth in the Balance: Ecology and the Human Spirit
Al Gore

The Omnivore's Dilemma
Michael Pollan

A Sand County Almanac
Aldo Leopold

Silent Spring
Rachel Carson

Song for a Blue Ocean
Carl Safina

Walden
Henry David Thoreau

Wilderness and the American Mind
Roderick Nash

Fiction

Animal Dreams
Barbara Kingsolver

The Lorax
Dr. Seuss

Again, get more details on the books, vote for your favorite and tell us what's missing.