The Environmental Impact of Online Shopping: Nitty-gritty

September/October 2009

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Q: Is online shopping likely to save on carbon emissions or not? How do the carbon emissions compare between me driving a 15-mile round-trip to the bookstore versus the carbon emissions for Amazon to ship the book through their warehouse and UPS to me, including the extra packaging?

Asked by Dan Scales, MS ’86, PhD ’96, Mountain View, Calif.

Background information: Book e-tailers

While reading books might not be the national pastime, it’s certainly a popular one. A recent survey estimated that 60 percent of American adults bought one or more books in the past year. Thirty-eight percent visited a traditional brick-and-mortar bookstore, 14 percent visited only online booksellers, and 24 percent bought books from both. (Others purchased their books from discount stores, book clubs and other outlets.)

Online merchants represent a rapidly growing portion of the American book trade. From 1998 to 2003, online book sales increased from approximately $800 million to $2.5 billion. In the traditional bookstore world, just 27 percent of retail book sales are generated by the three largest chains: Barnes & Noble, Borders and Books-A-Million. In contrast, the monolithic—and expanding— dominates the online market.

In order to quantify the carbon emissions produced by purchasing a book online versus purchasing one from a physical retail store, a detailed look at each product pathway is necessary.

Life-cycle analysis: Book e-tail vs. retail

Both online and brick-and-mortar booksellers sell the same product: the written word, printed on sheets of paper (perhaps recycled, perhaps not), and bound with varying thicknesses of cardboard. Since they share the same basic product, emissions produced by book e-tailers and retailers will not differ until books leave the manufacturing stage and are shipped to either kind of merchant.

e-tail pathway
Figure 1. Traditional Retail Product Pathway.

Traditional bookstore

First, let’s assume each bookseller begins with the exact same book: hence, the materials used in printing and the energy consumed by the printing process are equivalent. The retail product pathway begins when the book ships from its printer to a publisher’s warehouse, usually via heavy-duty truck, and typically packaged in bulk with hundreds or thousands of its literary brothers. Until a bookstore places an order, those books linger in a climate-controlled storage facility. On its way to stores, a book will pass through at least one—if not two or three—additional intermediate warehouse or distribution facilities.

The last step in the retail product pathway involves a new character: the customer herself. According to the National Retail Federation, most shopping trips are conducted by an individual driver traveling at least seven miles roundtrip—and likely as many as 30—to purchase a single item.

e-tail pathway2
Figure 2. E-tail Product Pathway.

E-tail bookstore

At first, the product pathway for a book bound for the online marketplace is the same as that purchased from a retail store. Following printing, books are packaged in bulk, shipped via heavy-duty truck, wait at the merchant’s warehouse and, once ordered, set off on another journey. Key differences emerge at this stage, however: the book is delivered to a sorting facility, repackaged for individual shipping and transported to the delivery agent’s distribution warehouse by airplane or truck, depending on the delivery time selected by the individual consumer. Lastly, the book is delivered to a specific home address, typically by a light delivery truck, which may or may not be equipped with energy-efficiency technology.

Retail and e-tail comparison

The initial stages of e-tail and retail product pathways are remarkably similar. Key differences between the two include “last-mile energy,” transportation, energy use and packaging materials (Figure 3).

Pathway Stage or Component Description Affected Pathway
Heavy-duty truck High-capacity (25 tons) vehicles typically achieving 8.5 miles per gallon (mpg) Retail and E-tail
Light-duty truck Moderate-capacity (10 tons) vehicles achieving, on average, 15 mpg E-tail only
Last-mile energy Energy consumed by transportation of product to final destination E-tail: from local distribution facility to customer home

Retail: from retail store to customer home
Packaging Packing materials: assumed thin-film plastics and corrugated cardboard Primarily E-tail
Building energy use Energy required to light, heat and cool warehouse / retail facilities: approximately 13.5 g CO2 per shipment Primarily Retail
Figure 3. General definitions and quantifications of key retail and e-tail product pathway stages and components.

The key product pathway stages or elements (Figure 4) for the retail and e-tail comparison are consumer driving, last-mile delivery, packaging and building energy use. By far the most significant of these parameters are consumer driving behavior, including distance traveled to purchase a book, and the fuel economy of the consumer’s vehicle.

e-tail emissionsFigure 4. The relative importance of CO2 emission increases (right) and decreases (left) associated with retail and e-tail system stages or components.

e-tail emissions2Figure 5. CO2 emissions associated with retail and e-commerce product pathway stages.

The bottom line? Unless you’re walking or biking to the bookstore, buying a book online results in lower carbon emissions than purchasing it from a traditional bookstore. Light-duty delivery vehicles operated by companies like UPS and FedEx travel well-designed routes that serve multiple consumers in a minimum of trips, achieving fuel economy higher than that of a typical individual consumer driving alone to make the same purchase.

Packaging—which has its own carbon footprint—provides an important footnote to e-tail’s victory, however. Some online sellers do offer bulk or environmentally friendly packing material options. offers “Ecosend,” a service that offsets the carbon emissions caused by shipping with investments in renewable energy projects in Native American communities. Amazon has partnered with CarbonCart to buy credits to offset the CO2 produced by each item shipped. An internet search will produce oodles of similar organizations promising various carbon offset schemes, but the simplest solution may be to reuse the boxes, or “freecycle” them to others in your community if you have too many.

Other ways to lower carbon emissions from book purchases

Shipping companies including DHL, FedEx and UPS, and the U.S. Postal Service, are addressing the climate impact of their delivery fleets. UPS in particular is marketing itself as a greener shipper, with a substantial fleet of alternative fuel delivery vehicles, including compressed natural gas, hybrid electric, all-electric, fuel cell and hydraulic drive train trucks. But there are ways to avoid the trucks altogether.

Bookstores typically return, recycle or simply discard unsold books, though some might be re-sold to a discount store. All of these afterlife options produce additional carbon emissions, not fewer. Acquiring books from libraries, used bookstores or swap meets may cut into publishing profits, but it also cuts out the material waste of printing new books. You’re still responsible for those “last mile” emissions though, so make that library trip by bike.


1. “Book Retailing,” Mintel International Group Ltd, June 2004

2. “C saved shopping online” Oak Ridge National Laboratory, December 2007

3. “Online Books,” Mintel International Group Ltd, July 2004

4. “Trends in Online Shopping,” Nielsen Media Research, February 2008

5. “UPS takes the lead on hydraulic hybrids,” Businessweek, November 2008

6. All figures except Figure 3 from: “Life Cycle Comparison of Traditional Retail and E-commerce Logistics for Electronic Products: A Case Study of,” Carnegie Mellon Green Design Institute, December 2008.

Anna Argyridou received her MS in environmental engineering and science in June 2009.

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