Which is better for the environment?  Shopping online or going to the store?

This is one of those “it all depends” questions.  At one extreme, walking to a local store to buy a locally produced, minimally packaged product would easily win over ordering a similar item from Amazon.  At the other extreme, if you’d be driving 20 miles to the mall to buy an item made far away, Amazon wins.

There are too many variables in the equation for a single answer: energy to transport, different transportation methods and circumstances, amount and type of packaging and its disposal or recycling, the equality of the local product (if any) to the remotely produced one, the energy and environmental cost of a storefront operation, and how much weight you give to environmental cleanliness compared to energy consumption.

For energy and greenhouse gas concerns, all else being equal, any product that you do not have to transport by car generally wins.  Commercial shipping to your door is energy efficient because, basically, your item is ride-sharing with many other items.  The same applies to products shipped to the store for pickup; however, making a special trip to drive it home from the store is like hiring it a limousine for the last leg, which spoils the advantage. 

Walking it, biking it, or carrying it home from the store by public transportation probably shifts the advantage to the store purchase.  If those modes of transportation aren’t possible and you must drive, unless you can pick it up on the way to or from somewhere, direct shipping to your home beats driving to the storefront.

The Center for Energy and Climate Solutions claims "Shipping 10 pounds of packages by overnight air -- the most energy-intensive delivery mode -- uses 40 percent less fuel than driving roundtrip to the mall.  Ground shipping by truck uses just one-tenth of the energy of driving yourself."  In addition, a store has lots of environmental overhead: extra lighting and heating, staff who commute, a large, rainwater-impervious parking lot surface, more sewage and water required…

For packaging concerns (pollution and energy of manufacturing, solid waste stream, recycling), buying the item from the store wins.  The product probably has identical factory packaging in both cases, but Amazon also has to stick it in a shipping box, probably with some sort of padding.  Mitigating the Amazon disadvantage are circumstances like shipping multiple purchases in one box, the use of environmentally sound packaging, and your ability to recycle or re-use the packaging.

My take on it is: order online if possible, order multiple products in a single shipment if possible, and re-use or recycle the shipping materials.  For immediacy, buy in a store but don’t make a special trip for one item.  Buy locally produced versions of the product if available, and buy in quantity if the item is consumable and doesn’t go bad.  Then bungee that giant 24-roll pack of locally-made toilet paper (and the dozen or so other locally-produced non-perishable items you bought on the same trip) onto the back of your bike and, wearing Polartec underwear made from recycled bottles and a hemp jump suit, peddle that sucker home.  Do NOT go back for the bottle of milk you forgot!  Or at least until I have a chance to research the living daylights out of the cardboard vs. glass issue, BGH, fat content, grass vs. corn feed, and organically-fed cows.

Treehugger.com has a more detailed analysis.